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1
Local, Andrea. "Cloning of Carbonic Anhydrase from Cotton (Gossypium hirsutum L.)." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc279044/.
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Carbonic anhydrase is a ubiquitous zinc-metalloenzyme that catalyzes the interconversion of carbon dioxide and carbonate and has been found to play a wide range of roles in animals, plants and bacteria. Cotton genomic and cDNA libraries were screened for the plastidial isoform of carbonic anhydrase. The nucleotide sequences of two 1.2 Kb partial cDNA clones were determined. These clones exhibit high homology to carbonic anhydrases from other dicot plants and possess all the expected peptide motifs. For example, serine and threonine rich chloroplastic targeting peptide and conserved zinc binding residues are both present. These clones were utilized to isolate two carbonic anhydrase genes that were shown to encode different isoforms by PCR and RFLP analysis.
2
Baloch, Gul Muhammad M. "Cell-bound phosphatase activity in cotton (Gossypium hirsutum L.) roots." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5128/.
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A study was made of phosphorus nutrition in cotton cultivars derived from Pakistan with particular reference to phosphatase activity. Cultivars used were Qalandri, Rehmani, Reshami and TH-3/83; Qalandri was used for most of the phosphatase characteristic studies, since this cultivar exhibited the highest germination percentage and seedling establishment. Investigations of soil parameters from cotton growing region of Pakistan were also carried out. Soil pH was above 8.0 in all sites studied. Soil organic component levels were very variable between sites and within sites at different depths. Soil potassium was found to be at levels regarded as being sufficient for sustaining plant growth at all sites. However, levels of combined nitrogen and inorganic phosphate were in the range of values which could be regarded as being limiting to plant growth. The importance of phosphatase in the mobilization of organic phosphorus was therefore apparent. Phosphomonoesterase (PMEase) activity, assayed using two substrates p- nitrophenyl phosphate (pNPP) and 4-methylumbelliferyl phosphate (4-MUP), was investigated and was found associated with roots of hydroponically-grown seedlings. Staining studies indicated that the enzymes were present in the cell wall. Phosphodiesterase activity was also detected in roots, using bis-pNPP as the substrate. PMEase activity was found to have its greatest activity at pH values between 4.0 and 6.0 for all cultivars. In cv Qalandri the optimum pH for PMEase activity was 5 .5 and the optimum temperature was 55 C when assays were incubated over a 1h period using pNPP or 4-MUP as the substrate. Levels of activity were higher using pNPP than with 4-MUP, but an absolute direct comparison could not be made since the concentrations of the individual substrates used were different. Plants grown in phosphate-limitation conditions showed enhanced PMEase activity. Enhancement of PMEase activity was associated with the levels of phosphate in the plant growth nutrient solution rather than with those in the plant itself This activity was highest in 19-day old seedlings, under the conditions of growth employed here. A comparison between cultivars showed some differences in the level of PMEase activity and in the specific pH optimum for enzyme activity. Limitation of combined nitrogen to seedling also resulted m enhanced PMEase even when plants were under phosphate-sufficient conditions. A similar effect of potassium-limitation was also found and this was associated with reduced uptake of phosphate into the seedlings. No effect of magnesium-limitation on PMEase activity was found. A comparison was also made with other plants; cotton. Primula farinosa, rice, wheat and algae. All had associated phosphatase activity, with cotton showing significantly higher root acid phosphatase activity than the other higher plant species. Acidic phosphatase activity was found in the alga Drapamaldia whilst Stigeoclonium had alkaline phosphatase.
3
Saka, Kamel. "REGENERATION OF COTTON (GOSSYPIUM HIRSUTUM L.) CALLUS PROTOPLASTS TO MACROCALLI." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275376.
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Justi, Maria Marta [UNESP]. "Cloreto de Mepiquat em cultivares de algodoeiro (Gossypium hirsutum L.)." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/105176.
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Com o objetivo de avaliar o efeito de doses de cloreto de mepiquat em cultivares de algodão herbáceo, foi conduzido um experimento no ano agrícola de 2002/2003, na Fazenda de Ensino e Pesquisa da FEIS/UNESP, localizada no município de Selvíria (MS). O delineamento experimental utilizado foi o de blocos ao acaso, com parcelas subdivididas, e quatro repetições. Nas parcelas foram estudados quatro cultivares de algodão (Coodetec 401, IAC 24, DeltaOpal e Deltapine Acala 90) e nas subparcelas, três doses de cloreto de mepiquat (0,0; 50,0 e 100,0 g i.a.ha-1). As parcelas experimentais constituíram-se de seis linhas com 10 m de comprimento e 0,90 m de espaçamento entrelinhas, sendo consideradas úteis as quatro linhas centrais. Foram determinados, em dez plantas de cada parcela, a altura das plantas e o diâmetro do caule. O número de nós no caule, número de ramos e de capulhos por planta foi obtido em cinco plantas amostradas de cada parcela. A produção de algodão em caroço foi determinada através da colheita dos capulhos em quatro metros de cada uma das duas linhas centrais. Amostras de 20 capulhos de cada parcela foram utilizadas para a obtenção da massa média de um capulho, massa de 100 sementes, porcentagem de fibra e características tecnológicas da fibra. A análise de crescimento foi feita determinando-se, a cada 14 dias, a área foliar e a massa seca acumulada nos diferentes órgãos da planta. A partir desses dados foram calculados a área foliar total, razão de área foliar, área foliar específica, razão de massa de folhas, taxa de crescimento relativo e taxa assimilatória líquida. Considerando-se 100% a massa seca total, determinou-se a distribuição em porcentagem da massa seca entre as diferentes estruturas da planta...
The experiment was conducted with the objective of evaluating the effect of doses of mepiquat chloride in cotton cultivars in the agricultural year of 2002/2003, at Teaching and Research Farm of FEIS/UNESP, located in Selvíria, MS, Brazil. The experimental design was complete blocks in split-plot arrangement and four replications. In the plots four cotton cultivars (Coodetec 401, IAC 24, DeltaOpal and Deltapine Acala 90) were studied and in the subplots, three doses of mepiquat chloride (0,0; 50,0 and 100,0 g i.a.ha-1). The experimental plots had six rows with 10 m of length and 0,90 m between rows, being considered useful the central four rows. The height of the plants and the diameter of the stem were measured in ten plants in each plot. The number of nodes in the stem, number of branches and of fruits per plant were obtained in five plants collected from each plot. The cotton yield was determined through the harvested fruits of the two central rows. Samples of 20 fruits of each plot were used to obtain the average mass of one fruit, mass of 100 seeds, fiber percentage and technological characteristics of the fiber. The growth analysis was performed by determining, every 14 days, the leaf area and the dry mass accumulated in the different organs of the plant. From those data, total leaf area, leaf area ratio, specific leaf area, ratio of leaf mass, relative growth rate and net assimilation rate, were calculated. Considering the total dry mass as 100%, the distribution, in percentage, of the dry mass among the different structures of the plant was determined. The obtained results allowed to conclude that 50,0 g i.a.ha-1 of mepiquat chloride caused minor height of the plants in the Coodetec 401, DeltaOpal and Deltapine Acala 90 cultivars while, for 24 IAC the dose of 100,0 g i.a.ha-1 was the best... (Complete abstract, click eletronic address below)
5
McHugh, John. "Molecular and biochemical characterization of phospholipase D in cotton (Gossypium hirsutum L) seedlings." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4732/.
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N-Acylethanolamines (NAEs) are enriched in seed-derived tissues and are believed to be formed from the membrane phospholipid, N-acylphosphatidylethanolamine (NAPE) via the action of phospholipase D (PLD). In an effort to identify a functional NAPE-PLD in cotton seeds and seedlings, we have screened a cotton seedling cDNA (cotyledon mRNA from 48 h dark grown seedlings) library with a 1.2 kb tobacco partial cDNA fragment encoding the middle third of a putative PLDβ/γ (genbank accession, AF195614) isoform. Six plaques were isolated from the Uni-ZAP lambda library, excised as pBluescript SK(-) phagemids and subjected to nucleotide sequence analysis. Alignment of derived sequences with Arabidopsis PLD family members indicated that the cDNAs represent six different PLD gene products -three putative PLD β isoforms and three putative PLD δ isoforms. The PLD β isoforms, designated Ghpldβ1a, GHpldβ1b and a truncated Ghpldβ1b isoform. Both the full-length PLD β proteins contained characteristic HKxxxxD catalytic domains, a PC-binding domain, a PIP2-binding domain and a C2 domain. In addition both cotton PLD β isoforms had a N-terminal "SPQY" rich domain which appeared to be unique to these PLDs. The three PLD δ isoforms, designated Ghpldδ1a, Ghpldδ1b and Ghpldδ1b-2 encode full-length PLDδ proteins, and like the above PLDs, contained the characteristic catalytic and regulatory domains. The expression of Ghpldδ1b showed hydrolytic and transphosphatidylation activity toward radiolabelled phosphatidylcholine (PC) but it appears Ghpldδ1b does not utilize NAPE as a substrate to produce NAEs nor does it seem to be suppressed by NAEs.
6
Justi, Maria Marta. "Cloreto de Mepiquat em cultivares de algodoeiro (Gossypium hirsutum L.) /." Jaboticabal : [s.n.], 2005. http://hdl.handle.net/11449/105176.
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Orientador: Izabel Cristina LeiteBanca: Luiz Henrique Carvalho
Banca: Paulo Roberto de Camargo e Castro
Banca: Antonio César Bolonhezi
Banca: Manoel Luiz Ferreira Athayde
Resumo: Com o objetivo de avaliar o efeito de doses de cloreto de mepiquat em cultivares de algodão herbáceo, foi conduzido um experimento no ano agrícola de 2002/2003, na Fazenda de Ensino e Pesquisa da FEIS/UNESP, localizada no município de Selvíria (MS). O delineamento experimental utilizado foi o de blocos ao acaso, com parcelas subdivididas, e quatro repetições. Nas parcelas foram estudados quatro cultivares de algodão (Coodetec 401, IAC 24, DeltaOpal e Deltapine Acala 90) e nas subparcelas, três doses de cloreto de mepiquat (0,0; 50,0 e 100,0 g i.a.ha-1). As parcelas experimentais constituíram-se de seis linhas com 10 m de comprimento e 0,90 m de espaçamento entrelinhas, sendo consideradas úteis as quatro linhas centrais. Foram determinados, em dez plantas de cada parcela, a altura das plantas e o diâmetro do caule. O número de nós no caule, número de ramos e de capulhos por planta foi obtido em cinco plantas amostradas de cada parcela. A produção de algodão em caroço foi determinada através da colheita dos capulhos em quatro metros de cada uma das duas linhas centrais. Amostras de 20 capulhos de cada parcela foram utilizadas para a obtenção da massa média de um capulho, massa de 100 sementes, porcentagem de fibra e características tecnológicas da fibra. A análise de crescimento foi feita determinando-se, a cada 14 dias, a área foliar e a massa seca acumulada nos diferentes órgãos da planta. A partir desses dados foram calculados a área foliar total, razão de área foliar, área foliar específica, razão de massa de folhas, taxa de crescimento relativo e taxa assimilatória líquida. Considerando-se 100% a massa seca total, determinou-se a distribuição em porcentagem da massa seca entre as diferentes estruturas da planta... (Resumo completo, clicar no acesso eletrônico abaixo)
Abstract: The experiment was conducted with the objective of evaluating the effect of doses of mepiquat chloride in cotton cultivars in the agricultural year of 2002/2003, at Teaching and Research Farm of FEIS/UNESP, located in Selvíria, MS, Brazil. The experimental design was complete blocks in split-plot arrangement and four replications. In the plots four cotton cultivars (Coodetec 401, IAC 24, DeltaOpal and Deltapine Acala 90) were studied and in the subplots, three doses of mepiquat chloride (0,0; 50,0 and 100,0 g i.a.ha-1). The experimental plots had six rows with 10 m of length and 0,90 m between rows, being considered useful the central four rows. The height of the plants and the diameter of the stem were measured in ten plants in each plot. The number of nodes in the stem, number of branches and of fruits per plant were obtained in five plants collected from each plot. The cotton yield was determined through the harvested fruits of the two central rows. Samples of 20 fruits of each plot were used to obtain the average mass of one fruit, mass of 100 seeds, fiber percentage and technological characteristics of the fiber. The growth analysis was performed by determining, every 14 days, the leaf area and the dry mass accumulated in the different organs of the plant. From those data, total leaf area, leaf area ratio, specific leaf area, ratio of leaf mass, relative growth rate and net assimilation rate, were calculated. Considering the total dry mass as 100%, the distribution, in percentage, of the dry mass among the different structures of the plant was determined. The obtained results allowed to conclude that 50,0 g i.a.ha-1 of mepiquat chloride caused minor height of the plants in the Coodetec 401, DeltaOpal and Deltapine Acala 90 cultivars while, for 24 IAC the dose of 100,0 g i.a.ha-1 was the best... (Complete abstract, click eletronic address below)
Doutor
7
Lehle, F. R., and A. M. Zegeer. "Effect of NaCl on the Growth of Germinating Upland Cotton (Gossypium hirsutum L.) Seeds." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/208316.
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Responses to environmental stresses such as excess salinity are difficult to understand if not studied under defined conditions. The objective of this study was to determine if cottonseed radicle and cotyledon growth during germination was affected by exogenous NaCl. Cottonseeds were imbibed in moistened paper toweling for 24 h at 32°C before transfer to an agar media containing selected concentrations of NaCl for an additional 24 h. Radicle linear growth extension was stimulated at low NaC1 concentrations (80 mM), but increasingly inhibited as NaCl concentrations increased from 160 to 400 mM. Radicle and cotyledon fresh weights were increasingly inhibited by NaCl concentrations between 0 and 400 mM. NaCl inhibition of radicle fresh weights was more pronounced than that of cotyledons. We conclude that the inhibitory effects of NaCl can be quantified as reductions in cottonseed radicle and cotyledon growth.
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Vasconcelos, Ubieli Alves Araújo. "Análise dialética em algodoeiro (Gossypium hirsutum L.) para tolerância à seca." Universidade Estadual da Paraíba, 2016. http://tede.bc.uepb.edu.br/tede/jspui/handle/tede/2333.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Cotton is a crop of large economic value at worldwide. The Brazilian production is around 1.5 million tons, coming mainly from the Mid West, Southeast and Northeast region, specially Cerrado areas. Despite to importance of crop to Brazil, there is a broad demand to investment in breeding area focusing on selection of promising genotypes as to yield and regional adaptation. In order to attend this demand, breeding programs have focused on generation of different lines by hybridization, using robust genitors, aiming broaden the genetic background of the lines and to favor the selection procedures. In this study we used 20 cotton lines, obtained through diallel crosses with parents of Moco and herbaceous types, aiming to estimate the GCC and SCC in materials tolerant to drought, based on agronomic traits. The study was carried out in semiarid environment, at Barbalha Station, CE, in dry season, using water supplementation. After the appearance of the first buds, plants were subjected to 23 days of water suppression, and re-established watering thereafter. The experimental design was randomized blocks, with 20 treatments and factorial scheme (20 x 2), and three replications. The variables evaluated were: plant height, Productivity, fiber percentage, Boll weight, Rising of first flower and Rising of first boll. Additionally, total chlorophyll content in leaves was determined. The statistical analysis wasperformed by GENE program. Analyses of combinatorial capacities were performed according to the method adapted by Griffing (1956), which estimates the effects of GCC of each parent and the effects of SCC. There was wide variation between the parents for the analyzed variables. The follow parents showed best estimates of GCA, and therefore, have more favorable alleles, based on traits studied: BRS 286, CNPA 5M and CNPA 7MH. To SCC, the hybrids BRS 286 X CNPA 5M, BRS RUBI X CNPA 5M and BRS 286 X BRS Serido demonstrated complementarity Plant hight and porductivity. The estimates of GCC and SCC presented in this paper provided valuable inputs to cotton improvement, as to both parents and hybrid selections.
