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McKimmie, Tim, and Albert Dobrenz. "Salt Tolerance During Seedling Establishment in Alfalfa." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/203790.
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Deposition of salts from irrigation water is an increasing concern for Arizona farmers and agronomists. Selection for salt tolerance during the seedling stage has been undertaken over the past three years. Yield tests were conducted in greenhouses and a significant increase in dry matter production was shown in the selected material.
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Carter, Sara Katherine. "TOLERANCE OF SEEDLING TURFGRASS SPECIES TO ALS INHIBITING HERBICIDES." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/429.
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Acetolactate synthase (ALS) inhibiting herbicides are commonly used to eliminate weeds from mature turfgrasses. Field trials were conducted from 2004-2006, testing ALS herbicides for preemergence and early postemergence activity on newly seeded turfgrasses, using four species: Riviera bermuda, Zenith and Companion zoysia, L- 93 creeping bentgrass, and Poa annua L. Data collected were phytotoxicity and percent turf cover. Bermuda and zoysia herbicides were metsulfuron-methyl (42 g ha-1), trifloxysulfuron (29 g ha-1), flazasulfuron (53 g ha-1), foramsulfuron (30 g ha-1), bispyribac-sodium (112 g ha-1), and rimsulfuron (35 g ha-1). Treatments occurred the day of seeding and two-three weeks after seeding. Flazasulfuron, trifloxysulfuron and bispyribac-sodium caused significant damage in all treatments. Data suggests that bermuda and zoysia are tolerant of seedling treatments of foramsulfuron, rimsulfuron, and metsulfuron-methyl at these rates. Bentgrass and P. annua herbicides were foramsulfuron (15 and 30 g ha-1), siduron (2803 g ha-1), bispyribac-sodium (49 g ha-1), and paclobutrazol (281 g ha-1). Treatments occurred the day of seeding, two and four weeks after seeding. Foramsulfuron at 15 and 30 g ha-1 caused significant damage regardless of when it was applied. Data suggests that bentgrass and P. annua are tolerant of seedling treatments of siduron, paclobutrazol, and bispyribac-sodium at these rates.
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Myers, Jonathan Andrew. "Seedling carbohydrate storage, survival, and stress tolerance in a neotropical forest." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009262.
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Ali, Rao Sajjad. "The potential for breeding Zea mays (L.) for saline conditions." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387451.
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Oddie, Rachel Louise Annabelle. "Eucalyptus camaldulensis x globulus hybrids for saline land: Production, seedling growth and salt / waterlogging tolerance." Thesis, Oddie, Rachel Louise Annabelle (1996) Eucalyptus camaldulensis x globulus hybrids for saline land: Production, seedling growth and salt / waterlogging tolerance. PhD thesis, Murdoch University, 1996. https://researchrepository.murdoch.edu.au/id/eprint/52423/.
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The rapid development of Eucalyptus globulus Labill. plantations for the paper and pulp industry and the increasing problem of dry land salinity in the south west of Western Australia, stimulated the development of a breeding programme aimed at producing a Eucalyptus L'Herit. hybrid that combines the salt / waterlogging tolerance of selected E. camaldulensis Dehnh. clones with the high pulp quality and yield of selected E. globulus subsp. globulus families.
Controlled pollination techniques were used to produce intraspecific and interspecific hybrids. Unilateral cross incompatibility was observed between the two species. When E. globulus was used as the female parent E. camaldulensis pollen tubes failed to grow the entire length of E. globulus styles. However when E. camaldulensis was used as the female parent, interspecific crosses were successful. Five E. camaldulensis salt tolerant clones and four E. globulus families (three with known pedigree) were used to produce the crosses.
E. camaldulensis flowers were emasculated just before operculum shed. Stigma receptivity, assessed by seed production, peaked in E. camaldulensis three days after emasculation. This coincided with the style turning red and the stigma becoming enlarged, yellow and sticky. Reasonably high levels of seed (> 25 seeds per capsule and > 65 % capsule set) could also be produced when flowers were pollinated before or after day three (days 0 - 5). Pollen placed on green, dry stigmas (days 0-2) remained ungerminated until stigmas began to enlarge and become sticky. The timing of stigma receptivity varied between the E. camaldulensis genotypes.
The number of seeds produced per capsule when E. camaldulensis was selfed was 87 % less than when the clones were outcrossed. The interspecific hybrids showed a 77 % reduction in seed set compared to outcrossed E. camaldulensis. In both cases the mechanism of the partial incompatibility was not operating in the style.
Further barriers to the hybridization of E. camaldulensis and E. globulus were manifested as a high percentage of seedlings with abnormalities compared to outcrossed E. camaldulensis. The intensity of barriers to interspecific hybridization varied, with families exhibiting from 50 to 97 % abnormal progeny.
Seedlings at the two leaf stage and at six to eight months old were scored for a number of morphological characters. These were cotyledon length, cotyledon width, depth of cotyledon emargination, petiole length, lamina length, lamina width at the widest point, the vertical distance between the axillary buds at the fifth node and leaf angle (angle between the main stem and the midvein of the lamina). Overall the morphology of the hybrids (assessed by these characters) tended to be intermediate between the two parents, but more like E. globulus than E. camaldulensis.
A small number of seedlings produced from E. camaldulensis x globulus crosses were morphologically very similar to E. camaldulensis. Allozyme analysis was used to determine the parentage of these individuals. Of the six enzyme systems studied malate dehydrogenase (MDH, E.C. 1.1.1.37) and 6-phosphogluconate dehydrogenase (6PGD, E.C. 1.1.1.44) were the most useful in identifying E. camaldulensis x globulus hybrids. The seedlings from hybrid families with similar morphology to E. camaldulensis were identified as E. camaldulensis. All other seedlings from hybrid families were clearly of hybrid origin. The possible cause of the seed contamination in the controlled crosses is discussed.
Seven month old seedlings were screened for salt / waterlogging tolerance in a glasshouse trial. Seedlings were placed in tanks and flooded to the sand level in the pots with one fifth Hoagland nutrient solution number two for one week. The following and each subsequent week 50 mM NaCl was added to the tanks until the NaCl concentration reached 350 mM. This concentration was held for three weeks. E. camaldulensis had a greater salt / waterlogging tolerance than E. globulus based on survival and height growth rate. The performance of the hybrid families was intermediate between the two parental species. Genotypes with superior tolerance of saline waterlogging were micropropagated for further field trials.
The potential of selected E. camaldulensis x globulus genotypes is discussed in light of the preliminary results of the breeding programme.