O algodão é uma cultura de grande importância econômica mundialmente. No Brasil a produção encontra-se na faixa de 1,5 milhões de toneladas, oriundas principalmente das regiões Centro - Oeste, Sudeste e Nordeste, com maior área situada nos Cerrados. Apesar do crescimento da cultura em nível nacional, há necessidade de investimento na área de melhoramento genético com fins de selecionar genótipos promissores para produção e adaptação regional. Para tanto, os programas de melhoramento têm focalizado na geração de linhagens divergentes, por meio de hibridações com progenitores robustos, de modo a ampliar a base genética das linhagens e favorecer os procedimentos de seleção. Nesse trabalho utilizou-se uma população composta de 20 híbridos de algodão, obtida via cruzamentos dialelicos com genitores dos tipos arbóreo e herbáceo, objetivando estimar as CGC e CEC dos materiais tolerantes a seca, focalizando em caracteres agronômicos. O trabalho foi conduzido em ambiente semiárido, em Barbalha, CE, em regime de sequeiro com complementação hídrica.Após o surgimento dos primeiros botões florais, as plantas foram submetidas a 23 dias de supressão hídrica, sendo restabelecidas as regas após esse período. O delineamento experimental adotado foi de blocos ao acaso, com 20 tratamentos, com esquema fatorial 20 x 2, e três repetições. As variáveis avaliadas foram: Altura de planta, Produtividade, Percentagem de fibras, Peso de um capulho, Surgimento da primeira flor e Surgimento da primeira maçã. Adicionalmente, determinou-se o teor de Clorofila total nas folhas. As analises estatísticas foram realizadas pelo programa GENES. As análises das capacidades combinatórias foram realizadas de acordo com o modelo adaptado por Griffing (1956), que estima os efeitos da capacidade geral de combinação CGC de cada parental e os efeitos da capacidade específica de combinação CEC. Verificou-se ampla variabilidade entre os genitores para as variáveis analisadas. Os genitores que apresentaram as melhores estimativas de CGC e com maior número de alelos favoraveis para as principais características estudadas foram BRS 286, CNPA 5M e CNPA 7MH, enquanto que para CEC, os híbridos BRS 286 X CNPA 5M, BRS RUBI X CNPA 5M e BRS 286 X BRS SERIDO destacaram-se por demonstrar melhores estimativas de CEC e complementaridade para ALT e PROD em condições de estresse hídrico. As estimativas de CGC e CEC ofereceram contribuições valiosas no processo de seleção no melhoramento genético, tanto de genitores como de combinações hibridas.
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Askew, Matthew Carter. "Rapeseed (Brassica napus L.) Termination and Integration of Halauxifen into Virginia Cotton (Gossypium hirsutum L.) Production." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/86786.
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Cover crops have become an important part of cropping systems in the United States, especially in the Mid-Atlantic region. Rapeseed is a popular choice due to its deep growing taproot which creates soil macropores and increases water infiltration. If not properly terminated rapeseed can become problematic due to its pod-shattering tendency and its difficulty to terminate with herbicides once it enters reproductive growth. Results indicate termination of rapeseed is most effective when the cover crop is small. Combinations that successfully terminated rapeseed include glyphosate plus 2,4-D and paraquat plus 2,4-D. Halauxifen-methyl is a new Group 4 herbicide marketed for preplant burndown horseweed (Conyza canadensis L.) control. Previous research indicates that halauxifen effectively controls glyphosate-resistant horseweed. However, little is known about control of other common winter annual weeds by halauxifen. Results indicate halauxifen has a narrow spectrum of control providing adequate control (>80%) of horseweed, henbit (Lamium amplexicaule L.), and purple deadnettle (Lamium purpureum L.), while failing to control cutleaf evening-primrose (Oenothera laciniata Hill), curly dock (Rumex crispus L.), purple cudweed (Gamochaeta purpurea L. Cabrera), common chickweed (Stellaria media L.), and mousear chickweed (Cerastium L.). Little is known of cotton (Gossypium hirsutum L.) tolerance to halauxifen applied preplant burndown. Results indicate cotton is more tolerant to halauxifen than 2,4-D or dicamba when the interval between preplant application and cotton planting is less than 30 days.Master of Science in Life Sciences
Cover crops are an important part of cropping systems in the United States, especially in the Mid-Atlantic region. Producers utilize cover crops to aid in weed suppression, reduce soil erosion, as well as to increase soil health. Cereals, legumes, and Brassicaceae species are popular cover crops planted either as monocultures or mixtures. Rapeseed can become problematic due to its difficulty to terminate once it enters reproductive stage, as well as its podshattering characteristic. Experiments were conducted to evaluate various herbicides and herbicide combinations for rapeseed termination two application timings. At three locations where rapeseed averaged 12 cm in height at early termination, and 52 cm in height at late termination, glyphosate + 2,4-D was most effective, controlling rapeseed (96%) 28 days after early termination (DAET). Paraquat + atrazine + atrazine (92%), glyphosate + saflufenacil (91%), glyphosate + dicamba (91%), and glyphosate (86%) all provided at least 80% control 28 DAET. Paraquat + 2,4-D (85%), glyphosate + 2,4-D (82%), and paraquat + atrazine + mesotrione (81%) were the only treatments to provide at least 80% control 28 days after late termination (DALT). At one location where rapeseed was much taller (41 cm early termination; 107 cm late termination), herbicides were much less effective, as no herbicide treatments provided greater than 80% control. Results indicated that rapeseed size at time of termination was more critical to successful termination than herbicide choice. Prior to the development of glyphosate-resistant horseweed, producers were able to control horseweed and other weeds with glyphosate applied preplant burndown. Producers now rely on auxin herbicides tank mixed with glyphosate and a residual herbicide to control horseweed and other winter weeds prior to cash crop planting. Experiments were conducted to evaluate halauxifen-methyl, a new Group 4 herbicide, for control of horseweed and other commonly encountered winter annual weeds. Halauxifen (89%) controlled small horseweed (<5 cm in height at time of application) similar to dicamba (91%), while providing better control of large horseweed (79%) (>15 cm in height at time of application) than either dicamba (77%) or 2,4-D evaluated (64%). Halauxifen provided adequate control (>80%) of henbit (Lamium amplexicaule L). and purple deadnettle (Lamium purpureum L.), while failing to effectively control of cutleaf evening-primrose (Oenothera laciniata Hill), curly dock (Rumex crispus L.), purple cudweed (Gamochaeta purpurea L. Cabrera), common chickweed (Stellaria media L. Vill.), and mousear chickweed (Cerastium L.). Results indicate that halauxifen has a narrow spectrum of control and should be tank mixed with 2,4-D or glyphosate in order to control weeds other than horseweed and henbit. Glyphosate plus dicamba or 2,4-D plus a residual herbicide is typically applied prior to cotton planting. Previous research has shown that as long as rainfall requirements and rotation intervals are met, no adverse effects on cotton is observed from 2,4-D or dicamba herbicides. Little is known of cotton tolerance to halauxifen applied preplant burndown. Experiments were conducted to determine if halauxifen applied sooner than the labeled 30-day rotation interval would injure cotton. Very little injury was observed from halauxifen (9%) applied at-planting, however dicamba (26%) and 2,4-D (21%) applied at the same timing did injure cotton. Auxin herbicides applied earlier in the season resulted in little injury (<2%). Early season injury was transient as cotton recovered later in the season and seedcotton yield was unaffected.
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Al-Bahrany, Abdulaziz Maatook 1960. "Physiological and biochemical responses of short staple cotton (Gossypium hirsutum L.) to salt stress." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184634.
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Three cotton (Gossypium hirsutum L.) germplasms (DP62, 84027, and 84033) were used to investigate the physiology of salt tolerance. Lines 84027 and 84033 were developed from the parental line DP62 and showed superior vigor under varying NaCl conditions (0.5 to 2.0 M) during germination and emergence. Proline levels increased in the leaves of all germplasms in response to increasing salinity. Varietal differences in proline levels did not reflect their variation in salt tolerance. Several physiological characteristics were also evaluated under non-saline condition in the greenhouse. There were no significant differences among germplasm sources for all parameters measured. However, salinity reduced transpiration rate, increased leaf diffusive resistance and leaf temperature for all lines. Ribosomal-RNA levels in all germplasms were evaluated after seeds were stressed for 24 hrs in various concentrations of NaCl and then germinated under normal conditions for 72 hrs. Ribosomal-RNA levels were inversely related to salt concentrations. Line 84033 followed by line 84027 had highest ribosomal-RNA content than the parental line DP62 when averaged over the four salt concentrations. Sodium content (ppm/g FW) and Cl⁻ content (ppm/g FW) were evaluated in microsomal and cell walls fractions as well as a cytoplasmic fraction which consisted of vacuoles, mitochondria, and plastids. The Cl⁻ ion exhibited a greater consistency in a concentration shift from one fraction to another as a function of time than did the Na⁺ ion. As a result, there may be a correlation between the drop in ribosomal-RNA and the amount of Cl⁻ in the microsomal fraction. Other parameters measured in the germinating seed were soluble protein (globulin), insoluble proteins (prolamin and glutelin) and fiber percentage. Variations within the germplasms were shown to exist. This study shows that even among lines that have been selected for salt tolerance from a single variety, the possibility exists that each of these lines may have a different mechanism to cope with salt stress.
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Lehle, F. R., and A. M. Zegeer. "Exogenous L- and D-Proline Does Not Reduce NaCl Inhibition of Radidle Growth of Germinating Cotton (Gossypium hirsutum L.) Seeds." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/208318.
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The adaptive significance of proline (Pm) accumulation in cotton seeds can be assessed by determining if NaCl tolerance is influenced by changes in the Pm level of the seed. The objective of this study was to determine if exogenous L-Pro and D-Pro reduce NaCl inhibition of radicle growth of germinating cotton seeds. Seeds were imbibed for 24 h at 32°C before transfer to agar medium containing either Pro, NaCl or mixtures of both. Results indicate that exogenous Pro increases the Pro contents of cotton seed radicles and cotyledons to a similar extent. Such increases are independent of whether L- or D-Pro is fed exogenously. Results also show that exogenous Pro does not significantly reduce NaCl inhibition of radicle growth in germinating cotton seeds. .
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COSTA, Deivid Almeida da. "Embriogênese somática em algodão (Gossypium hirsutum L. cv. BRS – 187 – 8H)." Universidade Federal Rural de Pernambuco, 2007. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6225.
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The somatic embryogenesis is a technique of plant tissue culture with several application potentials, as in the clonal propagation of plants, in the regeneration of transformed cells and in the basic studies of the molecular, biochemical and morphologic events that happen duringthe embryogenesis. In spite of the several works reporting somatic embryogenesis in cotton, several problems still persist in the regeneration through embryogenesis. The most of the works is with the line cocker, due to the fact of the cotton to be recalcitrant for the somatic embryogenesis. This way, the present study was conceived with the intention of analyzing the morphogenic response of the cotton to several growth regulators and stressful agents during the induction of embryogenic callus and somatic embryos, correlating the callus production with the antioxidant enzymes expression. For induction of the embryogenic callus, hypocotyl of germinated cotton (BRS – 187 – 8H) surface-sterilized seeds was used. The embriogenic callus induction medium (MICE) consisted of the MSB medium with different combinations and concentrations of 2,4-D, Kinetin, 2iP and Picloram. For conversion of embryogenic callus, it was used the embryo induction medium (MIE) that consistes of MSB medium and MSB supplemented with zeatin; L-glutamine, asparagine; espermine, espermidine or different concentrations of NH4NO3 and KNO3. The results show that among the MICE tested, the medium with 0,1 mg L-1 2,4-D and 0,3 mg L-1 Kinetin (MSB1 medium) and the MCIM medium showed the largest average in the production of embryogenic callus by explant. Explants in the MIE-1 presented the best proliferation of the embryogenic callus. However, the formation of globular and embryogenic structures was only visualized in the embryogenic callus formed in MSB1 medium, which were transferred for MSB medium and subcultivated in MIE-4 medium. It was concluded that different growth regulators can induce the formation of embryogenic callus in cotton cultivar BRS – 187 – 8H and the suppression of the growth regulators favors the appearance of globular and pre-embryogenic structures. In the experiments of the influence of the stress in cotton callus formation and the isozymic antioxidant system expression, it was used for induction of embryogenic callus, thecombination of MSB and MSB1 medium with two concentrations of FeEDTA: the concentration standard of the MS medium; and a concentration five times larger. It wasestablished three regimes of luminous intensity: darkness; 3,4 Klx and 6,0 Klx. Embryogenic callus were obtained on the MSB1 (3,4 Klx), MSB1 (6,0 Klx) and MSB1+FeEDTA (5X) medium. The electrophoretic system of the catalase and peroxidase showed variation in the intensity of the bands. The results show that the embryogenic callus formation dependent of the action of growth regulators and of the light presence, and the isozymic standards of catalase and peroxidase present similar pattern and they are related with the embryogenic aspect of the calluses.
A embriogênese somática é uma técnica de cultura de tecidos vegetais com diversos potenciais de aplicação, como na propagação clonal de plantas, na regeneração de células transformadas geneticamente e nos estudos básicos dos eventos moleculares e bioquímicos e morfológicos que ocorrem durante a embriogênese. Apesar dos diversos trabalhos relatando embriogênese somática em algodão, vários problemas ainda persistem na regeneração via embriogênese e a maioria dos trabalhos é com a linha cocker, devido a recalcitrância do algodão a embriogênese somática. Deste modo, o presente estudo foi concebido com o intuito de analisar a resposta morfogênica do algodão a vários reguladores de crescimento e agentes estressantes durante a indução de calos embriogênicos e embriões somáticos, correlacionando a calogênese com a expressão de isoformas do sistema antioxidativo. Para indução dos calos embriogênicos utilizou-se sementes desinfestadas da cultivar de algodão BRS – 187 – 8H. Os meios de indução de calos embriogênicos (MICE) utilizados consistiram no meio MSB acrescido de varias combinações e concentrações dos reguladores de crescimento 2,4-D; Cinetina, Picloram e 2-iP. Já para conversão dos calos embriogênicos em embriões, utilizouse o meio de indução de embiões (MIE) que consiste no meio MSB e MSB acrescido dezeatina, ou diferentes concentrações de NH4NO3 e KNO3, ou acrescido de L glutamina; asparagina; espermina; espermidina. Os dados obtidos mostram que entre os MICE testados, o meio contendo 0,1 mg L-1 de 2,4-D e 0,3 mg L-1 de cinetina (meio MSB1) e o meio MCIM mostraram as maiores médias na produção de calos embriogênicos por explante. Entre os MIE, o MIE-1 apresentou melhor proliferação dos calos embriogênicos. Contudo, a formação de estruturas globulares e embriogênicas só foi visualizada nos calos embriogênicos formados em meio MSB1 e transferidos para meio MSB e subcultivados em meio MIE-4. Concluiu-se então que diferentes reguladores podem induzir a formação de calos embriogênicos na cultivar BRS – 187 – 8H, e a supressão dos reguladores de crescimento favorece o surgimento de estruturas globulares e pré-embriogênicas. Nos experimentos da influência do estresse na calogênese e a expressão de isoenzimas do sistema antioxidativo, utilizou-se para a induçãode calos embriogênicos a combinação do meio MSB e MSB1 com duas concentrações de FeEDTA: a concentração padrão do meio MS; e uma concentração cinco vezes maior. E foiestabelecido três regimes de intensidade luminosa: escuro; 3,4 Klx e 6,0 Klx. Calos embriogênicos foram obtidos nos meios MSB1(3,4 Klx), MSB1(6,0 Klx) e MSB1+FeEDTA(5X). Analises de eletroforese de isoenzimas da catalase e peroxidase mostraram variação na intensidade das bandas. Os resultados obtidos permitiram concluir que formação de calos embriogênicos é dependente da ação de reguladores de crescimento e da presença de luz, e que as isoformas de catalase e peroxidase apresentam padrão similar e estão relacionadas com o aspecto embriogênico dos calos.
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Hoang, Chau V. "Plastidial carbonic anhydrase in cotton (Gossypium hirsutum L.): characterization, expression, and role in lipid biosynthesis." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc2893/.
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Recently, plastidial carbonic anhydrase (CA, EC 4.2.1.1) cDNA clones encoding functional CA enzymes were isolated from a nonphotosynthetic cotton tissue. The role of CA in photosynthetic tissues have been well characterized, however there is almost no information for the role of CA in nonphotosynthetic tissues. A survey of relative CA transcript abundance and enzyme activity in different cotton organs revealed that there was substantial CA expression in cotyledons of seedlings and embryos, both nonphotosynthetic tissues. To gain insight into the role(s) of CA, I examined CA expression in cotyledons of seedlings during post-germinative growth at different environmental conditions. CA expression in cotyledons of seedlings increased from 18 h to 72 h after germination in the dark. Seedlings exposed to light had about a 2-fold increase in CA activities when compared with seedlings kept in the dark, whereas relative CA transcript levels were essentially the same. Manipulation of external CO2 environments [zero, ambient (350 ppm), or high (1000 ppm)] modulated coordinately the relative transcript abundance of CA (and rbcS) in cotyledons, but did not affect enzyme activities. On the other hand, regardless of the external CO2 conditions seedlings exposed to light exhibited increase CA activity, concomitant with Rubisco activity and increased chlorophyll content. Our data revealed that steady-state levels of CA and rbcS transcripts are regulated at the transcriptional level in response to external CO2 conditions, while CA and Rubisco activities are modulated at the post-transcriptional level by light. Thus CA expression in cotyledons during post-germinative growth may be to “prime” cotyledons for the transition at the subcellular level for the transition from plastids to chloroplasts, where it provides CO2 for Rubisco during photosynthesis. Furthermore, CA expression increased during embryo maturation similar to oil accumulation. Specific sulfonamide inhibitors of CA activity significantly reduced the
rate of [14C]-acetate incorporation into total lipids in cotton embryos and tobacco leaves and cell suspensions in vivo and in vitro. Similar results were obtained in chloroplasts isolated from leaves of transgenic CA antisense-suppressed tobacco plants (5% of wildtype activity). Collectively, these results support the notion that CA plays several physiological roles in nonphotosynthetic tissues.