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Mwando, Edward Kulecho. "The genetics of barley (Hordeum vulgare) salinity tolerance during germination and the instantaneous seedling endurance." Thesis, Mwando, Edward Kulecho (2021) The genetics of barley (Hordeum vulgare) salinity tolerance during germination and the instantaneous seedling endurance. PhD thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/60357/.
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Salinity limits crop production through osmotic and ionic stress in combination with oxidative strain and nutrient imbalance. Osmotic tolerance, ionic exclusion, and tissue tolerance are some of the adaptive mechanisms in plants when exposed to salinity stress. These physiological adaptive mechanisms are quantitative in nature and are manifested genetically by affecting ~ 8% of genes expression. Barley, the fourth most important cereal crop in the world, is relatively salinity tolerant. However, salinity causes a significant reduction in its growth and grain yield. Adaptation to salinity in barley is varied with growth stage where germination and early growth stages are the most sensitive. This is because excessive salt accumulation in the rhizosphere affects the germinating seed and the subsequent developmental processes including revitalization of plants development after exposure to salinity stress during the sprouting stage. Studies are yet to close the lack of information between the germination and/or seedling stage salinity tolerance, and the genotypic differences in developing young plants regeneration after exposure to salinity stress. The current study explored the genetics of salinity tolerance during the germination stage and the seedling survival in barley after germination under salinity stress (NaCl). To detect the genetic loci and candidate genes responsible for salinity tolerance in barley during germination and early growth stages, four barley populations comprising of a diversity panel of 350 accessions from across the globe, two doubled haploid (DH) populations (CM72/Gairdner and Skiff/CM72), and a back-cross population of CM72/Gairdner/*Spartacus CL were used for phenotyping and mapping. These germplasm sets were exposed to different levels of salinity stress (75, 90, 120 AND 150 mM NaCl) along with a control treatment (deionized water) and various phenotypic traits recorded at germination and early seedling stages. Genome-Wide Association (GWAS) analysis was conducted on a diversity panel of 350 accessions using ~24,000 genetic markers, where 19 Quantitative Traits Nucleotides (QTNs) were detected across all 7 barley chromosomes and 4 genes predicted for salinity tolerance at germination. A study with CM72/Gairdner DH population mapped six Quantitative Traits Loci (QTLs) on chromosomes 1H, 3H and 4H for traits associated with seedling survival under salinity stress. Three QTLs on 1H (1) and 3H (2) with closely linked significant markers that were detected in more than one salinity survival traits were proposed as the regions with highest probability of having candidate genes. To narrow down the location of genetic regions associated with salinity tolerance at germination on chromosome 2H, a major QTL was fine–mapped using CM72/Gairdner and Skiff/CM72 DH populations, F2 and F3 generations of CM72/Gairdner/*Spartacus CL to a region of ~ 0.341 Mb and designed 2 diagnostic markers. Further, this study reported two Receptor-like protein kinase 4 as the candidate genes for enhanced germination under salinity stress. The diversity of seven reported genes in barley was explored further in 40 different species where three of them; dehydration-responsive element-binding (DREB) protein, somatic embryogenesis receptor-like kinase and aquaporin genes, were found to be the most varied. While all three gene families show great diversity in most plant species, the DREB gene family was more diverse in barley than in wheat and rice. Sixty-five barley homolog genes were identified from salinity tolerance genes characterized in Arabidopsis, maize, rice, soybean, and wheat. Besides, the homologs have been reported to express themselves in first three barley’s developmental stages. The results of this study provide new genetic resources and information for further functional characterization of the identified candidate genes and to improve salinity tolerance at germination and early seedling stage via genomic and marker-assisted selection (MAS) in barley. The findings in this thesis together with other existing information will facilitate breeding and release of new high yielding barley varieties that can grow in extreme environment including saline soils of the world.
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Dowling, Christopher W. "Seed and Seedling Tolerance of Cereal, Oilseed, Fibre and Legume Crops to Injury from Banded Ammonium Fertilizers." Thesis, Griffith University, 1998. http://hdl.handle.net/10072/366485.
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Processes causing crop establishment damage from ammonium (NH4+) fertilizer placed in close proximity to seed at sowing are generally poorly understood within farming communities of eastern Australia. Currently, the information used to assess establishment hazard includes nitrogen (N) tolerance for a limited range of crop species. Other factors include the N concentration of fertilizer products, with adjustment of the rate expected to be tolerated on the basis of soil moisture and application equipment. Current recommendations were adapted from North American research spanning a period from the start of the century until the 1990s and some recent Australian research (1960s to 1980s) for a limited range of crops and fertilizer types. The incidence of seedling damage from N fertilizer and fertilizer containing other nutrients appears to have grown in recent years. This may be attributed to use of a wider range of NH4+ and other fertilizers, a trend for at-sowing application in zero-tillage and expansion of areas of declining soil fertility, particularly N fertility. Other factors include the sowing of new crops with greater fertilizer sensitivity, low tolerance to establishment loss for high value genetically modified seed and modern designs of sowing and application equipment. The major objective of this research was to investigate ammonia (NH3) tolerance of 10 crop species of importance for eastern Australian cropping systems (maize, Zea mays L.; cotton, Gossypium hirsutum L.; wheat, Triticum aestivum L.; barley, Hordeum vulgare L.; chickpea, Cicer arietinum L.; sorghum, Sorghum bicolor (L.) Moench; canary, Phalaris canariensis L.; canola, Brassica napus L.; panicum, Setaria italica L. and sunflower, Helianthus annuus L.). Experiments were designed to highlight differences among crops in NH3 toxicity and osmotic damage potential for commonly used NH4+ fertilizers. Various strategies were then tested to maintain plant populations within commercially acceptable ranges when affected by NH3 toxicity and/or high osmotic pressure. Tolerance of seeds to NH3 toxicity was evaluated in the field and for atmospheric exposure. Response of various crop species to atmospheric-NH3 exposure showed that certain species responded differently in their germination, coleoptile growth and radicle growth in a closed system. Using these 3 parameters as indices of crop response to NH3 toxicity revealed different ranking for some species; the same species showed a different critical NH4+ concentration for each parameter. Exposing seeds above 200 x 10-4 M NH4OH for 72 h was sufficient to significantly reduce or inhibit germination of all 10 species tested. Seed of most species were unaffected by exposure above 20 x 10-4 M NH4OH. Species rank, combining tolerance for germination, coleoptile growth and radicle growth was established to relate to likely performance in the field. Decreasing order of tolerance for monocot species was: maize > sorghum > wheat = barley > panicum > canary and for dicot species chickpeas > cotton > sunflowers > canola.
A range of physical and chemical seed characteristics was correlated with NH3 tolerance to investigate tolerance mechanisms. For monocot species, tolerance was related to the seed surface area/volume ratio suggesting that diffusion resistance was an important parameter whereas for dicot species N concentration of seed was negatively correlated with tolerance.
In field experiments where NH4+-fertilizers were placed with seeds, difference between species in their tolerance of atmospheric-NH3 was insufficient to describe effects of NH4+-fertilizers on crop emergence. Crop species fell into 3 response categories; high (maize, sorghum, barley and wheat), medium (cotton, canary and sunflower) or low (canola, chickpea and panicum) tolerance to soil NH4+-N. Soil NH4+-N concentrations tolerated by the medium and low tolerance group was 50 % and 15 to 25 % respectively, that of the high tolerance group. Generally, NH3 tolerance response for species such as wheat, barley and sorghum was found similar to current recommendations for urea (~0.5 g/m N as urea) but there were significantly different responses to NH4+-N from different NH4+-fertilizer products, that are not recognised in current recommendations.
Crop species were ranked for sensitivity to mono-ammonium phosphate (MAP), di-ammonium phosphate (DAP), triple superphosphate (TSP), urea and ammonium nitrate, and categorised according to the fertilizer rate at which significant establishment damage occurred. Ranking of crop species for NH3 toxicity was generally similar across experiments but the NH4+-N rate tolerated varied with experimental conditions. Urea and DAP caused larger reductions in establishment than equivalent NH4+-N rates from MAP or ammonium nitrate. The "safe" rate for ammonium nitrate (1 g/m NH4+-N) was approximately twice that of urea at equivalent NH4+-N rates. Usually between 20 and 30 % more NH4+-N was tolerated for MAP than for DAP. In the absence of NH3 toxicity, osmotic effects of fertilizer products delayed and occasionally inhibited germination. There was significant difference among species in osmotic tolerance; cotton, maize and sorghum (< -0.3 MPa) were more tolerant than sunflower or soybean (> -0.2 MPa). Strategies to improve crop establishment in the presence of NH4+ fertilizer such as increasing seeding rate, adding water to the seed furrow, changing fertilizer N source and chemically modifying hydrolysis of urea were identified and tested. For low to moderate rates of seed placed NH4+-N, increasing barley seeding rate from 25 to 40 kg/ha was found to be successful strategy to maintain establishment when urea rate was increased from 1.1 to 2.3 g/m of seed row. Changing the fertilizer N source and modifying hydrolysis of urea were successful in lowering soil NH4+ around the seed and thus reducing establishment losses, but osmotic effects also limit the maximum fertilizer application rates. The added cost of these strategies may prevent their widespread adoption. Complex interactions between crop species, fertilizer product, soil texture and moisture, and application equipment highlighted by the results of these experiments, suggest that simple decision tools are insufficient to provide fertilizer recommendations that meet the demands of modern agriculture. A computer based decision support programme, Fertsafe, was developed during this study from experiments conducted and papers reviewed, to provide "safe rate" recommendations to apply fertilizer at sowing for a range of crop species, fertilizers, soils and sowing conditions of eastern Australia. Changes to fertilizer application equipment, other crops and fertilizer products will require ongoing research continuously improve and update this decision support tool.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Australian School of Environmental Studies<br>Full Text
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Parajuli, Suman. "Influence of Tomato (Solanum lycopersicum L.) Seedling Grafting on Plant Growth, Fruit Yield and Quality, and Disease Tolerance." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31651.
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Influence of tomato (Solanum lycopersicum L.) seedling grafting on the plant growth, fruit yield and quality, and disease tolerance were investigated using 3 cultivars (Big Beef, Celebrity, Cannonball) as scions and two Solanum species (B-blocking, Maxifort) as a rootstock in a randomized complete block design with three replications. The grafted plants were statistically higher in values for stem diameter, leaf chlorophyll, and fruit carotenoid contents. Similarly, the scion/rootstock combination ‘Big Beef/Maxifort’ and ‘Big Beef/B-blocking’ had prolonged days to maturity and gives a higher yield than the non-grafted ‘Big Beef’. Grafting seedling on ‘Maxifort’ and ‘B-blocking’ rootstocks improves the fruit quality like titratable acidity (TA), fruit firmness, but didn’t alter the pH, total soluble solid (TSS), lycopene and TSS/TA. Also, grafted treatment ‘Big Beef/Maxifort’ was found to be a highly disease resistant treatment when compared to the ‘Big Beef’ control with mean relative effect 0.074.
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Kibret, Kidist Bogale [Verfasser]. "Systems biological analysis of seedling vigour and osmotic stress tolerance in oilseed rape (Brassica napus L., Brassicaceae) / Kidist Bogale Kibret." Gießen : Universitätsbibliothek, 2017. http://d-nb.info/113657008X/34.
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Jibo, Abdullahi Umar. "Variation in drought tolerance and morphological plasticity among two provenances of Acacia senegal (Senegalia senegal) seedling in North Eastern Nigeria." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227119.
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Gadeh, H. M. "The effect of compost and priming on the salt tolerance of bread wheat (Triticum aestivum L. cv. S-24 and cv. Slambo) during germination and early seedling establishment." Thesis, Coventry University, 2013. http://curve.coventry.ac.uk/open/items/f0bd31e5-d16c-4435-993a-ab1ec64d7bc3/1.
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Soil salinity and the arid climate in Libya are major constraints in agriculture and predominantly in foodstuff production which are limiting wheat production and yield. The effect of pre-sowing seed treatments with 50 mM of KCl, NaCl, CaCl2, and distilled water as hydropriming on germination and early seedling growth in two wheat (Triticum aestivum L.) cultivars S-24 (tolerant) and Slambo (untested before) under 0, 100, 200 and 300 mM NaCl concentrations was examined. CaCl2 was the only priming treatment that significantly improved the germination percentage, germination rate, and mean germination time in both cultivars under almost all NaCl concentrations. Thus, priming with CaCl2 was selected for further experiments. In the greenhouse, seeds primed with 50 mM of CaCl2 also improved the emergence percentage, emergence rate, shoot and root length, and fresh and dry weight of shoots and roots of both cultivars under all NaCl concentration except at 300 mM where the emergence was completely inhibited. The response of wheat cultivars to three compost treatments including cow manure compost (CC), greenwaste compost (GC) and 50:50 mixture (mix) between them and sand at percentage inclusions of 10 and 30 % by weight under 0, 100, 200, and 300 mM of NaCl was also investigated. Among all compost treatments, 30% GC and 30% mix were the best treatment and improved almost all growth parameters under salt stress, and 30% GC was also the only treatment that had any emergence at 300 mM NaCl. 30% GC and 30% mix were selected for further experiments. The effect of the combination of the selected priming agent (CaCl2) and the best two compost treatments (30% GC and 30% mix) on the emergence and early seedling growth of both cultivars was tested. The results showed that all the treatments enhanced plant growth parameters including seedling ion uptake in both cultivars, with preference to primed seeds sown in 30% GC. The treatments had the following order of the performance of both cultivars under salt stress. Primed seeds sown in 30% GC > unprimed seeds sown in 30% GC > primed seeds sown in 30% mix > unprimed seeds sown in 30% mix. This enhancement is possibly due to the provision of Ca2+ and / or the improvement in the availability of water as both of them were improved by the application of priming and compost.