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LEDBETTER, CRAIG ALLEN. "HERITABILITY OF SALT TOLERANCE DURING GERMINATION AND EMERGENCE IN SHORT STAPLE COTTON (GOSSYPIUM HIRSUTUM L.)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183961.
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Soil salinity is a serious problem for farmers in irrigated agriculture. Soil salts cause reduced stands and yields because of toxic ion and osmotic problems for surviving seedlings. The tolerance to sodium chloride during germination and emergence was studied in three commercial cultivars of short staple cotton (Gossypium hirsutum L.). It is this stage of the life cycle that cotton is most sensitive to salts in the soil solution. The objectives of this study were to increase the tolerance to sodium chloride during germination and emergence and to determine the narrow sense heritability of this factor. Parental cultivars initially demonstrated 15% emergence at -1.2 MPa NaCl. Surviving salt tolerant plants were planted in the field and seeds from these plants were used as the germplasm for the next cycle of salt tolerance selection. Experiments were conducted to determine the relative salt tolerance of all plants at -1.2, -1.4, -1.6, and -1.8 MPa NaCl. Emergence of salt tolerant accessions from the first cycle of selection ranged from 3.1 to 25.8% in the first relative salt tolerance experiment. The average emergence of all accessions taken over all four salinity levels was 8.9% for first cycle plants. After a second cycle of selection for salt tolerance, the average emergence percentage increased to 13.0% over the four salinity levels. Emergence ranged from 0.7 to 32.6% in the second relative salt tolerance experiment. Narrow sense heritability of sodium chloride tolerance during germination and emergence was estimated at 0.38 using data from the first and second relative salt tolerance experiments.
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Villamar, Torres Ronald Oswaldo. "Genetic study of topping-induced cotton/Gossypium hirsutum/ L. plant defense reactions, combining : Bioinformatics, VOC capture and genic expression." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG073.
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Gossypium hirsutum, le coton Upland, représente plus de 95% de la fibre de coton produite annuellement dans le monde et est cultivé dans environ 40 pays. La protection des champs de coton contre l’attaque des arthropodes herbivores nécessite des quantités importantes d’insecticides de synthèse, environ 18% de la consommation mondiale en 2000, bien que cela ait beaucoup diminué grâce au coton Bt et aux programmes d’éradication de certains ravageurs. Les composés organiques volatils (COV) naturellement émis par les plantes cultivées peuvent réduire les attaques d'insectes, les COV ayant une influence sur le comportement des arthropodes herbivores et des arthropodes auxiliaires. La recherche scientifique sur les COV des plantes a beaucoup augmenté depuis deux ou trois décennies. La stimulation des émissions de COV dans les champs de coton est désormais recommandée par les entomologistes du Cirad en tant que composante de la stratégie de protection. L’écimage (topping en anglais), c'est-à-dire couper la tête des cotonniers au cours de la floraison, stimule l'émission de COV de défense, une protection écologique qui limite les risques pour la santé dus aux insecticides synthétiques, pour les agriculteurs et les personnes des environs. L'objectif de la thèse était d'améliorer nos connaissances sur les bases génétiques des émissions de COV après l’écimage. La combinaison de plusieurs disciplines telles que la bio-informatique, l'écologie chimique et la génétique moléculaire nous a permis de: 1) analyser les séquences génomiques des gènes des voies de biosynthèse des COVs terpènes et terpénoïdes et des facteurs de transcription (TF) liés à la réponse au stress, à l'aide des bases de données publiées sur les génomes de trois espèces de coton, G. raimondii, G. arboreum (cotons diploïdes) et G. hirsutum (coton tétraploïde), 2) étudier les émissions de COV par les feuilles de coton des plants de G. hirsutum en réponse à l’écimage, en capturant ces molécules en serre et en caractérisant leurs profils cinétiques par chromatographie en phase gazeuse-spectrométrie de masse (GC-MS), incluant des mesures quantitatives, et 3) étudier les modifications de l'expression ARN des plants de coton G. hirsutum après l’écimage, pour 44 gènes impliqués dans la biosynthèse des COV, et également par une comparaison du transcriptome complet au moyen d'une analyse RNA-seq. Les résultats des trois domaines scientifiques, bio-informatique, analyse chimique et expression des gènes, ont pu être liés dans notre thèse de recherche: par ex., deux des gènes initialement identifiés par la bio-informatique, correspondant à deux enzymes, TPS50 (EC: 4.2.3.106 - (E ) bêta-ocimène synthase) et TPS16 (EC: 4.2.3.111 - alpha-terpinéol synthase), ont montré une augmentation de leur expression après l’écimage, et l'analyse GC-MS montre une modification correspondante des profils d'émission de COV. Ces mêmes composés avaient déjà été caractérisés dans d'autres plantes en réponse aux dégâts d’arthropodes. Ce travail de thèse constitue une première exploration des bases génétiques des émissions défensives de COV par les cotonniers cultivés G. hirsutum. La variabilité des comportements d’expression génique observés entre les trois génotypes étudiés de coton Upland africain G. hirsutum, permet de supposer qu’une diversité génétique est présente pour les émissions défensives de COV, ce qui pourrait permettre d’améliorer et d’adapter ces mécanismes de défense naturels et leur réponse à l’écimage, dans la perspective d'une protection naturelle plus efficace des champs de cotonGossypium hirsutum, the Upland cotton, represents more than 95% of the cotton fiber annually produced worldwide and is grown in about 40 countries. The protection of cotton fields against the attack of herbivorous arthropods needs important quantities of synthetic insecticides, around 18% of the world consumption for the year 2000, although this decreased very much thanks to Bt cotton and eradication programs for some pests. Volatile organic compounds (VOCs) naturally emitted by crop plants can reduce insect attacks through the influence of VOCs on the behaviors of herbivorous arthropods and auxiliary arthropods. Scientific research about plant VOCs has been increasing much since two or three decades. The stimulation of VOCs emissions by cultivated cotton plants is now recommended by entomologists of CIRAD as a component of the cotton fields protection strategy. “Topping", that is, cutting the head of the cotton plants during the useful floriferous period, stimulates the emission of defense VOCs. It is an environmentally friendly method and it limits health hazards due to the use of synthetic insecticides for the farmers and the surrounding human populations. The objective of the thesis was to improve our knowledge about the genetic bases of VOCs emissions after topping. The combination of several disciplines such as bioinformatics, chemical ecology and molecular genetics allowed us to: 1) analyze the genomic sequences of VOCs genes of the terpene and terpenoid biosynthesis pathways and transcription factors (TF) related to stress response, using the published genome databases of three cotton species, G. raimondii, G. arboreum (both diploid cottons) and G. hirsutum (tetraploid cotton), 2) study the VOCs emissions by cotton leaves of G. hirsutum plants in response to topping, by capturing these molecules in greenhouse and then characterizing their kinetic profiles by means of gas-chromatography mass-spectrometry (GC-MS), with quantitative measurements, and, 3) study the modifications of the RNA expression of G. hirsutum cotton plants after topping, for genes involved in VOCs biosynthesis through quantitative PCR measurements on 44 targeted genes and also by means of a whole-transcriptome comparison through an RNA-seq analysis. The results from the three different fields, bioinformatics, chemical analysis and gene expression, could be interrelated in our research thesis: e.g., two of the genes initially identified by bioinformatics, corresponding to two enzymes, TPS50 (EC: 4.2.3.106 - (E) -beta-ocimene synthase) and TPS16 (EC: 4.2.3.111 - alpha-terpineol synthase), were shown to increase their expression after topping, while the GC-MS analysis showed an modification of the corresponding VOCs in emission profiles. These compounds have been already characterized in other organisms in response to wounds produced by herbivorous insects. This thesis work is a first exploration of the genetic bases of defensive VOCs emission by G. hirsutum cultivated cottons. The variability of genic expression behaviors observed amongst the three genotypes of African Upland cotton G. hirsutum that were studied permits to hypothesize that a genetic diversity is present for defensive VOCs emissions, that could permit to improve and adapt by breeding these natural defense mechanisms and the response to topping, in perspective of a more efficient natural protection of cotton fields
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Ribeiro, Victor Alves. "Caracterização genética de atributos do desenvolvimento radicular em algodoeiro herbáceo (Gossypium hirsutum L.)." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4489.
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The objective of this study was to evaluate and characterize root growth in cotton genotypes, and identify the most appropriate time to evaluate the related traits in rhizotrons systems. It was also tried to estimate the genetic parameters inherent in these traits, among which were included the total length, surface area, total volume and average diameter of roots. Thus, two different studies were developed. The first consisted in an experiment to characterize ten cotton genotypes, in rhizotrons. This experiment was conducted in randomized block design with split plot in time, and four replications. Six evaluations were made per plots, at 7, 14, 21, 28, 35 and 42 days after seedling emergence. Each measure was resulted of the image captured from a rhizotron (experimental unit). The variance analysis was made, and Scott & Knott test was used to cluster the genotype means. Linear regression analysis was performed to evaluate the time effect within genotypes. The phenotypic, genotypic and environmental correlations between each pair of traits were also estimated. The daily root growth per genotype was also observed, applying the same method of mean grouping for the genotypic discrimination. The second study was also conducted in rhizotrons system, in order to estimate the genetic parameters related to the same traits. Two crosses were performed involving contrasting parents: CD 408 x CNPA GO 2008-1265 and CD 408 x CNPA GO 2007-423. Each cross was assessed in a different experiment conducted as completely randomized design with six treatments (parents, and F1, F2, RC1 and RC2 generations). The data analysis allowed identifying outstanding genotypes for each trait, as well as the most appropriate time for the respective assessment. It was found high correlations among the evaluated traits. The estimation of genetic parameters allowed approximate inferences about the minimal number of genes involved in the genetic control of these traits. The main conclusions were: i) there is genetic variability in the evaluated characters related to development and growth of root in cotton upland; ii) the evaluation of these traits at 35 days after seedling emergence enables better genetic discrimination for selection purposes; iii) the lines CNPA GO 2008-1265 and CNPA GO 2002-2043 are predominantly superior than other genotypes, especially in the total length root; iv) CNPA GO 2007-423 genotype is outstanding in relation to others by its higher total volume of roots; v) there are high genetic associations among the traits total length, total area, total volume, and total diameter of roots; and vi) the estimated number of genes involved in the genetic control of these traits indicate oligogenic inheritance, although there is also evidence of strong environmental influence, suggesting also the possibility of polygenic or mixed inheritance (major genes and polygenes).
O objetivo deste trabalho foi avaliar e caracterizar o crescimento radicular em genótipos de algodoeiro, bem como identificar o tempo mais adequado para avaliação de caracteres relacionados, em sistema de rizotrons. Também buscou-se estimar parâmetros genéticos inerentes a esses caracteres, dentre os quais se incluíram comprimento total, área superficial, volume total e diâmetro médio de raízes. Para isso, foram conduzidos dois estudos independentes. O primeiro deles constituiu-se num experimento para a caracterização de dez genótipos de algodoeiro, em rizotrons, sob o delineamento de blocos ao acaso com parcelas subdivididas no tempo, e quatro repetições. Foram realizadas seis avaliações (medidas repetidas) por parcela, aos 7, 14, 21, 28, 35 e 42 dias da emergência das plântulas. Cada medida resultou da captura de uma imagem do sistema por rizotron (unidade experimental). Foi, então, realizada a análise da variância e aplicou-se o teste Scott & Knott para agrupamento das médias de genótipos. Também foi empregada análise de regressão para avaliar o efeito da fonte de variação “tempo” dentro de genótipos. Estimaram-se ainda as correlações fenotípica, genotípica e de ambiente entre os caracteres avaliados. Também avaliou-se a taxa de crescimento radicular diária por genótipo, aplicando-se o mesmo teste de agrupamento de médias para a discriminação genotípica. O outro estudo foi conduzido, também em rizotrons, visando estimar parâmetros genéticos associados aos mesmos caracteres. Realizaram-se dois cruzamentos envolvendo genitores contrastantes: CD 408 x CNPA GO 2008-1265 e CD 408 x CNPA GO 2007-423. Cada cruzamento correspondeu a um ensaio em delineamento inteiramente casualizado, com seis tratamentos (os genitores e as gerações F1, F2, RC1 e RC2). A análise dos dados permitiu identificar genótipos superiores em relação aos caracteres avaliados, bem como um momento mais adequado para a sua avaliação. Houve correlações significativas e de elevada magnitude entre os caracteres avaliados. E a estimação de parâmetros genéticos permitiu inferir aproximadamente sobre o número mínimo de genes envolvidos no controle genético dos caracteres. As principais conclusões foram: i) há variabilidade genética nos caracteres avaliados inerentes ao crescimento e desenvolvimento radicular do algodoeiro; ii) a avaliação desses caracteres aos 35 dias após a emergência possibilita melhor discriminação genotípica para fins de seleção; iii) as linhagens CNPA GO 2008-1265 e CNPA GO 2002-2043 são predominantemente superiores aos demais genótipos avaliados, sobretudo no caráter comprimento total de raízes; iv) na época de avaliação indicada (35 dias) o genótipo CNPA GO 2007-423 destaca-se pelo seu maior volume total de raízes; v) há alto grau de associação genética entre os caracteres comprimento total de raízes, área total de raízes, volume total de raízes e diâmetro médio de raízes; e vi) o número estimado de gene envolvidos no controle genético dos caracteres sugere herança oligogênica, embora haja também indícios de forte influência ambiental, o que abre a possibilidade de herança poligênica ou, até mesmo, herança mista (genes de efeitos maiores e poligenes).
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Thornby, David. "Using new computational tools to investigate the responses of cotton plants (Gossypium Hirsutum L.) to defoliation /." [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18076.pdf.
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Gérardeaux, Edward. "Adjustment of phenology, growth and dry matter production of cotton (Gossypium Hirsutum L.) facing potassium deficiency." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13851/document.