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Hoven, Brian Michael. "The Effect of Emerald Ash Borer (Agrilus Planipennis)-Caused Ash Mortality and White-Tailed Deer Abundance on Understory Invasive Shrubs and Forest Regeneration." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1627656584529987.
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Malmqvist, Cecilia. "Planting and survivability of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in Sweden : Questions of seedling storability, site preparation, bud burst timing and freezing tolerance." Doctoral thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-59933.
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The non-native Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) has been grown to a limited extent in the southern part of Sweden since the early 1900s. A more extensive use has probably been curtailed by its known susceptibility to damage by frost, pine weevil and other pests. Limited access to vital seedlings of suitable provenances has also restricted its more widespread growth. The need for valuable species that will grow well through ongoing climate change has increased the interest for Douglas fir in Sweden. This thesis addresses a number of important questions relating to the planting of Douglas fir in Sweden: seedling storability, freezing tolerance, timing of bud burst, frost damage and seedling response to site preparation. Seven Douglas fir provenances originating from British Columbia, Canada were used in the experiments and where applicable, compared with a local provenance of Norway spruce (Picea abies (L.) Karst.). The early bud burst of interior Douglas fir provenances, observed both in greenhouse tests and in the field, results in a high risk of damage by late spring frost. This type of damage does not seem, however, to be fatal and does not obviously retard the early growth of seedlings. The difference in growth between coastal and interior provenances was insignificant, but survival was greater for interior than for coastal provenances. All the provenances of Douglas fir studied showed a later development of freezing tolerance of shoots and roots in the autumn than Norway spruce, with the coastal provenances developing such tolerance even later than interior provenances. This could be a contributory cause for the severe damage by winter desiccation observed on seedlings of coastal origin. A thorough site preparation proved to be an effective way to increase survival and root growth. Interior provenances of Douglas fir became ready for storage earlier in autumn than coastal provenances. When freezing tolerance of shoots had increased sufficiently, Douglas fir seedlings could safely be kept in frozen storage using the same procedures used for Norway spruce. The results emphasise the need to gain further knowledge about how the remaining obstacles to establishment of Douglas fir could be reduced with different silviculture methods.
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Rubio, Neto Aurélio. "Viabilidade de embriões de macaúba [Acrocomia aculeata (Jacq.) Lood. Ex Mart.] e babaçu (Orbignya phalerata Mart.) em função da maturação e secagem dos frutos." Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/3729.
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Previous issue date: 2013-06-26<br>Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq<br>The objective of this study was to evaluate the physiological quality of embryos of babassu (Orbignya phalerata Mart.) and macaw palm [Acrocomia aculeata (Jacq.) Lood. Ex Mart.] according to the drying speed in order to optimize the already existing drying process as well as to propose a more efficient method for the in vitro establishment of macaw palm and babassu. It was observed that for both species under study, the temperature of 37±2°C promoted loss of water less than 57±2°C. However, it was more efficient because it did not inhibit the embryo during this process, ensuring high germination rates, even in seeds with 9% of water content for babassu and 19% for macaw palm. The adoption of the tetrazolium test, initially proposed for macaw palm, which uses salt at 0.5% and imbibition for 4 hours, allowed to distinguish different classes of vigor also in the babassu. Drying at 37°C favored the extraction of intact seeds and consequently the removal of embryo for in vitro culture of macaw palm. There was no difference in the in vitro germination of embryos extracted from fruit with different colors of the epicarp, which was approached as different maturity classes of macaw palm. The in vitro germination of embryos was enhanced with the addition of 30-40 g L-1sucrose in the culture medium. Thus, it is found that drying the fruit of babassu and macaw palm at 37°C ensures effectiveness in the process, since it allows better extraction of seeds or embryos which enable to achieve high in vitro germination rate within 60 days, making the time for production of seedlings much shorter.<br>Objetivou-se com este estudo avaliar a qualidade fisiológica de embriões de macaúba [Acrocomia aculeata (Jacq.) Lood. Ex Mart.] e babaçu (Orbignya phalerata Mart.) em função da velocidade de secagem, a fim de otimizar o processo de secagem já existente, bem como, propor uma metodologia mais eficiente para o estabelecimento in vitro de macaúba e babaçu. Verificou-se que para as duas espécies em estudo, a temperatura de 37±2°C promoveu perda de água inferior a de 57±2°C. Entretanto, foi mais eficiente pelo fato de não inviabilizar os embriões durante esse processo, garantindo elevadas taxas de germinação, mesmo em sementes com teor de água de 9% para o babaçu e de 19% para a macaúba. A adoção do teste de tetrazólio proposto inicialmente para macaúba, que utiliza o sal a 0,5% e embebição por 4 horas, permitiu a distinção de diferentes classes de vigor também no babaçu. A secagem a 37°C favoreceu a extração de sementes intactas e, consequentemente, remoção do embrião, para cultura in vitro de macaúba. Não se verificou diferença na germinação in vitro de embriões extraídos de frutos com diferentes cores do epicarpo, que foi abordado como diferentes classes de maturação de macaúba. A germinação in vitro dos embriões foi favorecida com o acréscimo de sacarose no meio de cultivo de 30 a 40 g L-1. Dessa forma, verifica-se que a secagem dos frutos de macaúba e babaçu a 37°C garante efetividade no processo, visto que, permite melhor extração das sementes e embriões, com isso, são alcançadas elevadas taxas de germinação in vitro em até 60 dias, encurtando muito o tempo de produção da muda.
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Schnaithmann, Florian [Verfasser], Klaus [Akademischer Betreuer] Pillen, and Gunter [Akademischer Betreuer] Backes. "Mapping of quantitative trait loci regulating nitrogen stress tolerance and leaf rust seedling resistance in two selected populations derived from crosses between exotic and elite barley : [kumulative Dissertation] / Florian Schnaithmann ; Klaus Pillen, Gunter Backes." Halle, 2016. http://d-nb.info/1116951517/34.
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Lyall, Rafe. "Regulation of desiccation tolerance in Xerophyta seedlings and leaves." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22853.
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A small, diverse group of angiosperms known as resurrection plants display vegetative desiccation tolerance and can survive loss of up to 95% of cellular water, a feat only seen in the seeds and pollen of other angiosperms. Xerophyta humilis is a resurrection plant native to Southern Africa that has been the target of previous transcriptomic and proteomic studies into the mechanisms of plant desiccation tolerance. The aim of this study was to investigate the hypothesis that vegetative desiccation tolerance is derived from the networks that control desiccation tolerance in seeds and germinating seedlings in angiosperms, particularly the epigenetically silenced seed maturation genes. Germinating seedlings of X. humilis and the related resurrection plant X. viscosa were found to be VDT from the earliest stages of germination, and exhibited the characteristic vegetative trait of poikilochlorophylly as seen in mature leaves. The X. humilis desiccation transcriptome comprising 76,768 distinct gene clusters was successfully assembled from sequencing samples at five relative water contents (100%, 80%, 60%, 40% and 5%) to identify the networks activated in response to water loss. Desiccation was associated with successive waves of transcription factor induction, as well as widespread down-regulation of histone modification enzymes. Many seed-specific genes, such as late embryogenesis abundant (LEA) proteins, seed storage proteins and oleosins, were induced in vegetative tissue. LEA transcripts in particular were highly up-regulated during desiccation, and the large number of distinct LEA transcripts (over 150) suggests possible LEA gene expansion in Xerophyta compared to desiccation-sensitive plants. Components of the PYL/SnRK2/ABF ABA-signalling pathway were also induced, although the ABF transcription factors activated in response to desiccation were most similar to those induced by drought in A. thaliana rather than seed maturation. Of the canonical seed master regulators (such as the LEC1/ABI3/FUS3/LEC2 network and ABI5) only three ABI3 transcripts were expressed, all of which encoded proteins lacking the seed motif-binding B3-domain. The results of this study suggest that vegetative desiccation tolerance in X. humilis is not associated with re-activation of seed master regulators in vegetative tissue, but may instead involve activation of seed genes by vegetative drought response regulators.
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Longenberger, Polly Suzanne. "Development of a screening method for drought tolerance in cotton seedlings." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4765.
Full textAbstract:
The key to an efficient screening method is the ability to screen large amounts of
plant material in the shortest time possible. Unfortunately, due to the complexity of
drought tolerance, a quick and effective screen for this trait has yet to be established.
The research reported herein was designed to evaluate a screening method for drought
tolerance in cotton (Gossypium hirsutum L.) seedlings. Twenty-one converted race
stocks (CRS) and two cultivars were evaluated for seedling drought tolerance on an
individual plant basis. CRS are day-sensitive primitive lines derived from various wild
race stocks that were converted to day neutrality for use in temperate region plant
improvement programs (McCarty et al., 1993). Genotypes were evaluated October -
November 2004 and February - March 2005 under greenhouse conditions at the Norman
E. Borlaug Center for Southern Crop Improvement, College Station, TX. Seedlings
were subjected to three sequential cycles of drought at 15 days after planting (DAP).
Drought cycles consisted of withholding water until the moisture content of "indicator"
cone-tainers, containing Deltapine 491 (DP 491), had an average volumetric water
content of 0.07. Plants were then watered to field capacity and percent survival was
recorded after 48 hours. Genotypes differed in their percent survival following three consecutive drought cycles. Drought cycles 2 and 3 did not contribute to the separation
of genotypes. DP 491 was the most tolerant genotype evaluated. None of the CRS were
more or less tolerant than Acala 1517-99. CRS M-9044-0165 was the most stable
genotype across the two experiments.
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Redar, Sean Patrick. "Low temperature tolerance for Artemisia tridentata seedlings over an elevation gradient." CSUSB ScholarWorks, 2000. https://scholarworks.lib.csusb.edu/etd-project/1760.
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ABIDO, MOHAMMAD SULEIMAN. "MORPHO-PHYSIOLOGICAL EVALUATIONS OF ALEPPO AND BRUTIA PINE SEEDLINGS UNDER TWO DIFFERENT MOISTURE REGIMES (SYRIA, AFFORESTATION, CHLOROPLASTS)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/188171.
Full textAbstract:
The mechanism of drought resistance in the seedlings of Aleppo pine (Pinus halepensis) and Brutia pine (Pinus brutia) was investigated. Both species showed anatomical and morphological adaptations to conserve moisture. Aleppo pine had a thicker cuticle, fewer stomata per unit length, per unit area, and per needle than Brutia pine. A significant number of Aleppo pine stomata were sealed with a waxy layer. Brutia pine had shorter needles, smaller needle surface area, a smaller surface area-to-volume ratio, and longer main root length. The two species were similar in height growth and in the seasonal trend of total non-structural carbohydrates (reducing sugars and starch). Brutia pine had more reducing sugars and less starch in its shoots than Aleppo pine. The latter had a greater amount of total non-structural carbohydrates and starch when the seedlings were subjected to dry down moisture stress. Electron microscopy techniques were used to monitor ultrastructural changes in the chloroplasts of mesophyll cells. Aleppo pine was found to contain chloroplasts exhibiting water stress-related damage at a relative water content of 62 percent, where as Brutia pine chloroplasts were disrupted. It is suggested that future investigations examine the physiological manifestation of drought mechanism at the cellular and molecular levels of both species.
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Stattin, Eva. "Root freezing tolerance and storability of Scots pine and Norway spruce seedlings /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5639-8.pdf.
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Biradar, Sunil Kumar. "Molecular and physiological analysis of chilling tolerance in maize (Zea mays L.) seedlings /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18028.
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Sarkar, Sunita. "Relationship between gibberellins, height and stress tolerance in barley (Hordeum vulgare L.) seedlings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ56695.pdf.
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Alvarez-Clare, Silvia. "Biomechanical properties of tropical tree seedlings as a functional correlate of shade tolerance." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009261.
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Redfield, Edmund Bancroft. "Tolerance mechanisms of black spruce, Picea mariana, seedlings exposed to saline oil sands tailings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60488.pdf.
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Sinclair, Michael N. "Facilitative and competitive tradeoffs between Morella cerifera seedlings and coastal grasses." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5872.