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La déficience en potassium dans les parcelles de cotonnier est un phénomène répandu et en recrudescence. Le problème est d’autant plus marqué en Afrique sub-saharienne que les sols sont pauvres et les systèmes de culture peu intensifs. Les principaux effets de la carence en potassium référencés dans la littérature sont une réduction de la surface foliaire, une réduction de l’assimilation et une modification des règles de répartition des assimilats entre les compartiments de la plante (tiges, racines, fruits et feuilles). Les connaissances à l’échelle cellulaire sur le rôle du potassium sont nombreuses mais paradoxalement peu de modèles permettent l’intégration de ces résultats à l’échelle du plant et du peuplement. La raison provient de la multiplicité des mécanismes affectés et de la complexité à les intégrer à l’échelle du plant ou du peuplement. L’objectif de notre travail est de caractériser les effets de la carence en K sur la croissance et le développement du cotonnier avec suffisamment de variables intermédiaires explicatives pour pouvoir proposer un schéma conceptuel compatible avec les concepts utilisés dans les modèles de croissance de cette plante. Cet objectif implique ainsi de porter nos investigations à plusieurs échelles (peuplement, plante, organes, organites) et sur des variables-clés du fonctionnement physiologiques des plantes utilisées dans la modélisation courante telles que la photosynthèse ou le statut hydrique. Nos recherches nous ont aussi amené à mesurer d’autres variables non inclues dans les modèles courant, afin d’affiner notre compréhension du fonctionnement des plantes carencées (teneurs en sucres, vitesses de carboxylation, ouvertures stomatiques …). Pour satisfaire à ces objectifs, deux types complémentaires d’expérimentations ont été menés : 1) des essais en pleins champs, en condition pluviale strictes ont été conduits au Bénin, deux années de suite, sur deux sites différents : à Aplahoué en 2004 et à Savalou en 2005. Il s’agit d’essais comparant différents niveaux de fertilisation en potassium. L’objectif de ces essais était d’étudier les effets de la carence à l’échelle du peuplement. 2) Par la suite, une expérimentation en serre et en hydroponie a été conduite (Bordeaux, 2006) dans l’objectif d’analyser finement les processus affectés à l’échelle du plant et de l’organe. Les essais en peuplement comme l’essai en serre ont permis d’obtenir des gammes de teneur en potassium variées, grâce à des niveaux d’alimentation variés (3 niveaux au champ, 4 en serre). Les teneurs planchers des plantes les plus carencées se situaient aux alentours de 8 à 10 mg Kg-1, ce qui contraste avec les teneurs maximum mesurées qui avoisinaient les 30 mg g-1. L’indice foliaire des traitements carencés des essais en peuplement est inférieur aux témoins en raison d’un moins grand nombre de feuilles et d’une taille individuelle réduite. Dans les essais en serre, une importante réduction de la surface foliaire est aussi observée mais la part de la réduction de la surface individuelle dans la réduction de la surface totale est plus prononcée. L’analyse des dynamiques de croissance des surfaces foliaires montre que l’accroissement relatif des feuilles est identique quel que soit les niveaux de carence mais que la taille des organes à l’émergence est plus petite pour les plants carencés. En revanche, les entrenœuds des plants carencés ont à la fois une taille réduite à l’émergence et une croissance relative plus faible. A l’échelle du peuplement aucune différence d’efficience de conversion de la lumière n’est observée en conséquence, les réductions de biomasse sèche observée sont entièrement dues à une diminution de l’efficience d’interception du rayonnement. En revanche, l’efficience de conversion du rayonnement interceptée de l’essai en serre est affectée par la carence en K mais uniquement pour le traitement le plus carencéPotassium deficiency is a common phenomenon in cotton parcels. This problem is quite important in sub-Saharan Africa, where soils are poor and cropping systems are very low intensive. The main effects of potassium deficiency referenced in scientific literature are: (a) a reduction in leaf area, (b) a decrease in nutrient assimilation, and (c) a modification of nutrient repartition amongst compartments (i.e. stems roots, fruits, and leaves). Even though knowledge at the cellular level on the role of potassium is wide, ironically, only but a few models integrate results at the plant or stand levels. The reason comes from the multiplicity of mechanisms used and the complexity of integrating them throughout the plant or stand. The objective of our work is to characterize the effects of K-deficiency on the growth and development of cotton plants by including sufficient intermediate explanatory variables to provide a comparable scheme with the concepts used in growth models for this plant. This objective implies that our research focuses on different scales (i.e. stand, plant, organ, cell) and on physiological variables used in current models such as photosynthesis or water status. Our research had also led us to measure other variables not included in current models, to refine our understanding of the mechanisms of how deficient plants grows (i.e. sugar rates, carboxylation speed, stomata opening…). To meet these objectives, two complementary types of experiments were conducted: (i) field trials were performed in Benin on two different sites, Aplahoué in 2004 and Savalou in 2005, with strict rainfall conditions to compare different levels of potassium-fertilization and describe the effects of K-deficiency at the stand level. (ii) and a greenhouse hydroponic experiment was done in Bordeaux, France in 2006 to analyze the processes used throughout the plant and the organ. The field and the greenhouse tests had different levels of potassium fertilisation (2 to 3 levels in the field, 4 in the greenhouse) and gave us wide ranges of potassium contents in leaves. The minimum value of the leaf K content for the deficient plants were around 8 to 10 mg kg-1, which contrasts with the maximum values measured that were around 30 mg g-1. Potassium levels for the most deficient plants were around 8 to 10 mg Kg-1, while the highest levels measured were 30 g Kg-1. The leaf area index of deficient treatments is inferior to that of controls due to a lower number of leaves and smaller leaf sizes. In the greenhouse test, an important decrease of leaf area is observed but the proportion of the reduction due to a reduction in individual leaf size is more pronounced than in the filed experiments. The temporal analysis of the leaf area growth shows that the relative increase in size of the individual leaves is the same whatever the level of K-deficiency but that the size of the organs at emergence from apical buds is smaller for K-deficient plants. In counterpart, internodes of K-deficient plants have smaller lenght at emergence and a decreased relative growth rate. At stand level, no difference of light conversion efficiency is observed. As a result, observed reductions of dry biomass are essentially due to a decrease in light interception. However, radiation use efficiency in greenhouse tests are affected by K-deficiency but only for the most K-deficient treatment. Measures on gas exchanges made in greenhouse experiment also shows that photosynthesis is affected only for the most K-deficient treatments. This reduction is due to two concomitant effects: poor stomatal opening and a reduction in the maximum velocity of carboxylation. The relative distribution in biomass for all the tests is modified by the potassium-deficiency, benefiting leaves at the expense of the heterotrophic organs. This effect is observed at the plant level through an increase in the specific leaf weight and a relative decrease in stem and root biomass
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Collins, Guy David. "Reducing Costs and Optimizing the Timing of Agronomic Inputs for Cotton (Gossypium hirsutum L.) in North Carolina." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-09182009-043001/.
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Cotton (Gossypium hirsutum L.) grown in North Carolina requires intensive management for achieving optimal yields in an early-season environment. Recent increases in production costs require cotton producers to adopt practices that allow yield potential to be reached, while reducing input costs or optimizing the timing of agronomic inputs. Six experiments were conducted in North Carolina from 2006 to 2008 to investigate various production practices that could potentially reduce production costs and to define optimal timings of agronomic inputs. The first experiment investigated precision application of in-furrow insecticides for cotton planted in a hill-dropped configuration. The second experiment investigated application rates and timings of mepiquat chloride (MC) for cotton grown in conditions that promote excessive vegetative growth. The third experiment investigated the effects of MC applied at various rates and timings on the correlation (regression) between two techniques for measuring light interception and canopy coverage: the light quantum sensor method and the overhead digital imagery method. The fourth experiment investigated the effects of MC applied at physiological cutout, in terms of defoliation, regrowth, maturity, and yield. The fifth experiment investigated the effects of preconditioning defoliation treatments for tall cotton portraying dense canopies which improve standard defoliation practices and the timeliness of harvest. The sixth experiment investigated the effects of ethephon rate in defoliant mixtures on harvest date, with regard to defoliation timing and prior MC treatment.
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Guo, Yufang. "Quantitative genetic analysis for flowering time in primitive Upland cotton, Gossypium hirsutum L., and chromosome assignment of BAC-derived SSR markers." Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11062007-142438.
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Bogiani, Julio Cesar [UNESP]. "Comportamento de cultivares de algodoeiro (Gossypium hirsutum L.) ao uso de diferentes doses de cloreto de mepiquat." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/86358.
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O experimento foi conduzido de janeiro a abril de 2007 sob condições de casa de vegetação. O objetivo foi avaliar o comportamento de cultivares de algodão submetidas a doses de cloreto de mepiquat e, ainda, verificar se a resposta está ligada ao ciclo ou arquitetura da cultivar. Os tratamentos foram constituídos de seis cultivares com comportamento de crescimento e diferentes ciclos produtivos (FiberMax 966, FiberMax 977, DeltaPenta, DeltaOpal, FMT 501 e FMT 701), bem como, a utilização de quatro doses do regulador vegetal a base de cloreto de mepiquat (PIX®): 7,5; 15,0 e 22,5 g ha-1 de i.a e a testemunha sem aplicação do produto. Foram utilizados vasos de 12 litros de capacidade, sendo cultivadas duas plantas por vaso. O delineamento experimental utilizado foi em blocos casualizados com quatro repetições em esquema fatorial 4 doses x 6 cultivares. As avaliações constituíram da: altura de plantas, número de ramos reprodutivos, massa de matéria fresca e massa de matéria seca, retenção de estruturas reprodutivas e área foliar. Para cada cultivar, foi calculada a relação entre taxa de crescimento em altura e concentração do regulador. Os resultados mostraram que o crescimento das plantas de algodoeiro em altura é diminuído com a aplicação foliar de cloreto de mepiquat, sendo maior a redução de altura, quanto maior a quantidade de regulador aplicada. Existe diferença entre as cultivares estudadas quanto à sensibilidade ao regulador, de modo que as mais precoces são mais sensíveis. Para a mesma dose aplicada, a concentração de regulador vegetal na planta é diferente, pois a quantidade de produto depositada na folha de cada cultivar é também diferente. O regulador não afetou a taxa de assimilação de CO2 das cultivares de algodão estudadas.
The experiment was conducted between January and April 2007 under greenhouse conditions. The objective to evaluate the behavior of cotton cultivars submitted to the doses of Mepiquat Chloride, and also to find if the answer is linked to the cycle or architecture of cultivar. The treatments were constituted of six cultivars of different behaviour about its growth and cycle (FiberMax 966, FiberMax 977, DeltaPenta, DeltaOpal, FMT 501 e FMT 701); and four doses of the plant growth regulator, mepiquat chloride (PIX®): 7,5, 15,0, 22,5 g ha-1 and a control (0,0 g ha-1). Plots of 12 liters of capacity were used with two plants per plot. The experimental design used was the completely randomized with four replications in outline factorial 4 doses x 6 cultivars. The parameters analyzed were: height of plants, number of reproductive branches, weight of dry matter, retention of reproductive structures, and leaf area. Also, it was calculated for each cultivar, the relationship among growth rate in height and concentration of the regulator. The results showed that the growth of cotton plants in height is reduced by application of mepiquat chloride, and the height reduction is larger, as larger the amount of plant growth regulator applied. There is difference among the cultivars studied for sensitivity to the plant growth regulator, so that the earliest cultivars are more sensitive. In the same applied dose, the concentration of plant growth regulator in the plant is different because the amount of product deposited on the left of each cultivar is different too. The mepiquat chloride didn’t affect the assimilation rate of CO2 to the cotton cultivars studied.
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SOUSA, Romero de Lima. "Avaliação de competição entre pólen nas espécies de algodoeiros Gossypium hirsutum L. e G. mustelinum (Miers) Watt." Universidade Federal Rural de Pernambuco, 2010. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6506.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The Brazilian Northeast is the center of origin of cotton Gossypium mustelinum (Miers) Watt. This cotton has not been improved or exploited commercially, but there is evidence of their introgression into the genome of varieties of upland cotton G. hirsutum L. variety marie galante Hutch. When considering the loss of variability can be said that G. mustelinum, G. barbadense L. and G. hirsutum L. var. marie galante Hutch of extinction are very high, high and medium, respectively, requiring immediate efforts for their preservation. This study aims to determine whether there is competition between pollen G. mustelinum and herbaceous in relation to fertilization of wild species, as well as whether there are differences of competition in different proportions of pollen of these species. For both crossings were performed between the two species used the G. mustelinum mother as having been fertilized by pollen from: i) mixture of 50% G. mustelinum and 50% herbaceous ii) a mixture of 75% herbaceous and 25% G. mustelinum iii) a mixture of 25% herbaceous and 75% G. mustelinum iv) herbaceous v) G. mustelinum. The latter two were used as controls to determine the expression pattern of alleles in polyacrylamide gels and validate the crosses with mixed pollen. We obtained seeds from each cross. The molecular analysis determined the proportion of seeds from crosses inter-and intra-specific by genotyping with SSR markers of the type. The frequency of offspring in each proportion of pollen used in crosses were compared using statistical test, chi-square (x²), with expected frequencies of 50% of hybrid seeds and 50% of seeds derived from selfing, 75% of seeds hybrid and 25% of the seeds of self-fertilization, 25% seed and 75% hybrid seed selfing. Were pollinated between 10:42 Flowers in the crosses with mixed pollen. The average number of seeds obtained ranged between nine and 11. Comparing these values with the average number of seeds from the intersection with 100% of pollen of the respective species, it was found that there was little variation. There were no differences in fertility or crossability between the genotypes of G. mustelinum. The only male parent in crosses that did not get the seeds was C27, and this was possibly caused by physiological conditions unfavorable. Through the data can be seen that the higher the percentage of pollen from G. hirsutum, the greater tendency of hybrids between two species. Therefore the higher the percentage of pollen from G. mustelinum, the lower the amount of hybrids. After analyzing the results, the chi-square (x²), a 1% probability it was established that there was competition between pollen from wild species and cultivated at all levels studied.
O Nordeste brasileiro é o centro de origem do algodão Gossypium mustelinum (Miers) Watt. Esta espécie ainda não foi melhorado ou explorado comercialmente, entretanto há evidências de sua introgressão no genoma das variedades de algodoeiro herbáceo G. hirsutum L. variedade marie galante Hutch. Ao considerar a perda de variabilidade pode-se afirmar que G. mustelinum, G. barbadense L. e G. hirsutum L. variedade marie galante Hutch estão com risco de extinção muito alto, alto e médio, respectivamente, necessitando de esforços imediatos para sua preservação. Este trabalho tem por finalidade verificar se há competição de pólen entre G. mustelinum e herbáceo em relação à fertilização da espécie silvestre, bem como se há diferença de competição em diferentes proporções de polens das referidas espécies. Para tanto, foram realizados cruzamentos entre as duas espécies, utilizado o G. mustelinum como genitor feminino tendo sido fecundado por pólen de: i) mistura de 50% herbáceo e 50% de G. mustelinum; ii) mistura de 75% herbáceo e 25% de G. mustelinum; iii) mistura de 25% herbáceo e 75% de G. mustelinum; iv) herbáceo e v) G. mustelinum. Estes dois últimos foram utilizados como controle para saber o padrão da expressão dos alelos nos géis de poliacrilamida e validar os cruzamentos com misturas de pólen. Foram obtidas sementes provenientes de cada cruzamento. Na análise molecular foi determinada a proporção de sementes provenientes de cruzamentos inter e intraespecíficos por meio da genotipagem com marcadores do tipo SSR. A frequência de descendentes em cada proporção de pólen usada no cruzamento foi comparada por meio de teste estatístico do qui-quadrado (x²), com frequência esperada de: 50% de sementes híbridas e 50% de sementes oriundas de autofecundação; 75% de sementes hibridas e 25% de sementes de autofecundação; 25% de sementes hibridas e 75% de sementes de autofecundação. Foram polinizadas entre dez e 42 flores nos cruzamentos com mistura de pólen. O número médio de sementes obtidas variou entre nove e 11. Comparando-se tais valores com o número médio de sementes provenientes do cruzamento com 100% de pólen das respectivas espécies, verificou-se que houve pouca variação. Não foi verificada diferenças de fertilidade ou de cruzabilidade entre os genótipos de G. mustelinum. Os únicos genitores masculinos nos cruzamentos que não obtiveram sementes foram o C27 e Mac 01, fato este ocasionado possivelmente por condições fisiológicas desfavoráveis. Por intermédio dos dados pode-se constatar que quanto maior a porcentagem de pólen de G. hirsutum, maior tendência de híbridos entre as duas espécies. Consequentemente, quanto maior a porcentagem de pólen de G. mustelinum, menor a quantidade de híbridos. Após análise dos resultados obtidos pelo teste de qui-quadrado (x²), a 1% de probabilidade, foi possível constatar que houve competição entre pólen da espécie silvestre e cultivada em todos os níveis estudados.
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Bogiani, Julio Cesar 1980. "Comportamento de cultivares de algodoeiro (Gossypium hirsutum L.) ao uso de diferentes doses de cloreto de mepiquat /." Botucatu : [s.n.], 2008. http://hdl.handle.net/11449/86358.
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Orientador: Ciro Antonio RosolemBanca: João Domingues Rodrigues
Banca: Luiz Henrique Carvalho
Resumo: O experimento foi conduzido de janeiro a abril de 2007 sob condições de casa de vegetação. O objetivo foi avaliar o comportamento de cultivares de algodão submetidas a doses de cloreto de mepiquat e, ainda, verificar se a resposta está ligada ao ciclo ou arquitetura da cultivar. Os tratamentos foram constituídos de seis cultivares com comportamento de crescimento e diferentes ciclos produtivos (FiberMax 966, FiberMax 977, DeltaPenta, DeltaOpal, FMT 501 e FMT 701), bem como, a utilização de quatro doses do regulador vegetal a base de cloreto de mepiquat (PIX®): 7,5; 15,0 e 22,5 g ha-1 de i.a e a testemunha sem aplicação do produto. Foram utilizados vasos de 12 litros de capacidade, sendo cultivadas duas plantas por vaso. O delineamento experimental utilizado foi em blocos casualizados com quatro repetições em esquema fatorial 4 doses x 6 cultivares. As avaliações constituíram da: altura de plantas, número de ramos reprodutivos, massa de matéria fresca e massa de matéria seca, retenção de estruturas reprodutivas e área foliar. Para cada cultivar, foi calculada a relação entre taxa de crescimento em altura e concentração do regulador. Os resultados mostraram que o crescimento das plantas de algodoeiro em altura é diminuído com a aplicação foliar de cloreto de mepiquat, sendo maior a redução de altura, quanto maior a quantidade de regulador aplicada. Existe diferença entre as cultivares estudadas quanto à sensibilidade ao regulador, de modo que as mais precoces são mais sensíveis. Para a mesma dose aplicada, a concentração de regulador vegetal na planta é diferente, pois a quantidade de produto depositada na folha de cada cultivar é também diferente. O regulador não afetou a taxa de assimilação de CO2 das cultivares de algodão estudadas.