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Morella cerifera is a rapidly expanding native shrub on the Virginia barrier islands which displaces other native coastal species and may interrupt normal sediment dynamics. Barrier islands are considered stressful environments with low nutrients, high solar load, and frequent drought and salt exposure; facilitation often dominates in stressful environments according to the Stress Gradient Hypothesis. The objective of this project was to understand the importance of species interactions with grasses on the growth and physiology of M. cerifera at the seedling life stage through both field and lab experiments. Grasses provided ~1.3°C insulation to shrubs during winter freeze events and a freezing threshold for M. cerifera seedlings was experimentally found between -6°C and -11°C. Seedlings competed for light with grasses during warm months and grew more where grasses were clipped, revealing a tradeoff between winter insulation and summer light competition. M. cerifera shows evidence of ecosystem engineering at the seedling stage by significantly reducing summer maximum temperatures. This enables rapid expansion of M. cerifera across the landscape. As M. cerifera expands, island migration is altered, leading to decreased island stability and increased erosion. Although seedlings are small and relatively vulnerable, this life stage appears to have significant implications for the ecosystem trajectory and stability of the Virginia barrier islands.
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Borsos-Matovina, Vera. "The effect of Ambiol on growth and stress tolerance of Pinus banksiana and Picea mariana seedlings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0007/MQ29456.pdf.
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Siegert, Courtney M. "An investigation of interspecific differences of transpiration in three co-occurring seedling species of varying shade tolerances." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 125 p, 2009. http://proquest.umi.com/pqdweb?did=1889099041&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ogilvy, Tanya. "Regeneration ecology of broadleaved trees in Caledonian Forest." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/831.
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This thesis quantifies aspects of shade tolerance in tree seedlings of species native to the Caledonian pinewood ecosystems of Glen Affric (Highland Region, Inverness-shire). Growth, allocation and morphological responses of 15 species to irradiance under simulated forest canopy light were investigated in a nursery-based shade house experiment. The same responses of four of the 15 species (Ilex aquifolium, Alnus glutinosa, Sorbus aucuparia and Betula pubescens) to different developmental stages of Pinus sylvestris woodland were investigated in the field. The spatial and temporal growth responses of naturally regenerating S. aucuparia seedlings to shade and gap microhabitats were also studied. Data from the shade house experiment enabled further detailed exploration of the relationship between relative growth rates (RGR) and irradiance and potential cross-overs of ranks of growth in high and low light conditions.
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Bloor, J. "Effects of light on the performance of shade-tolerant tropical rainforest tree seedlings." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596725.
Full textAbstract:
This thesis set out to investigate the light responses of shade-tolerant tropical tree species, and to assess whether or not there was a trade-off between shade tolerance and responsiveness to high light. Shadehouse experiments indicated that low-light relative growth rate was positively correlated with that of high light across species, and all seedlings showed typical 'sun' and 'shade' characteristics when grown in high- and low-light survival amongst the species studied. These trends were mirrored in forest-growth plants. Seedling mortality rate in the forest varied across species and was driven by vertebrate herbivory rather than light availability. In the shadehouse studies, seedling light responses did not appear to be confounded by nutrient limitation. Some evidence was found for phylogenetic effects across species, particularly in root morphology. Ontogenetic effects were also found for a number of plant traits, although the significance of these effects was not consistent across species. Species showed changes in growth ranking both across light levels and over time, suggesting a role for shifting competitive hierarchy in promoting species coexistence. The shade-tolerant species studied also varied significantly in the flexibility of their plant traits in response to changes in light conditions. Nonetheless, all species showed significant acclimation to an increase in light in terms of growth, photosynthesis, morphology and architecture. Acclimation to a decrease in light involved a significant decrease in photosynthetic rate and growth across species, but changes in morphology were limited.
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Klinka, Karel. "Survival and growth of western larch seedlings in relation to light availability." Forest Sciences Department, University of British Columbia, 1997. http://hdl.handle.net/2429/651.
Full textAbstract:
Western larch (Larix occidentalis Nutt.) is an important component of the montane forest in southeastern British Columbia. It grows in cool-temperate (IDF and ICH zones) and boreal climates (MS zone and, occasionally, ESSF zone). Larch is considered a very shade-intolerant species which can tolerate low light (partial shading) only during the seedling stage (the first 5 growing seasons). Typically, it regenerates after fire in the open on seedbeds exposed by burning. However, to what extent it tolerates low light and how various light environments affect its survival and growth is not known. The objective of our study was to determine the variation in survival and growth of western larch seedlings in relation to light availability and site conditions.
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Danusevicius, Darius. "Early genetic evaluation of growth rhythm and tolerance to frost in Picea abies (L.) Karst /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5637-1.pdf.
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Zhao, Sheyun. "Induction of freezing tolerance in jack pine seedlings, changes in lipids, oxidation-reduction and antioxidant enzymes during cold acclimation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35380.pdf.
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Guo, Kunmei. "Functional assessment of the role of cyclic nucleotide-gates channel (CNGC10) and salt overly sensitive (SOS1) antiporter in salinity tolerance in Arabidopsis." University of Western Australia. Faculty of Natural and Agricultural Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0063.
Full textAbstract:
Control of intracellular ion homeostasis is pivotal to plant salt tolerance. Plants have developed a number of mechanisms to keep ions at appropriate concentrations. Both transporters and channels on the plasma membrane play important roles in this function. Plant cyclic nucleotide-gated channels (CNGCs) in the plasma membrane are non-selective monovalent and divalent cation channels. So far, most studies on plant CNGCs have been conducted on heterologous systems. In planta, reverse genetic studies revealed the role of different CNGCs in cation uptake, transport and homeostasis. However, there is little information available about the functional characteristics of plant CNGCs. Among the 20 members of this protein family in Arabidopsis, only AtCNGC2 has been functionally identified as an ion channel; therefore, more functional characterization needs to be done on other members of this protein family. Several CNGCs were suggested to be involved in K+, Ca2+ and Na+ uptake and transport, but available information is scarce. This study investigated the relationship between CNGC10 and ion transport in Arabidopsis, with a particular emphasis on the involvement of CNGC10 in salt tolerance. Arabidopsis thaliana wild type (WT) and two AtCNGC10 antisense lines (A2 and A3) were used to characterise the impact of different level of salt stress on (i) root growth, ion concentration in tissues, ion fluxes across the root surface and intracellular ion concentration and pH at the seedling stage, and (ii) photosynthesis and ion concentration in tissues at the flowering stage. Plants of both antisense lines had higher K+ and lower Ca2+ and Mg2+ concentrations in shoots than WT plants when grown in non-salt control 1/4 Hoagland solution. Altered K+, Ca2+ and Mg2+ internal concentrations in AtCNGC10 antisense lines compared with WT plants under non-salt conditions indicated disturbed long distance ion transport, especially xylem loading/retrieval and/or phloem loading. The results of ion fluxes across the root surface also suggested that AtCNGC10 might be involved in transport of K+, Ca2+ and Mg2+ in tissue. Under sudden salt exposure, higher Na+ efflux and smaller K+ efflux in both antisense lines suggested that AtCNGC10 channels are involved in Na+ and K+ transport. The shoots of AtCNGC10 antisense lines A2 and A3 contained higher Na+ concentrations and significantly higher Na+/K+ ratios compared to WT, resulting in impaired photosynthesis and increased salt sensitivity in A2 and A3 than in WT plants. In contrast, seedlings of both antisense lines exposed to salt stress had lower shoot Na+/K+ ratios and longer roots than WT seedlings, indicating that A2 and A3 were more salt-tolerant than WT in the seedling stage, likely because growth is less dependent on photosynthesis in the seedling than in the flowering stage. These results suggested CNGC gene might play a different role during different developmental stages and in various plant organs.
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Yang, Tsung-Hsien, and 楊宗憲. "Studies on salt tolerance of crops seedling." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/78359896911980854051.
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碩士<br>國立嘉義大學<br>園藝學系研究所<br>98<br>The serious ground subsidence and recurrent flooding at some Taiwan’s low-terrain coasts have caused plants to be immersed in stress and their roots rotten or plants dead. Furthermore, these plants cultivated in the salt stress and high-salinity soils due to sea water encroachment and strong evaporation lack water necessary to their growths and grow unhealthily. With ‘Tainumg No. 1’ maize (Zea mays L. ‘Tainumg No. 1’) and ‘Tsuchiu’ cabbage (Brassica oleraceae Capitata Group ‘Tsuchiu’) regarded as object crops corresponding to the salt tolerance and the salt sensitive respectively in this study, we simulate 10 types of salt stress (0.1%~3%) and investigate the salt tolerance of 37 crops’ seedlings by referring to three parameters such as dry matter accumulation ratio, leaf electrolyte leakage ratio, and leaf osmotic potential and 0% as the control group. On the other hand, taking 6 indices such as dry matter accumulation index, leaf electrolyte leakage ratio index, leaf osmotic adjustment index (processed with the 0.5% sodium chloride solution), dry matter accumulation ratio slope, leaf electrolyte leakage ratio slope, and leaf osmotic potential slope (processed with the 0%~0.5% sodium chloride solution) as references to determine seedlings’ salt tolerance, we obtain outcomes shown as follows. (1) ‘Heimeizhen’ maize (Zea mays L. ‘Heimeizhen’): Good salt tolerance crop (maximal dry matter accumulation index = -7%) in contrast to ‘Hungtsuan’ tomato (Lycopersicon esculentum Mill ‘Hungtsuan’) (minimal dry matter accumulation index = -82%. (2) ‘Tainumg No. 1’ maize and lettuce (Lactuca sativa L.): Good salt tolerance crop (minimal leaf electrolyte leakage ratio index = 7%) in contrast to ‘capitata’ lettuce (Lactuca sativa var. capitata) (maximal leaf electrolyte leakage ratio index = 74%). (3) ‘Tainumg No. 1’ maize (seed collecting): Good salt tolerance crop (maximal leaf osmotic adjustment index = -17%) in contrast to ‘Crispa’ lettuce (Lactuca sativa L. ‘Crispa’) (minimal leaf osmotic adjustment index = -94%). Under the same evaluation standards, 13 crops are categorized to the strong salt tolerance level, for instance, ‘Tainumg No. 1’ maize, ‘Tainumg No. 1’maize (seed collecting), ‘Romaine’ lettuce (Lactuca sativa L. ‘Romaine’), ‘Tainan No. 21’ maize (Zea mays L. ‘Tainan No. 21’), water spinach (Ipomoea aquatica Forssk), ‘Tungching’ chinese white cabbage (Brassica compestris L. spp. chinensis var. Communis Tsen et Lee ‘Tungching’), ‘Heye’ chinese white cabbage (Brassica compestris L. spp. chinensis var. Communis Tsen et Lee ‘Heye’), lettuce, ‘Heimeizhen’ maize, djulis (Chenopodium formosanum), floramor (Amaranthus caudatus L.), ‘Heiye’ chinese white cabbage (Brassica compestris L. spp. chinensis var. Communis Tsen et Lee ‘Heiye’), and sesbania (Sesbania roxburghii Merr.); 12 middle salt tolerance crops, for instance, ‘Tainan No. 20’ maize (Zea mays L. ‘Tainan No. 20’), ‘Syuezhen’ maize (Zea mays L. ‘Syuezhen’), pickled cabbage (Brassica campestris L. spp. chinensis var. komatsuna Mastsum.), black mustard (Brassica nigra (L.) W. D. J. Koch), ‘Huazhen’ maize (Zea mays L. ‘Huazhen’), ‘Hsiawang’ chinese white cabbage (Brassica chinensis L. var. Pak-choi ‘Hsiawang’), adzuki bean (Vigna angularis (Wild.) Ohwi et Ohashi), ‘Jizhen’ maize (Zea mays L. ‘Jizhen’), leaf mustard (Brassica juncea L. Czerniak. et Coss), amaranth (Amaranthus mangostanus L.), edible rape (Brassica campestris L. ), and ching chiuan tsai (Brassica compestris L. × Brassica campestris L.); 8 middle salt sensitive crops, for instance, ‘Fongtian’ chinese white cabbage (Brassica compestris L. spp. Chinensis var. Communis Tsen et Lee ‘Fongtian’), ‘Shienku’ winter squash (Cucurbita moschata L. ‘Shienku’), ‘Wanye’ lettuce (Lactuca sativa L. ‘Wanye’), ‘Mu Kua Hsing’ winter squash (Cucurbita moschata L. ‘Mu Kua Hsing’), ‘Guangdao’ chinese white cabbage (Brassica compestris L. spp. chinensis var. Communis Tsen et Lee ‘Guangdao’), ‘Hungtsuan’ tomato, ‘CL5915-930c-1-0-3’ tomato (Lycopersicon esculentum Mill ‘CL5915-930c-1-0-3’), and ‘capitata’ lettuce; 4 salt sensitive crops, for instance, ‘Tsuchiu’ cabbage, ‘Tainumg No. 1’ chinese white cabbage (Brassica compestris L. spp. chinensis var. Communis Tsen et Lee ‘Tainumg No. 1’), ‘Crispa’ lettuce, and mungbean (Vigna radiata (L.) R. Wilcz.). With the regression analysis conducted to 6 salt tolerance indices, the strong correlation is observed between each of these 6 indices and the salt tolerance-weighted index and between each of 2 indices such as leaf osmotic adjustment index and leaf osmotic potential slope and other indices. As two representative indices, the leaf osmotic adjustment index and the leaf osmotic potential slope have the potential to become the simple estimate index for salt tolerance.