Abstract: The experiment was conducted between January and April 2007 under greenhouse conditions. The objective to evaluate the behavior of cotton cultivars submitted to the doses of Mepiquat Chloride, and also to find if the answer is linked to the cycle or architecture of cultivar. The treatments were constituted of six cultivars of different behaviour about its growth and cycle (FiberMax 966, FiberMax 977, DeltaPenta, DeltaOpal, FMT 501 e FMT 701); and four doses of the plant growth regulator, mepiquat chloride (PIX®): 7,5, 15,0, 22,5 g ha-1 and a control (0,0 g ha-1). Plots of 12 liters of capacity were used with two plants per plot. The experimental design used was the completely randomized with four replications in outline factorial 4 doses x 6 cultivars. The parameters analyzed were: height of plants, number of reproductive branches, weight of dry matter, retention of reproductive structures, and leaf area. Also, it was calculated for each cultivar, the relationship among growth rate in height and concentration of the regulator. The results showed that the growth of cotton plants in height is reduced by application of mepiquat chloride, and the height reduction is larger, as larger the amount of plant growth regulator applied. There is difference among the cultivars studied for sensitivity to the plant growth regulator, so that the earliest cultivars are more sensitive. In the same applied dose, the concentration of plant growth regulator in the plant is different because the amount of product deposited on the left of each cultivar is different too. The mepiquat chloride didn't affect the assimilation rate of CO2 to the cotton cultivars studied.
Mestre
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Ferreira, Silvio Marcos. "O efeito do silício na cultura do algodoeiro (Gossypium hirsutum L.): aspectos bioquímicos, qualidade de fibra e produtividade." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-25072008-111614/.
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Inúmeros trabalhos evidenciam o efeito do silício nos processos, estruturas e características das plantas que ocorre em várias culturas. Supõe-se que tais efeitos possam estar associados à vários processos fisiológicos, dentre eles a melhoria da qualidade e produtividade, o favorecimento da fotossíntese e a redução de doenças. O presente trabalho tem por objetivo estudar os efeitos do silício nos aspectos bioquímicos, qualidade de fibra e produtividade do algodoeiro (Gossypium hirsutum L.) na cultivar BRS-Cedro, material amplamente cultivado na região dos cerrados do Brasil. Realizou-se um experimento em vasos com capaciadade de 3,2 litros de solução nutritiva de Johnson et al. (1957), modificada. As soluções nutritivas foram corrigidas para pH inicial igual a 6,0, continuamente arejadas e trocadas quinzenalmente. Conduziu-se o experimento em casa de vegetação, cujo delineamento estatístico foi inteiramente casualizado com seis tratamentos: (0, 10, 25, 50, 100 e 200) mg.L-1 de silício e 05 repetições. A fonte de silício utilizada nos tratamentos, com excessão da testemunha, foi o metassilicato de sódio (Na2SiO3.5H2O). Os parâmetros avaliados foram os seguintes: teor de silício foliar e radicular, teor de potássio, matéria seca, fotossíntese, transpiração, condutância estomática, e concentração interna de CO2; e após a colheita e beneficiamento para qualidade de fibra as amostras foram submetidas à análise de HVI (high volume instruments) e assim avaliados os seguintes parâmetros: % de fibra, peso de 100 sementes, peso de capulhos, comprimento da fibra, uniformidade no comprimento da fibra, índice de fibra curta, tenacidade da fibra, elongação, micronaire, maturidade da fibra, finura, teor de açúcar na fibra (deposição), reflectância, cor amarelada e tenaciadade do fio. O experimento comprendeu-se no período de abril a novembro de 2005, sendo o ciclo da semeadura até a colheita. As doses de silício utilizadas promoveram aumento considerável nos teores radiculares e foliares do algodoeiro. Os resultados das análises de laboratório evidenciaram interações positivas entre as doses utilizadas com a fotossíntese, transpiração, condutância estomática e concentração interna de CO2 e para os parâmetros de qualidade de fibra, somente houve interação positiva com o teor de açúcar na fibra, indicando promissor o uso de silício para a cultura. O decréscimo de açúcar na fibra afeta diretamente a qualidade, melhorando e impede o desenvolvimento do fungo Capnodium sp (fumagina), que também prejudica a fotossíntese.Several works clearly show the effect of silicon on plant processes, structures and characteristics. It is believed that they are associated to crop quality and yield, enhancing photosynthesis and increasing their resistance to diseases. In the present work effects of silicon on the biochemicals aspects, fiber quality and yield of cotton (Gossypium hirsutum L.), BRS-Cedro cultivar, widely cultivated in Brazilian savannahs, were evaluated. A greenhouse experiment using Johnson et al. (1957) modified nutrient solution in 3.2 liters pots, during a complete crop cycle from April to November of 2005, was carried out. Nutrient solutions were corrected to initial pH 6.0, with continuous aeration and biweekly substitution. Six rates of Si (0, 10, 25, 50, 100 and 200 mg L-1), as sodium metasilicate (Na2SiO3.5H2O), in a completely randomized design with five replications, were applied. During the cropping time leaf and root contents of Si and K, dry matter weight, photosynthesis, respiration, stomatal conductance and internal CO2 concentrations were assessed. After harvest and processing for fiber quality, HVI analyses were performed, and attributes such as percentage of fiber, weight of 100 seeds, cotton balls weight, fiber length and uniformity, short fiber index, tenacity, elongation, micronaire, maturity, thinness, sugar deposition on the fiber, reflectance, yellowish color and fiber tenacity were evaluated. Considerable increases in root and leaf contents of cotton as affected by applied Si rates were found, showing positive relationships among laboratory data with photosynthesis, respiration, stomatal conductance, and internal CO2 concentrations. Concerning the fiber quality, positive interaction was verified with sugar content in the fiber, indicating that Si application to cotton would be a promising cropping practice. Sugar decrease in the fiber improves its quality, hindering the development of the mushroom Capnodium sp, which also harms photosynthesis.
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Zamora, Diomides Santos. "Competitive interactions in a pecan (Carya illinoensis K. Koch)--cotton (Gossypium hirsutum L.) alleycropping system in the southern United States." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010056.
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Loison, Romain. "Analyse écophysiologique et modélisation de l’interaction génotype x environnement x itinéraire technique chez le cotonnier (Gossypium hirsutum L.) au Cameroun pour la conception d'idéotypes." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS174/document.
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La fibre de coton est la première fibre naturelle utilisée dans le monde. Le coton fournit un revenu à plus de 10 millions de personnes en Afrique occidentale et centrale. Au Cameroun, il est produit en conditions pluviales et le manque d'eau est le principal facteur abiotique limitant le rendement et la qualité de la fibre. Dans ce contexte, un programme de sélection a été initié en 1950 avec l'objectif d'augmenter le rendement, la qualité de la fibre et la résistance aux maladies. En 60 ans, plus de 20 cultivars ont été créés. Cependant, depuis une trentaine d'année, un plafonnement du rendement en coton graine est constaté. Cette étude a analysé la croissance et le développement des principaux cultivars vulgarisés de 1950 à nos jours, pour évaluer le progrès génétique, y compris celui de caractères d'adaptation au stress hydrique indirectement sélectionnés. Elle a analysé les interactions génotype x environnement x pratiques culturales (GEI) dans des conditions hydrique limitantes afin de pouvoir utiliser un modèle de simulation de la croissance du cotonnier. En utilisant ce dernier, les rendements ont pu être prédits et des idéotypes pour les conditions de culture du coton au Cameroun ont été conçus. Une application de ces travaux a été d'identifier des caractères d'adaptation au stress hydrique pour aider les sélectionneurs à choisir les cultivars qui résistent mieux au stress hydrique. Dans un premier temps, le progrès génétique et son interaction avec les conditions de culture au Cameroun ont été évalués au champ et en milieux contrôlés sur le développement du coton, la croissance (y compris racinaire), le rendement et la qualité de la fibre. Les résultats ont montré que la sélection a réussi à améliorer le potentiel de rendement et de qualité de la fibre lorsque la culture atteint la maturité physiologique, avant la fin de la saison des pluies. Cependant, lors de stress hydrique de fin de cycle, le programme de sélection a réduit la qualité de la fibre. La plupart des variables de développement et de croissance n'ont pas changé avec le temps, sauf le nombre de feuilles qui a été réduit. La sélection a créé des cultivars avec un meilleur potentiel de production et de qualité de fibres mais en perdant en plasticité en conditions sub-optimales et n'a pas amélioré l'accès à l'eau du sol. Dans un second temps, les analyses des GEI des caractères d'adaptation à la sécheresse ont montré que le déficit en eau a un impact négatif sur presque toutes les fonctions de la plante, à la fois au champ et en milieux contrôlés. Le cultivar récent L484, créé pour la zone de production la plus sèche, a maintenu le plus haut niveau de photosynthèse et de transpiration par unité de surface foliaire dans les conditions défavorables, maintenant ainsi le plus haut niveau d'efficience d'utilisation du rayonnement et de l'eau. Cependant, cela n'a pas permis d'améliorer la biomasse, l'indice de récolte et le rendement de ce cultivar. Le programme de sélection du coton au Cameroun a réussi à fournir un cultivar (L484) mieux adapté aux conditions locales, avec une plus grande stabilité et un développement plus rapide, mais sans aucune augmentation de rendement. Dans un dernier temps, le modèle de simulation de la croissance du cotonnier, CROPGRO-Cotton, a été utilisé afin de définir les idéotypes conduisant à des rendements plus élevés. Des expériences de terrain au Cameroun ont été utilisées pour constituer l'ensemble de données minimum pour l'étalonnage du modèle. Les cultivars AC, L484 et quarante-deux cultivars virtuels avec ± 20% par rapport aux valeurs de paramètres de L484 ont été comparés dans 99 années de temps généré en deux lieux. Par rapport à L484, les idéotypes avaient une durée réduite entre levée et floraison et plus longue de phase reproductive, un plus haut niveau de photosynthèse maximum avec des feuilles plus épaisses, et des feuilles plus petites pour la région de l'Extrême Nord ou plus grandes pour la région du NordCotton lint is the first natural fiber used in the world. Cotton provides income to more than 10 million people in West and Central Africa. In Cameroon, it is produced in rainfed conditions and water shortage is the major abiotic factor limiting yield and lint quality. In this context, a breeding program was initiated in 1950 to increase lint yield, fiber quality and disease resistance. After 60 years, this program has released more than 20 cultivars. However, seed cotton yield has been levelling off for more than thirty years.This study analyzed growth and development of main cultivars released from 1950 to-date to evaluate genetic gain including drought adaptation traits indirectly bred for. It also analyzed genotype by environment by crop management interactions (GEI) under water limited conditions in order to use a cotton simulation model in Cameroonian conditions. Then, crop simulation model was used to design cotton ideotypes under Cameroonian cropping conditions. An application of this work was in providing key drought adaptation traits to breed for cultivars that better withstand water stress.Firstly, phenotype evolution over breeding time and its interaction with cropping conditions in Cameroon was evaluated on cotton development, growth (including roots), yield, and fiber quality. Ten major cultivars were studied under rainfed conditions (field) and controlled conditions (greenhouse and phytotron). Classical GEI analysis of variance of cultivars and regression over their respective year of release were done. The results showed that the breeding program succeeded in improving cotton lint yield and the potential of fiber quality when the crop reached physiological maturity before the end of the rainy season. In late season drought, breeding reduced the fiber quality (fiber length, uniformity and strength). Most of the development and growth variables did not change with time, except the number of leaves which reduced. Breeding created cultivars with better potential fiber production and quality, but with reduced plasticity to sub-optimal environments and access to soil water. Secondly, an analysis of GEI for ecophysiological traits conferring a good response to drought was done in good and water limited conditions for a subset of four cultivars. The results indicated that water deficit had a negative impact on almost all plant functions, both under field and controlled environments. The recent cultivar L484 bred for the driest production area had the fastest development, thickest leaves with most chlorophyll and thus maintained the highest level of photosynthesis and transpiration per unit of leaf area in water-limited conditions. In these conditions, L484 had the highest radiation use efficiency and water use efficiency maintenances. Despite these traits this cultivar did not show any improvement in terms of biomass, harvest index and cotton yield across water conditions. Cotton breeding program in Cameroon succeeded in providing a cultivar (L484) better adapted to local conditions, with a higher stability and faster development coupled with a strategy of growth maintenance, without any improvement in yield. Thirdly, the crop simulation model CROPGRO-Cotton was used in order to design ideotypes with higher yield than existing cultivars. Field experiments in Cameroon were used to constitute the minimum dataset for the crop model calibration. Then, cultivars AC, L484 and forty-two virtual cultivars with ±20% from L484 parameter values were compared across 99 years of generated weather in two locations. Compared to L484, the cotton ideotypes in Cameroonian rainfed conditions had reduced emergence to anthesis duration, longer reproductive duration, higher maximum level of photosynthesis with thicker leaves, and smaller leaves for Far North region or bigger ones for North region
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Eldon, Simon. "A comparative study of the resistance mechanisms of upland cotton (Gossypium hirsutum, L.) to Fusarium oxysporum f.sp. vasinfectum and Verticillium dahliae." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283652.
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Queiroz, Damião Raniere. "Análise genética para caracteres agronômicos e tecnológicos de fibra em genótipos de algodoeiro herbáceo (Gossypium hirsutum L. var. Latifolium Hutch.)." Universidade Estadual da Paraíba, 2017. http://tede.bc.uepb.edu.br/tede/jspui/handle/tede/2740.
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This work aimed to estimate the general combining ability (GCA) and the specific combining ability (SCA) for agronomic traits among six upland cotton genotypes and their fifteen hybrid combinations; and to determine the predominant genetic effects in the control of the evaluated traits. In 2015, six cotton genotypes: FM 993, CNPA 04-2080, PSC 355, TAM B 139-17, IAC 26 and TAMCOT – CAMD-E, and fifteen hybrid combinations were evaluated at the Experimental Station of Embrapa Algodão, located in Patos - PB. The experiment consisted of a randomized block design with three replications. The following characteristics were evaluated: plant height (PH, cm); appearance of the first flower (AFF, days); appearance of the first boll (AFB, days); weight of one boll (BW, g); cotton seed yield (CSY, kg/ha); lint percentage (LP, %); cotton fiber yield (LY, kg/ha); length (LEN, mm); uniformity (UNI, %); strength (STR, gf/tex), and fineness (FIN, IM). Diallel analysis was carried out according to the method 2, model 1 of Griffing (1956). Significant differences were detected between the treatments and between the combining abilities estimates (GCA and SCA). Additive effects were predominant for the following characteristics: PH, AFF, AFB, LP, LEN, UNI, STR, FIN and non-additive effects were predominant for: BW, CSY and LY. The genotypes CNPA 04- 2080, IAC 26 and FM 993 showed highest estimates of gi for yield, and the genotype TAM B 139-17 presented the highest estimates for fiber characteristics. In general, the best combinations were: FM 993 x PSC 355, FM 993 x TAMCOT-CAMD-E, CNPA 04-2080 x TAM B 139-17, CNPA 04-2080 x TAMCOT-CAMD-E, PSC 355 x IAC 26 and TAM B 139- 17 x IAC 26, since they have the largest SCA (sij) with at least one of the parents of high GCA (gi). Therefore, they are indicated for extraction of elite lines and for the obtainment of superior genotypes.
O objetivo deste trabalho foi estimar a capacidade geral (CGC) e específica (CEC) de combinação para características agronômicas e tecnológicas de fibra entre seis genótipos de algodoeiro herbáceo e suas quinze combinações híbridas, bem como determinar os efeitos genéticos predominantes no controle dos caracteres avaliados. Em 2015, seis genótipos de algodoeiro: FM 993, CNPA 04-2080, PSC 355, TAM B 139-17, IAC 26 e TAMCOT – CAMD-E e quinze combinações híbridas foram avaliadas na Estação Experimental da Embrapa Algodão, localizada em Patos - PB. O delineamento utilizado foi o de blocos ao acaso com três repetições. Foram avaliadas as seguintes características: Altura de plantas (ALT, cm); Aparecimento da primeira flor (APF, dias); Aparecimento do primeiro capulho (APC, dias); Peso de um capulho (P1C, g); Produtividade de algodão em caroço (PROD, kg/ha); Porcentagem de fibras (PF, %); Produtividade de algodão em fibra (PRODF, kg/ha); Comprimento da fibra (COMP, mm); Uniformidade (UNF, %); Resistência (RES, gf/tex) e Finura (FIN, IM). Procedeu-se a análise dialélica, utilizando-se o método 2, modelo 1 segundo a metodologia proposta por Griffing (1956). Diferenças significativas foram detectadas entre os tratamentos e entre as capacidades combinatórias (CGC e CEC). Verificou-se predominância dos efeitos aditivos para as características: ALT, APF, APC, PF, COMP, UNF, RES, FIN e predominância dos efeitos não aditivos para: P1C, PROD e PRODF. Os genótipos CNPA 04-2080, IAC 26 e FM 993 apresentaram as maiores estimativas de gi para a produtividade, enquanto TAM B 139-17 obteve as maiores estimativas para as características de fibra. De um modo geral, as melhores combinações foram: FM 993 x PSC 355, FM 993 x TAMCOT-CAMD-E, CNPA 04-2080 x TAM B 139- 17, CNPA 04-2080 x TAMCOT-CAMD-E, PSC 355 x IAC 26 e TAM B 139-17 x IAC 26, por apresentarem as maiores CEC (Sij) com pelo menos um dos pais de alta CGC (gi ). Sendo assim, estas combinações são indicadas para extração de linhagens e obtenção de genótipos superiores.
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Ragsdale, Paul Irwin. "Diallel analysis of within-boll seed yield components and fiber properties in upland cotton (Gossypium hirsutum L.) and breeding potential for heat tolerance." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969/123.
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Coomer, Taylor Dayne. "Effect of Potassium Deficiency on Uptake and Partitioning in the Cotton (Gossypium hirsutum L.) Plant and Detection by a Crop Reflectance Sensor." Thesis, University of Arkansas, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10110014.
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For cotton (Gossypium hirsutum L.) to grow and develop normally, plants need to uptake the necessary amount of nutrients and use those nutrients in a beneficial fashion. It is recognized that cotton needs a certain tissue concentration of ions to achieve and maintain growth rates (Siddiqi et al., 1987). One of the most essential and abundant nutrients in cotton is potassium (K), second only by mass to nitrogen (N) (Marschner, 1995; Oosterhuis et al., 2013). Potassium exists in the soil in four separate pools and moves through soil to roots mainly through diffusion (Rengel & Damon, 2008; Samal et al., 2010; Ogaard et al., 2001). Potassium plays a vital role in plant growth and metabolism.
The objectives of this study were to determine the Michaelis-Menten parameters for the high-affinity transport system (HATS) and low-affinity transport system (LATS) uptake mechanisms of cotton, observe how K is partitioned throughout the cotton plant over a growing season with differing K fertilization rates, and to determine if cultivars differed in values from currently available indices formulated for N-status detection from active sensors. It also set out to determine if these N-sensitive indices were sensitive to leaf K concentration and available K2O in the soil, and to evaluate the role these indices play in predicting yield. It was hypothesized that a high K hydroponic environment would lead to more K uptake by cotton roots, which would lead to an increase in VMAX and KM. It was also hypothesized that with increased K fertilization, there would be greater K uptake and larger shift to reproductive components due to the plant having more than enough K in all other parts enabling it to send more to the reproductive components, and that greater K rates would lead to higher yields across all cultivars. It was believed that normalized difference vegetation index (NDVI) would more accurately predict leaf K, available K2O, and yield than normalized difference red edge (NDRE), that NDVI and NDRE would more accurately determine the K parameters chosen than canopy chlorophyll content index (CCCI), due to the strong influence of the red-edge band in the index and that yield would be most accurately predicted by the CCCI, due to yield being influenced by both chlorophyll content and biomass, and the CCCI involving the red-edge band to reflect chlorophyll content and the near infrared band to detect biomass.
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Dezordi, Cleci. "Desenvolvimento de meio de cultura semi-seletivo para detecção de Xanthomonas axonopodis pv. malvacearum em sementes de algodão (Gossypium hirsutum L.)." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-10082006-163250/.
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Um dos principais fatores limitantes da produção de algodão é a ocorrência de doenças e, entre os patógenos mais importantes estão às bactérias, que causam danos significativos à cultura. A doença conhecida como mancha angular, causada pela bactéria Xanthomonas axonopodis pv. malvacearum (Xam), é uma doença grave, que tem gerado grande preocupação dos produtores. Porém, muitos cultivares com boas características agronômicas apresentam suscetibilidade ao patógeno e, poucos são aqueles que apresentam resistência à doença. O controle da mancha angular é realizado basicamente com uso de resistência genética ao patógeno. Uma das principais fontes de inóculo para esta bactéria é a semente infectada. Este trabalho objetivou o desenvolvimento de um meio semi-seletivo para o isolamento de Xam em sementes de algodão, visando a utilização em análises de rotina em laboratórios de patologia de sementes. O meio de cultura semi-seletivo possuí a seguinte constituição: 3 g de extrato de carne; 5 g de peptona; 10 g de amido solúvel; 10 mL de Tween 80; 0,25 g de cloreto de cálcio; 150 µL de solução de cristal violeta a 1%; 50 mg de cefalexina; 10 mg de clorothalonil; 10 mg de tiofanato metílico e água destilada por 1000 mL. Este meio de cultura possui baixa repressividade a Xam e permite isolar este patógeno de sementes de algodão.One of the main limiting factors of the cotton production is the occurrence of diseases. The bacteria are among the most important pathogens causing significant losses in the production. Cotton bacterial blight is caused by the bacterium Xanthomonas axonopodis pv. malvacearum (Xam). Is a serious disease that affects cotton and has worried world producers. The main source of inoculum for this bacterium is the infected seed. This work had as objective the development of a semi-selective medium to detect Xanthomonas axonopodis pv malvacearum in cotton seeds for routine tests in seed pathology laboratories. By fungitoxicity tests, basead on qualitative and quantitative antibiograms, it was idealized a semi-selective medium with the folloing composition: peptone (5.0 g/L); agar (15.0 g/L); meat extract (3.0 g); starch (10.0 g/L); violet crystal (150.0 µL violet crystal solution at 1%); water (1,000 mL); CaCl2 (0.25 g); Tween 80 (10.0 mL/L). This medium has small effect on Xam and allows to isolate cotton seeds pathogens.
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Reeves, Richard Bernard. "Spatial-temporal variation of the density and distribution of stink bugs (Heteroptera: Pentatomidae) in cotton, Gossypium hirsutum (L.), as part of a diverse agroecosystem." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1252937903/.
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Navarro-Ainza, Jose A. Cristobal. "Fertilizer Nitrogen Recovery and N15 and Bromide Distribution in the Soil Profile as Affected by the Time of Application on an Irrigated Upland Cotton (Gossypium hirsutum L.)." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194172.
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The first project involved the evaluation of different times of application on the fertilizer nitrogen recovery (FNR) in the soil-plant system in an irrigated upland cotton system, during two seasons. This was accomplished by using the isotopic dilution technique applying the 15N to microplots. No differences were observed in the total plant FNR, seed and stover, soil and the total FNR among the different 15N application times; however, despite no differences were observed in the plant the FNR value ranged from 30-38%, while the seed exhibited the highest FNR with an average over 50% of the 15N recovered in the plant. In the soil, the obtained average FNR value was over 40% while the total FNR (plant + soil) ranged from 70-80%, being reduced as the 15N application time was delayed.The second project was conducted during two seasons to examine the 15N and bromide distribution pattern in the soil profile as a function of the time of application. 15Nitrogen and bromide were applied to the soil at three different times in a cotton growth cycle; after that, soil samples were taken at the end of the cotton cycle to a depth of 1.80 m., and 15N and bromide recoveries were determined. Slightly higher FNR were obtained with the intermediate application time. The higher FNR were detected in the surface layer (0-30 cm) with an average of 40%. Below 30 cm depth, low 15N recoveries were obtained and even lower below the 60 cm soil layer. Bromide recovery behavior was related to the water movement in the soil profile: as the Br- application time was delayed more of the anionic tracer was found in the top of the soil profile, while less Br- was found in the surface soil for the early Br- application time.
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Huynh, Tu T. "Palmitoyl-acyl Carrier Protein Thioesterase in Cotton (Gossypium hirsutum L.): Biochemical and Molecular Characterization of a Major Mechanism for the Regulation of Palmitic Acid Content." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc2891/.
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The relatively high level of palmitic acid (22 mol%) in cottonseeds may be due in part to the activity of a palmitoyl-acyl carrier protein (ACP) thioesterase (PATE). In embryo extracts, PATE activity was highest at the maximum rate of reserve accumulation (oil and protein). The cotton FatB mRNA transcript abundance also peaked during this developmental stage, paralleling the profiles of PATE enzyme activity and seed oil accumulation. A cotton FatB cDNA clone was isolated by screening a cDNA library with a heterologous Arabidopsis FatB probe (Pirtle et al., 1999, Plant and Cell
Physiology 40: 155-163). The predicted amino acid sequence of the cotton PATE preprotein had 63% identity to the Arabidopsis FatB thioesterase sequence, suggesting that the cotton cDNA clone probably encoded a FatB-type thioesterase. When acyl-CoA synthetase-minus E. coli mutants expressed the cotton cDNA, an increase in 16:0 free fatty acid content was measured in the culture medium. In addition, acyl-ACP thioesterase activity assays in E. coli lysates revealed that there was a preference for palmitoyl-ACP over oleoyl-ACP in vitro, indicating that the cotton putative FatB cDNA encoded a functional thioesterase with a preference for saturated acyl-ACPs over unsaturated acyl-ACPs (FatA). Overexpression of the FatB cDNA in transgenic cotton resulted in elevated levels of palmitic acid in transgenic somatic embryos compared to control embryos. Expression of the anti-sense FatB cDNA in transgenic cotton plants produced some plants with a dwarf phenotype. These plants had significantly smaller mature leaves, all with smaller cells, suggesting that these plants may have less palmitic acid available for incorporation into extraplastidial membrane lipids during cell expansion. Thus manipulation of FatB expression in cotton directly influenced palmitic acid levels. Collectively, data presented in this dissertation support the hypothesis that there indeed is a palmitoyl-ACP thioesterase in cotton, encoded by the isolated FatB cDNA, which plays a major role in regulating palmitic acid content of extraplastidial complex glycerolipids. This work forms the basis for future studies of the influence of palmitic acid content on plant membrane function and provides a key target for the metabolic engineering of palmitic acid levels in storage oils of developing cottonseeds.
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Inácio, Estela Maris. "Impactos da deriva do herbicida 2,4-D em culturas sensíveis." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-30092016-105412/.
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O herbicida 2,4-D é utilizado principalmente para o controle de plantas daninhas em condições de pós-emergência em culturas em que o herbicida é seletivo, bem como no manejo da vegetação em pré-plantio; no entanto, devido a suas características físico-químicas, pode ocasionar danos às culturas vizinhas sensíveis, através dos fenômenos de deriva da molécula durante as pulverizações. Sendo assim, é de fundamental importância o conhecimento técnico dos impactos causados pela deriva do herbicida 2,4-D em culturas sensíveis. No entanto, as informações existentes na literatura para dar suporte às possíveis liberações futuras de culturas resistentes a este herbicida são escassas. Os experimentos foram conduzidos em casa-de-vegetação e laboratório da Escola Superior de Agricultura \"Luiz de Queiroz\" - Universidade de São Paulo - ESALQ/USP. Os objetivos da presente pesquisa foram: (i) avaliar a influência do herbicida 2,4-D no desenvolvimento das culturas do algodão e soja em, diferentes estádios fenológicos, (ii) avaliar os possíveis danos causados pela deriva do herbicida 2,4-D no crescimento e desenvolvimento das culturas de algodão e soja, em diferentes estádios fenológicos, e (iii) observar através da microscopia eletrônica de varredura possíveis alterações nas estruturas foliares das plantas de algodão e soja após o contato com o herbicida. Curvas de doseresposta foram obtidas a partir de experimentos conduzidos em casa-de-vegetação. Para isso, foram conduzidos dois ensaios, sendo os tratamentos com o herbicida aplicado quando as plantas atingiram os estágios fenológicos: V2 (segundo nó vegetativo); R1 (início da floração para a cultura de soja), F1 (início da floração da cultura de algodão); e R6 (vagens da soja com enchimento pleno e folhas verdes) e C1 (algodão no final do florescimento efetivo e frutificação plena). No primeiro experimento os tratamentos utilizados foram: 0D (testemunha), 0,25D, 0,5D, 1D, 2D e 4D, sendo D a dose recomendada do 2,4-D, e no segundo experimento as doses utilizadas foram: 0D, 1D, 0,1D, 0,01D, 0,001D, 0,0001D. Utilizando as mesmas plantas da primeira etapa da pesquisa foram feitas amostragens das folhas para a caracterização foliar através de microscopia eletrônica de varredura. O 2,4-D comprometeu significativamente o crescimento e desenvolvimento das plantas de soja em todos os estádios fenológicos, com fitotoxicidade superiores a 65%. Resultados semelhantes foram obtidos na cultura do algodão, onde o menor nível de dano foi de 42,5% relativa à aplicação do herbicida no estádio fenológico R6 na dose de 0,25D. Observando os tratamentos nas subdoses do herbicida, na soja, verificou se que a maior porcentagem de fitotoxicidade foi obtida na dose de 0,1D, em todos os estádios fenológicos, os níveis de dano foram superiores a 50% na última avaliação. Em relação à cultura do algodão resultados semelhantes foram obtidos, com exceção do estádio fenológico R6, quando todos os estádios apresentaram porcentagem de fitotoxicidade superior a 40%. Em relação às características foliares do algodão e soja após aplicações de 2,4-D através da análise das características foliares em microscópio eletrônico de varredura, após a aplicação do herbicida, observou-se que o produto promoveu alterações nas estruturas foliares de algodão e soja em todas as doses estudadas.The herbicide 2,4-D is used to control weeds in post-emergence conditions in crops which it is selective, as well in pre-planting vegetation management, however, due to its physical-chemical characteristics it may cause damage to susceptible neighbor crops, by the drift of the molecule during the spray. Therefore, it is of fundamental importance the technical knowledge of the impacts caused by the drift of the molecule during the application. The experiments were conducted in greenhouse and in the laboratory of the College of Agriculture \"Luiz de Queiroz\". So the objectives of this study were (i) to evaluate the possible damage caused by 2,4-D in the initial development of cotton and soybean crops (ii) to evaluate the possible damage caused by 2,4-D drift in the initial development of cotton and soybean crops and (iii) to observe by electron microscopy scanning possible changes in leaf structure of plants cotton and soybeans after contact with the herbicide. Dose-response curves were obtained from experiments conducted in the greenhouse. For that, it was conducted two trials, being the treatments with the herbicide sprayed when the plants reached the following phenological stages: V2 (second vegetative node); R1 (beginning of flowering for soybeans) and F1 (beginning of flowering in cotton); and R6 (soybean pods with full filling and green leaves) and C1 (cotton at the end of effective flowering and fruiting full). In the first experiment the doses were related to the effect of doses (0D, 0.25D, 0.5D, 1D, 2D, 4D), where D is the recommended dose of the herbicide 2,4-D, and in the second experiment evaluated the effect of underdoses (0D, 1D, 0.1D, 0.01D, 0.001D and 0.0001D). Using the same plants of the first and second step of the research it was sampled leaves for the foliar characterization by scanning electron microscopy. The 2,4-D affected significantly the growth and development of the soybean plants in all phenological stages, with phytotoxicity superior to 65%. Similar results were obtained in cotton, where the lower level of damage was 42.5% on the application of the herbicide on growth stage R6 with the 0.25D dose. Regarding to the application of doses of the herbicide 2,4-D on soybeans, it was observed that the highest percentage of phytotoxicity to the crop was at the dose of 0.1D; in all growth stages the damage levels were above 50% in the last evaluation. Regarding to the cotton crop, similar results were obtained, except for the R6 growth stage, every stage showed higher percentage of phytotoxicity than 40%. Regarding to the characteristics of the cotton and soybean leaves following 2,4-D application, it was found that the product caused alterations in leaf structure of the plants in all doses.
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Cottee, Nicola Sandra. "Thermotolerance of cotton." University of Sydney, 2009. http://hdl.handle.net/2123/5428.
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Doctor of Philosophy (PhD)The Australian cotton industry has developed high yielding and high quality fibre production systems and attributes a significant contribution of this achievement to highly innovative breeding programs, specifically focused on the production of premium quality lint for the export market. Breeding programs have recently shifted attention to the development of new germplasm with superior stress tolerance to minimise yield losses attributed to adverse environmental conditions and inputs such as irrigation, fertilisers and pesticides. Various contributors to yield, such as physiology, biochemistry and gene expression have been implemented as screening tools for tolerance to high temperatures under growth cabinet and laboratory conditions but there has been little extension of these mechanisms to field based systems. This study evaluates tools for the identification of specific genotypic thermotolerance under field conditions using a multi-level ‘top down’ approach from crop to gene level. Field experiments were conducted in seasons 1 (2006) and 3 (2007) at Narrabri (Australia) and season 2 (2006) in Texas (The United States of America) and were supplemented by growth cabinet experiments to quantify cultivar differences in yield, physiology, biochemical function and gene expression under high temperatures. Whole plants were subjected to high temperatures in the field through the construction of Solarweave® tents and in the growth cabinet at a temperature of 42 oC. The effectiveness of these methods was then evaluated to establish a rapid and reliable screening tool for genotype specific thermotolerance that could potentially improve the efficiency of breeding programs and aid the development to high yielding cultivars for hot growing regions. Cotton cultivars Sicot 53 and Sicala 45 were evaluated for thermotolerance using crop level measurements (yield and fibre quality) and whole plant measurements (fruit retention) to determine the efficacy of these measurements as screening tools for thermotolerance under field conditions. Sicot 53 was selected as a relatively thermotolerant cultivar whereas Sicala 45 was selected as a cultivar with a lower relative thermotolerance and this assumption was made on the basis of yield in hot and cool environments under the CSIRO Australian cotton breeding program. Yield and fruit retention were lower under tents compared with ambient conditions in all 3 seasons. Yield and fruit retention were highly correlated in season 1 and were higher for Sicot 53 compared to Sicala 45 suggesting that fruit retention is a primary limitation to yield in a hot season. Thus yield and fruit retention are good indicators of thermotolerance in a hot season. Temperature treatment and cultivar differences were determined for fibre quality in seasons 1 and 3; however, quality exceeded the industry minimum thereby indicating that fibre quality is not a good determinant of thermotolerance. Physiological determinants of plant functionality such as photosynthesis, electron transport rate, stomatal conductance and transpiration rate were determined for cultivars Sicot 53 and Sicala 45 under the tents and an index of these parameters was also analysed to determine overall plant physiological capacity in the field. Physiological capacity was also determined under high temperatures in the growth cabinet using a light response curve at various levels of photosynthetically active radiation (PAR). Photosynthesis and electron transport rate decreased, whilst stomatal conductance and transpiration rate increased under the tents as well as under high temperatures in the growth cabinet. Photosynthesis and electron transport rate were higher for Sicot 53 but stomatal conductance and transpiration rate were higher for Sicala 45 under the tents. No cultivar differentiation was evident for plants grown under high temperatures in the growth cabinet. Temperature treatment and cultivar differences in physiological function were greater in a hot year (season 1), thereby indicating the importance of cultivar selection for thermotolerance in the presence of stress. Electron transport rate was correlated with yield in season 1, thus suggesting the suitability of this method for broad genotypic screening for thermotolerance under field conditions. Biochemical processes such as membrane integrity and enzyme viability were used to determine cultivar specific thermotolerance under high temperature stress in the laboratory, field and growth cabinet. Electrolyte leakage is an indicator of decreased membrane integrity and may be estimated by the relative electrical conductivity or relative cellular injury assays. The heat sensitivity of dehydrogenase activity, a proxy for cytochrome functionality and capacity for mitochondrial electron transport, may be quantified spectrophotometrically. Cellular membrane integrity and enzyme viability decreased sigmoidally with exposure to increasing temperatures in a water bath. Membrane integrity was higher for Sicot 53 compared with Sicala 45 under the tents and under high temperatures in the growth cabinet. No temperature treatment or cultivar differences were found for enzyme viability under the tents; however, enzyme viability for Sicala 45 was higher in the growth cabinet compared with Sicot 53. Relative electrical conductivity was strongly correlated with yield under ambient field conditions and under the tents, suggesting impairment of electron flow through photosynthetic and/or respiratory pathways, thus contributing to lower potential for ATP production and energy generation for yield contribution. Thus, the membrane integrity assay was considered to be a rapid and reliable tool for thermotolerance screening in cotton cultivars. Gene expression was examined for cultivars Sicot 53 and Sicala 45 grown under high (42 oC) temperatures in the growth cabinet. Rubisco activase expression was quantified using quantitative real-time polymerase chain reaction analysis and was decreased under high temperatures and was lower for Sicala 45 than Sicot 53. Maximum cultivar differentiation was found after 1.0 h exposure to high temperatures and hence, leaf tissue sampled from this time point was further analysed for global gene profiling using cDNA microarrays. Genes involved in metabolism, heat shock protein generation, electron flow and ATP generation were down-regulated under high temperatures in the growth cabinet and a greater number of genes were differentially expressed for Sicala 45, thereby indicating a higher level of heat stress and a greater requirement for mobilisation of protective and compensatory mechanisms compared with Sicot 53. Cultivar specific thermotolerance determination using gene profiling may be a useful tool for understanding the underlying basis of physiological and biochemical responses to high temperature stress in the growth cabinet. There is future opportunity for profiling genes associated with heat stress and heat tolerance for identification of key genes associated with superior cultivar performance under high temperature stress and characterisation of these genes under field conditions. This research has identified cultivar differences in yield under field conditions and has identified multiple physiological and biochemical pathways that may contribute to these differences. Future characterisation of genes associated with heat stress and heat tolerance under growth cabinet conditions may be extended to field conditions, thus providing the underlying basis of the response of cotton to high temperature stress. Electron transport rate and relative electrical conductivity were found to be rapid and reliable determinants of cultivar specific thermotolerance and hence may be extended to broad-spectrum screening of a range of cotton cultivars and species and under a range of abiotic stress. This will enable the identification of superior cotton cultivars for incorporation into local breeding programs for Australian and American cotton production systems.
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Singh, Shilpy. "Characterization of the activity of fluazifop-butyl on bristly starbur (Acanthospermum hispidum DC.) and trimethylsulfonium salt of glyphosate on Round-up Ready cotton (Gossypium hirsutum L.)." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010831.
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O'Berry, Nathan Brook. "Individual Experiments to Evaluate the Effects of Plant Population and Planting Date, Cultivar and Plant Growth Regulator Application, and Herbicide and Plant Growth Regulator Application on Cotton (Gossypium hirsutum L.) Growth and Development, Yield, and Fiber Quality." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33882.
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Cotton (Gossypium hirsutum L.) growth and development, lint yield, and fiber quality are influenced by many management decisions. Three field experiments examining the interaction of plant population and planting date, and cultivar or herbicide and plant growth regulator application on these parameters were conducted in Virginia during 2005 and 2006 and in North Carolina, South Carolina, and Louisiana during specific years.
Experiment I: Plant Population and Planting Date
Lint yields were highest with populations of 8.9 and 12.8 plants m¯² compared to 5.3 plants m¯² in Virginia and North Carolina, while in Louisiana the highest yields resulted from populations of 5.8 and 9.5 plants m¯² compared to 17.1 plants m¯². Earlier planted (1 May) cotton produced higher yields relative to later planted (21 May) cotton in Louisiana, while yield was not influenced by planting date in Virginia and North Carolina. The impact of plant population and planting date on cotton appeared to be influenced significantly by heat unit accumulation.
Experiment II: Cultivar and Mepiquat Pentaborate Application
Mepiquat pentaborate (MPB) application consistently decreased plant height, HNR, and enhanced maturity for all cultivars, compared to untreated cotton. A trend of decreasing yield with increasing MPB application in Virginia was observed. These data suggests that cotton response to MPB application is influenced by cultivar maturity or fruiting interval.
Experiment III: Trifloxysulfuron-sodium and Mepiquat Chloride Application
Trifloxysulfuron-sodium (TFS) did not influence vegetative growth, maturity, or yield in comparison to untreated cotton. Mepiquat chloride (MC) application reduced vegetative growth and enhanced maturity in most years. The results of this experiment demonstrate that TFS application does not have the same effects on plant growth as MC application.Master of Science
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SOUSA, Eric Beserra de Melo. "Indicadores fisioquímicos para seleção de plantas de algodão herbáceo tolerantes à seca." Universidade Federal Rural de Pernambuco, 2008. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4785.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The cotton culture performs a relevant economical-social importance in Brazil and the entire world, being placed among the ten larger wealth sources in the Brazilian agricultural section. Brazil faces long periods of water shortage in most of the arable areas. Thus, evaluation about water deficit in this culture is necessary. This work was performed in order to evaluate the effect of water stress on growth and water relations of three cotton cultivars (Gossypium hirsutum L.) in greenhouse conditions. An experiment was carried out in a 3 x 4 factorial arrangement with three cotton cultivars (7MH, CEDRO and 7H) and four water levels: 25, 50,75 and 100% of field capacity, with five replicates. The height, stem diameter and number of leaves were analyzed. At the end of the experimental period, dry matter of the leaves, stem, roots, root to shoot ratio and biomass allocation were determined and the leaf area was calculated. About the water relations, the parameters analyzed were: transpiration (E), diffusive resistance (rs), pre-dawn and noon leaf water potential (Yw), relative water content (RWC), and soluble carbohydrates, soluble proteins and free proline contents. These analyses were performed in three times (15, 30 and 40 days after differentiation). Water stress reduced the height, number of leaves, stem diameter, and leaf area in all cultivars. Water deficit reduced leaf, stem, and root dry matter. On the hardest treatments, biomass allocation to leaves and roots increased to all cultivars. Root to shoot ratio increased too on the threecultivars in the hardest treatments. At the end of the experimental period, transpiration was elevated in the plants under 25% FC and diffusive resistance was reduced in the three cultivars. The opposite was observed in the plants with good water availability, exception on the cv. CEDRO. Water deficit reduces the leaf water potential in the two evaluation times and the RWC. In general, the three cultivars under severe stress accumulated soluble carbohydrates, free proline and soluble proteins. Evaluating the growth and water relations, the results suggest that cv. 7MH is more adapted to drought, being followed to cv. CEDRO.
A cultura do algodoeiro apresenta relevante importância econômico-social no Brasil e no mundo, estando situada dentre as dez maiores fontes de riqueza no setor agropecuário brasileiro. Dessa forma, fazem-se necessários estudos que avaliem essa cultura em situações de déficit hídrico, visto que a maioria das áreas cultiváveis no Brasil passa por longos períodos de escassez hídrica. Assim, objetivou-se avaliar o efeito do déficit hídrico em variáveis de crescimento e nas relações hídricas de três cultivares de algodoeiro herbáceo (Gossypium hirsutum L.), em casa de vegetação. O delineamento experimental foi inteiramente casualizado em esquema fatorial 3 x 4, representado por três cultivares (7MH, CEDRO e 7H) e quatro níveis de água: 25, 50, 75 e 100% da capacidade de pote com 5 repetições. A cada sete dias, foram mensuradas a altura da planta, número de folhas e diâmetro do caule. Também foram mensuradas a transpiração, resistência difusiva, potencial hídrico foliar ( f) pre-dawn e ao meio dia, teor relativo de água (TRA) e as concentrações de carboidratos e proteínas solúveis e prolina livre. Estes últimos avaliados com 15, 30 e 45 dias após a diferenciação (DAD). Ao final do período experimental foi calculada a área foliar e a concentração dos solutos orgânicos para a raiz. As plantas tiveram seus órgãos separados e levados à estufa para a obtenção da matéria seca das folhas, caule e raízes. Com isso calculousea alocação de biomassa para as folhas, caules, raízes e a relação raiz/parte aérea (R/Pa). O estresse hídrico aplicado provocou reduções significativas na altura da planta, número de folhas, diâmetro do caule, área foliar e na produção de matéria seca nas três cultivares estudadas. Houve aumento na alocação de biomassa da folha e da raiz. Também houve aumento na relação raiz/parte aérea nas três cultivares nos tratamentos mais severos. Com o prolongamento do estresse, a transpiração aumentou nas plantas sob tratamento severo (25% da CP) e conseqüentemente reduziu a resistência difusiva nas três cultivares estudadas. O inverso foi observado para as plantas com bom suprimento hídrico, com exceção da cv.CEDRO. O déficit hídrico reduziu o potencial hídrico foliar nos dois horários de avaliação e o TRA. De forma geral, houve acúmulo nos teores de carboidratos solúveis, prolina livre e proteínas solúveis para as três cultivares nas plantas sob estresse severo. Com esses resultados pode-se sugerir que a cv. 7MH é a mais recomendada para ser cultivada em locais com restrições hídricas, seguida da cv. CEDRO, enquanto que a cv. 7H mostrou-se mais sensível.
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Crow, Whitney Desiree. "The Compounding Stresses of Tobacco Thrips, Frankliniella fusca (Hinds), and Reniform Nematode, Rotylenchulus reniformis (Linford & Oliveira), on the Growth and Development of Cotton, Gossypium hirsutum L." Thesis, Mississippi State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10752036.
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The objectives of this research were to evaluate management options for tobacco thrips, Frankliniella fusca (Hinds), and reniform nematode, Rotylenchulus reniformis (Linford & Oliverira), in cotton productions systems. When evaluating tillage practices for pest control, conservational tillage reduced thrips densities and damage, while the impact on nematode densities is less understood and in this study had no impact. Insecticide seed treatments remain a vital resource for controlling thrips in Mid-South cotton production systems. When incorporating an early season herbicide application for weed control, systems with an insecticide seed treatment generally tolerated herbicide injury better than those with early season stress from thrips and nematodes. When using foliar applications as an alternative option for thrips management, early season automatic applications at the cotyledon stage followed by one or two sequential applications provided similar efficacy to the insecticide seed treatment. For reniform nematode management, 1, 3-dichloropropene reduced densities lower than that of the untreated control or aldicarb; however, depending on environmental conditions this practice may not result in yield increases great enough to warrant the cost of application. These data highlight the importance of effective control of thrips whether it be via at-planting or foliar applications. 1, 3-dichloropropene reduced nematode densities and is an effective option in nematode management; however, nematodes are a stress pathogen and the ability to minimize other seasonal stresses ,such as water stress, will determine if a nematicide application may be needed. While environmental conditions may be optimal to allow for plant recoverability, effective early season pest management decreases the potential for delayed crop maturity which could lead to increased input cost or reduced yield later in the season.
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Cardoso, Gleibson Dionízio [UNESP]. "Períodos de interferência de plantas daninhas em algodoeiro cultivares BRS Safira e BRS Verde." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/105229.
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Este trabalho teve como objetivo identificar os períodos de interferência das plantas daninhas no algodoeiro de fibra naturalmente colorida (BRS Safira e BRS Verde), e avaliar o efeito da competição das plantas daninhas na produtividade desta cultura. Dois experimentos foram instalados na área experimental da Embrapa Algodão em Missão Velha, CE, (7º42’07’’ de latitude e 39º24’18’’ de longitude, altitude de 360 m) na safra 2007/2008, utilizando-se o espaçamento de 1,00 x 0,20 m. Utilizou-se o delineamento experimental em blocos ao acaso, com quatro repetições, os tratamentos constaram de duas: modalidades de competição (convivência e controle de plantas daninhas) e períodos de interferência das plantas daninhas. Os períodos iniciais de controle ou de convivência após a emergência da cultura foram 0-20, 0-40, 0-60, 0-80 dias após a emergência (DAE) e 0-colheita (120 dias). Para determinação dos períodos de interferência, considerando-se perdas na produtividade de 2, 5 e 10%; foi realizada análise de regressão do modelo sigmoidal de Boltzmann, utilizando-se os dados de produtividade separadamente dentro de cada modalidade de competição. A comunidade infestante para ambas cultivares, foi composta por 21 espécies, destacando-se: Richardia grandiflora, Amaranthus deflexus, Eleusine indica, Merremia aegyptia, Eragrotis pilosa, Cenchrus echinatus e Waltheria indica. Observou-se para cultivar BRS Safira, que os períodos anteriores a interferência (PAI) foram, respectivamente, 8, 14 e 20 DAE, para perdas na produtividade de 2, 5 e 10%; e os períodos críticos de prevenção a interferências (PCPI), para esses mesmo níveis de perdas, foram respectivamente, 100, 82 e 60 dias. Para cultivar BRS Verde, os PAIs foram, respectivamente, 25, 31 e 35 DAE, para perdas de 2, 5 e 10%; e os PCPIs, para esses mesmo níveis de perdas, foram respectivamente...
This study aimed to determine the late-season presence of weeds in reddish brown cotton and green cotton (cultivars BRS Safira and BRS Verde) and the critical times for removing weeds. And assess the effect of weeds competition in the crop productivity. Two experiments were carried out in the area of Embrapa in Missão Mission-CE, Brazil, the region Cariri, located at 7º42’07’’ S latitude and 39º24’18’’ WGr. longitude, altitude of 360 m, in the 2007/2008 season. The treatments consisted of two control groups: weed-free crop during the initial period after crop emergency, and crop kept with weeds during initial period after plant emergency. Both consisted, 0, 20, 40, 60, 80 e 120 days after crop emergency (DAE). Regression analysis was performed of the model of sigmoidal Boltzmann, using data from productivity separately within each type of competition, to identify the critical periods of competition considering 2, 5 and 10% reduction in yield. The community of weeds, for both cultivars, was composed by 21 predominant species, standing out among them: Richardia grandiflora, Amaranthus deflexus, Eleusine indica, Merremia aegyptia, Eragrotis pilosa, Cenchrus echinatus and Waltheria indica. For cultivar BRS Safira, considering 2, 5 and 10% reduction in yield fiber as acceptable, the period preceding the interference was, respectively, 8, 14 and 20 (DAE). And the critical periods of prevention to interferences, for those same levels of losses, they were respectively, 100, 82 and 60 (DAE). For cultivar BRS Verde, considering 2, 5 and 10% reduction in yield fiber as acceptable, the period preceding the interference was, respectively, 25, 31 and 35 (DAE). And the critical periods of prevention to interferences, for those same levels of losses, they were respectively, 67, 43 and 22 (DAE). The BRS Safira cultivar was more susceptible to interference of the weed community that BRS Verde.
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Flach, Leonir. "Qualidade fisiológica de sementes de algodão tratadas quimicamente e armazenadas em condição ambiente." Universidade Federal de Pelotas, 2015. http://repositorio.ufpel.edu.br:8080/handle/prefix/3292.
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Considerando a importância do tratamento e da manutenção da qualidade da semente durante o armazenamento, objetivou-se através deste trabalho avaliar o desempenho fisiológico de sementes de algodão tratadas quimicamente e armazenadas em condição ambiente. O delineamento experimental foi inteiramente casualizado, com 6 repetições, em esquema fatorial 9 x 6 (tratamentos x época de avaliação). Foram realizados os seguintes tratamentos de sementes: T1 – Testemunha (sem tratamento); T2 – Fungicida Carbendazin 150g/l e Tiran 350g/l (600 ml/100 kg de sementes); T3 – Fungicida Triadmenol 150g/l (200 ml/100 kg de sementes); T4 – Fungicida Pencicurom 250g/l (300 ml/100 kg de sementes); T5 – Fungicida Azoxistrobina 75g/l, Metalaxil-M 37,5g/l e Fludioxonil 12,5 g/l (300 ml/100kg de sementes); T6 – Inseticida Imidacloprido 150 g/l e Tiodicarbe 450g/l (2400 ml/100kg de sementes); T7 – Inseticida Tiametoxam 350g/L (600ml/100kg de sementes); T8 – Composto pelos tratamentos 2, 3, 4 e 6 mencionados acima; T9 – Composto pelos tratamentos 5 e 7. A avaliação da qualidade fisiológica das sementes de algodão foi realizada aos 0, 30, 60, 90, 120 e 150 dias de armazenamento através dos testes de germinação e vigor (baixa temperatura e envelhecimento acelerado). Os resultados permitem constatar que os produtos (triadmenol) e o (carbendazin e tiran + triadmenol + Pencicurom + imidacloprido e tiodicarbe) reduzem os percentuais de germinação e vigor da sementes de algodão. A qualidade fisiológica é negativamente afetada conforme se aumenta o período de armazenamento.
Considering the importance of treatment and maintenance of seed quality during storage, the aim through this work was to evaluate the physiological performance of cotton seeds chemically treated and stored at room temperature. The experimental design was completely randomized with six replications in factorial scheme 9 x 6 (treatments x evaluation time). The following seed treatments were used: T1 - control (no treatment); T2 - Fungicide Carbendazin 150g / l Tiran 350g / l (600 ml / 100 kg seed); T3 - Fungicide Triadmenol 150g / l (200 ml / 100 kg seed); T4 - Fungicide Pencicurom 250g / l (300 ml / 100 kg seed); T5 - Fungicide Azoxystrobin 75g / l, Metalaxyl-M 37,5g / l Fludioxonil 12.5 g / l (300 ml / 100kg seed); T6 - insecticide Imidacloprid 150 g / l Thiodicarb 450g / l (2400 ml / 100kg seed); T7 - insecticide thiamethoxam 350 g / L (600ml / 100kg of seeds); T8 - for treatments compound 2, 3, 4 and 6 mentioned above; T9 - Composed by treatments 5 and 7. The evaluation of the physiological quality of cotton seeds was performed at 0, 30, 60, 90, 120 and 150 days of storage through the germination and vigor tests (low temperature and accelerated aging). The results help determine that the product (triadmenol) and (carbendazin and tyranny + triadmenol + Pencicurom + imidacloprid and thiodicarb) reduce the percentage of germination and vigor of cotton seeds. The physiological quality is adversely affected as increases the storage period.
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(9826022), Lance Pendergast. "Benefits of aeration of subsurface drip irrigation water: Field evidence on CQ highlands vertosols." Thesis, 2011. https://figshare.com/articles/thesis/Benefits_of_aeration_of_subsurface_drip_irrigation_water_Field_evidence_on_CQ_highlands_vertosols/13463510.
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Irrigation of heavy soils can result in temporary anoxic conditions in the rhizosphere. The aeration of the subsurface drip irrigation water was calculated to deliver an amount of oxygen that is significant to root respiration (equivalent to some hours of respiration need). Broadacre cotton (Gossypium hirsutum L.) irrigated with aerated water developed significantly more extensive and heavier (17.3%) root systems, canopies that enabled greater light interception (2.6% ), and produced significantly higher lint yields ( 16%) due to more bolls per plant (15%) in the 05/06 season. The increased yields of aerated plants were associated with improved gross production water use index (GPWUI), irrigation water use index (IWUI) and crop water use index (CWUI) by 16.9, 16.8 and 15.5% respectively. These improvements in yields and water use efficiencies in response to aeration were ascribed to enhanced root development and performance. Although trends were similar across two seasons, the differences were not significantly different in the first (04/05) season, a result attributed to inadequate replication in the trials of that year. A chickpea ( Cicer arietinum L.) crop grown in rotation to cotton produced significantly higher yields (26.9%; 359 vs. 283 g m-2), IWUI (27%, 2400 vs. 1890 g m-3) and GPWUI (26.8%; 1750 vs. 1380 g m-3) under aerated SDI, compared to nonaerated SDI. The aeration effect was more pronounced when drippers were placed at depth (25 and 35 em, compared to 5 and 15 em) (chickpea pot experiment). Aerated chickpea irrigated at the deepest emitter depth produced significantly higher yields (by 1 0.9%) and GPWUI (21 %) than their non-aerated counterparts. A field sorghum (Sorghum bicolor L.) crop grown following the second chickpea crop did not respond to the aeration treatment in terms of yield or water use efficiency (WUE), a result attributable to either the effect of a relatively wet season where the contribution of irrigation to total water use was less than 50%, or to a relative insensitivity of sorghum to soil anoxia. Aeration of SDI water improved cotton plant growth (larger root systems, heavier above-ground biomass and higher yield) for irrigation water with an electrical conductivity of0.78 dSm-1, but not at higher levels. The ratios of cotton leaf K+:Na+, Ca2+:Na+ and Mg2+:Na+ were increased (by 45.7%, 31.7% and 34.9%, respectively) by the aeration treatment, compared to the control, suggesting a higher level of salt exclusion by the root in the aerated treatments. This result is interpreted as due to maintenance of membrane integrity under aerobic conditions. Aeration of SDI has the potential to make a major contribution to sustainable water use for irrigated agriculture on heavy soils. The benefits of aeration of SDI in terms of both crop yield and water use efficiency improve the economic feasibility of this irrigation method.
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Gardner, Andrew Perry. "Weed management in glufosinate-tolerant cotton (Gossypium hirsutum L.)." 2006. http://www.lib.ncsu.edu/theses/available/etd-03162006-200356/unrestricted/etd.pdf.
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Dewi, Elvira Sari. "Root Morphology of Drought Resistance in Cotton (Gossypium hirsutum L.)." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7373.
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A combination of root morphology and plant physiology with drought/or salt tolerance should affect drought resistance in cotton (Gossypium hirsutum L.). This experiment was developed to evaluate early vegetative and seedling growth of cotton from the unselected parents with two selected populations of M-8844-0100, DPL 50, and TAM 94L-25 across two cycles for seedling drought. Three genotypes from three generations of selection were grown in tubes to evaluate early growth and in containers to evaluate seedlings for drought resistance in a greenhouse at College Station, TX in 2008 and 2009. The experiment during the winter months of 2008 resulted in shorter tap root length, fewer lateral roots, and lower fresh and dry weight for total root, lateral roots, and shoots. The drought selections in these genotypes affected the tap root fresh weight, and the number and weight of lateral roots. TAM 94L-25 averaged higher tap root fresh and dry weight, lateral root fresh weight and shoot fresh weight. DPL 50 exhibited greater weight of lateral roots and shoot fresh weight. No difference was found in percent wilting across generations for drought at 75 percent apparent wilting and recovery at 90 percent apparent wilting.
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Dumka, Disha. "Efficacy of delayed fruiting in improving drought tolerance of cotton (Gossypium hirsutum. L.) In Georgia." 2002. http://purl.galileo.usg.edu/uga%5Fetd/dumka%5Fdisha%5F200205%5Fms.
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Berger, Gregory L. "Diallel analysis and heritability estimates of fiber traits for ELS, Gossypium hirsutum L., progeny." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-280.
Full textAbstract:
With a demand for high-quality cotton fiber in international markets,
improvement of fiber quality in U.S. grown commercial cultivars is necessary. Smith,
Hague, Thaxton, and Jones developed a group of experimental lines in 2008 that
produced extra-long staple fiber (>35.6 mm). This study determined general combining
ability (GCA), and specific combining ability (SCA) of four experimental ELS lines and
four commercial cultivars utilizing biplot and conventional diallel analysis, determined
performance of F2 progeny, calculated broad-sense (H2) heritability estimates for F2
progeny, and verified the ability of selected parental combinations to produce variable
segregating populations with variability of fiber traits. Initial crosses were made in 2007,
with additional crosses being made in the field and in a greenhouse in 2008. F1 progeny
and parents were grown in a replicated trial near College Station, TX, in 2007 and 2008.
F2 progeny lines and parents were grown in replicated trials at two locations in 2008.
Due to a significant GxY interaction for all F1 fiber traits, data were reported by years.
Experimental ELS lines showed positive GCA effects for fiber length, strength, and length uniformity, while the majority of commercial lines showed negative effects.
These findings suggest experimental ELS lines contain alleles for fiber length and
strength not present in this particular set of commercial cultivars. Experimental ELS
lines exhibited negative GCA effects for lint percent, which suggests further selection is
needed for these lines to be commercially competitive. Performances of F2 lines suggest
differences in fiber traits are predominantly due to additive gene action. Furthermore,
data suggests alleles for fiber length and strength is present in the experimental ELS
lines not present in the commercial cultivars. F2 progeny exhibited moderate heritability
for all fiber traits. Sufficient variability exists within selected F2 progeny to select for
phenotypes exhibiting improved fiber quality over commercial cultivar potential with
similar agronomic qualities of commercial cultivars. The ELS lines are a useful source
of germplasm for plant breeders looking to improve fiber qualities in their programs.
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Mkula, Ntombizanele Precious. "Allelopathic interference of silverleaf nightshade (Solanum elaeagnifolium Cav.) with the early growth of cotton (Gossypium hirsutum L.)." Diss., 2007. http://hdl.handle.net/2263/27474.
Full textAbstract:
Silverleaf nightshade (Solanum elaeagnifolium), a perennial broadleaf weed, has become a serious pest in many semi-arid areas of the world. Control of silverleaf nightshade is confounded by its ability to produce thousands of viable seeds from a single mother plant, a deep and well-developed root system and the ability to propagate vegetatively from creeping lateral roots, root fragments and from rhizomes. Exacerbating factors are longevity of its propagules in soil, particularly under adverse environmental conditions. Currently, in South Africa, it is one of the more serious weeds in cotton (Gossypium hirsutum L.) production, where its interference results in remarkable loss of product quantity and quality. Research has been done on the competition aspect of silverleaf nightshade with cotton but there is a serious lack of information on the allelopathic aspect. In this study, a series of experiments that included laboratory and glasshouse experiments were conducted to evaluate the allelopathic interference of silverleaf nightshade on early growth of cotton. Cotton seeds were exposed to silverleaf nightshade extract solutions or planted in soil into which silverleaf nightshade leaf material or ripe berries were incorporated. In all the experiments attempts were made to avoid or to reduce, at least, the influence of factors that could be potentially confounding. In this regard, PEG-6000 was used to evaluate the sensitivity of crop parameters to the osmolality of test solutions in order to ensure that osmotic inhibition was not a confounding factor in the bioassays where the biological activity (phytotoxicity) of plant extracts were assessed. Competition for growth factors was the other major potentially confounding factor that was considered throughout, and steps were taken to negate its influence. Germination and early seedling growth of cotton cultivars Sicala, CA 223, Siokra V15, Tetra and Delta Opal were inhibited by test solutions (silverleaf nightshade extracts) and by soil-incorporated residues of silverleaf nightshade. Inhibitory effects of silverleaf nightshade solutions were observed when either a layer of filter paper or a thin layer of soil or quartz sand was used as substrate. In both laboratory and pot experiments, it appeared that cotton cultivar Sicala was the most sensitive to allelochemicals contained in extracts and residues of silverleaf nightshade. This finding of differential tolerance of crop cultivars towards allelochemicals contained in a weed is a rare occurrence in allelopathy research. Berries of silverleaf nightshade were generally more inhibitory to cotton than leaf material. For both types of plant material used, residues lost their inhibitory effect over time, probably as decomposition of allelopathic compounds in soil progressed. Information obtained from this study can be viewed as knowledge that contributes to the bridging of the gap between identification and isolation of allelochemicals from silverleaf nightshade, and confirmation of silverleaf nightshade allelopathy under natural conditions. Experiments involving soil as growth medium, in particular fieldwork, are needed to verify the validity of these findings under natural conditions.Dissertation (MSc(Agric) Agronomy (Weed Science))--University of Pretoria, 2007.
Plant Production and Soil Science
MSc(Agric)
unrestricted
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Nelson, John Randall. "Site-specific management and remote sensing based plant growth regulator application decisions in cotton (Gossypium hirsutum L.)." 2006. http://www.lib.ncsu.edu/theses/available/etd-08172006-121041/unrestricted/etd.pdf.
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Onanuga, Adebusoye. "A HYDROPONIC APPROACH TO EVALUATE RESPONSES TO NUTRIENTS AND PHYTOHORMONES IN COTTON PLANTS (Gossypium hirsutum L.) GROWTH AND DEVELOPMENT." 2013. http://hdl.handle.net/10222/44678.
Full textAbstract:
Cotton plant growth and development, as well as monitoring nutrient use efficiency were evaluated using hydroponic approach. Two set of experiments were conducted to determine the influence of phosphorus (P), potassium (K) and PK and exogenous application of Indole-3-acetic acid (IAA), gibberellic acid (GA3), zeatin (Z) and their combinations on growth and development of cotton plants (Gossypium hirsutum) grown hydroponically. In the nutrient solution experiment, cotton vegetative growth was positively influenced by low P (half strength Hoagland standard solution), low K (one-sixth strength Hoagland standard solution) and high PK treatments (Hoagland standard solution). Phytohormone experiment negatively supported vegetative growth except root length at 43 days after transplanting (DAT). The nutrients levels applied significantly favoured NPK uptake by cotton plants while exogenous phytohormones application did not affect NPK uptake by cotton plants, except N uptake by stem. Low P and low K treatments estimated to have high nutrient use efficiency (NUE). For chlorophyll formation, low K and high PK significantly increased formation of chlorophyll a, b and total ab while the application of GA3, IAA, Z and IAA x GA3 x 2Z treatments significantly increased chlorophyll a, b and total ab at 80 DAT only. Low K and low P treatments stimulated endogenous phytohormone contents in the cotton plants. In the phytohormone experiment, cotton plants treated to IAA x GA3 x Z increased endogenous phytohormone contents in the cotton plants. Low P, low K, high PK treatments and phytohormones treatments significantly increased root area, root volume and root activity. Low P, low K and high PK treatments applied significantly influenced residual level of P and K in the hydroponics while phytohormone treatments did not affect residual level of P and K except at 43 DAT. Evapotranspiration rate was high at early and reproductive stages of plant growth. This report shows the response of mineral nutrients and phytohormones to support growth and development of cotton plants grown hydroponically.Description as in abstract