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Moolakkal, Antony Reshma. "Screening maize and sorghum for chilling tolerance at seedling stage." Thesis, 2018. http://hdl.handle.net/2097/39023.
Full textAbstract:
Master of Science<br>Department of Agronomy<br>S.V. Krishna Jagadish<br>Low temperature is one of the most limiting stresses to crops that are adapted to tropical and subtropical regions, such as maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench], when introduced into temperate regions. However, no studies have compared the chilling tolerance of maize and sorghum grown together. Therefore, the objective of this research was to screen maize hybrids and sorghum genotypes for chilling tolerance at the germination and seedling stages. With the hypothesis that grain composition of maize and sorghum could lead to varying chilling tolerance, the seeds were analyzed for concentrations of protein, starch, and amylose. Five commercial hybrids of maize and 18 genotypes of sorghum were maintained in growth chambers for 31 days at two temperatures: a control temperature (25/20 °C, day/night) and at chilling temperatures (11/8 °C for 14 days; 12.5/9.5 °C for 14 days, and 14/11 °C for 3 days). Emergence and seedling height were measured during the experiment. At the end of the experiment, shoot dry weight, root dry weight, and leaf area were determined.
Emergence of sorghum under the chilling temperature regime was low (18%). Average height of the emerged sorghum seedlings in the cold temperatures at the end of the experiment was 1.4 cm compared to 55.5 cm in the control treatment. All maize hybrids emerged, but emergence and growth were slowed by the cold temperatures, and average height at the end of the experiment was 4.6 cm compared to 96.1 cm in the control treatment. Shoot dry weight, root dry weight, and leaf area of the sorghum under the chilling temperatures were too small to measure, and, for maize, they were greatly reduced. The results showed that, for sorghum, temperatures should be above 14 °C for emergence, while maize could emerge at lower temperatures.
The analyses of the sorghum seeds showed that Redbine 60 and RTx430 had the highest protein concentrations (15.71% and 15.35%, respectively), and Segaolane had the lowest protein concentration (9.83%). Segaolane had the highest starch concentration (72.71%), and RTx430 had the lowest starch concentration (65.31%). There was an inverse relationship between protein and starch concentrations in the sorghum seeds (R2 = 0.69). Amylose concentrations did not vary significantly among the sorghum seeds. The analyses of the maize seeds showed that Dekalb 51-20 and Pioneer 1151 had the highest protein concentrations (10.98% and 10.95%, respectively), and Pioneer 1105 had the lowest protein concentration (9.26%). Starch and amylose concentrations did not vary significantly among the maize seeds.
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Guei, Robert Gouantoueu. "Seedling evaluation of grain quality responses and drought tolerance in maize." 1988. http://hdl.handle.net/2097/22238.
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Yu, Chen-Jen, and 尤俊人. "Geneto Studies on Cadmium Tolerance at Seedling Stage in Rice Plant." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/63261167561650062175.
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碩士<br>國立中興大學<br>農藝學研究所<br>85<br>Three cadmium tolerant rice varieties ie., Kang Lung Do, Tpipei No.108, and Nohrin No.37, and three sensitive varieties, ie, Kae Bye,Tainung No.28, and Taipei No.103, were used for diallel crosses analysis. The seeds of F1 and F2 were used to do the genetic analysis of cadmium tolerance on the root length root、number、seedling height、total seedling height、shoot dry weight、root dry weight and total seedling dry weight. The results of the experiments are summarized in the followings:
1.Diallel analysis of cadmium tolerance in rice:
(1)The results of diallel analysis indicated that the 7 characters of 6 varieties differed from varieties to varieties and also from different cross combination.
(2)The result of regression analysis were invided into two sections: One was observed that the shoot dry weight、root length、root number、seedling height and total seedling height were controlled by partial dominance. The other was observed that root dry weight and total seedling dry weight were controlled by over dominance
(3)The results of estimates of genetic components and genetic analysis: It was observed that shoot dry weight, root dry weight, seedling height and total seedling dry weight were controlled by the dominance gene and the addition effect of polygene. Root length, and total seedling height were controlled by dominance gene. Mean degrees of dominance on all characters were over dominance. Ratio of total number of dominance to recessive genes in parent were unequal.
2.Phenotypic correlations of F2 populations:
(1)Phenotypic correlations among all pairs of 7 characters were observed. Root length with shoot dry weight and seedling height were significant positive correlation when the population were treated, but untreated population were no significant difference.
(2)Heritabilities are different when the characters and populations were different. For the most results, the heritability of cross combination of Tainung No.28 X Nohrin No.37 were maximal, and of Tainung No.28 X Kang Lung Do were next.
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Luciano, Luis B. Gomez, and 古麥斯. "Establishment of Rice (Oryza sativa L.) Seedling Screening Method for Drought Tolerance." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/36361482684612468853.
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碩士<br>國立屏東科技大學<br>熱帶農業暨國際合作系所<br>100<br>Lack of accurate screening techniques limits the development of tolerant cultivars to drought, which is the most important constraint in rice productivity. A series of experiments were conducted in three stages to evaluate drought tolerance response of indica type rice genotypes at seedling stage: 1) identification of the drought-tolerance potential through observation of root proliferation at different soil depths; 2) selection of soil:sand mixtures and evaluation of drought tolerance responses of rice seedling in nursery trays, as well as in vitro test using PEG-6000 in MS medium; 3) evaluation of drought-tolerance physiological responses at seedling stage in vitro of four previously selected genotypes. Significant genetic variations among genotypes were found in number of root at depths from 0-5 cm, passing 5 and 10 cm, and in accumulated number of root counted from 0-40 cm. According to the root proliferation under drought stress, the genotypes TCS17, TCS10 and TN1 were identified as drought tolerant; genotypes CSY112, and CSY951042 were identified as susceptible. In the in vivo screening of rice seedling, a rapid screening process through soil:sand mixture for rice seedling was established. Leaf drying score was confirmed as a reliable criterion to evaluate water status of rice genotypes seedling under drought stress. The addition of 5 g l-1 of PEG-6000 was found to reduce seedling survival rate (6.67%, 30% and 36.67% for TCS17, CSY112 and TNGS14, respectively), fresh weight and dry weight in vitro, but the increase of dry matter was not significant. For seedling evaluations, genotypes KHS7 and TCS17 showed the best drought tolerance; TS2, TNGS14, and CSY112 were susceptible. The PEG drought-stressed treatment causes reduction in relative growth rate (RGR) and increase proline (Pro) content. Tolerant genotypes showed lower RGR reduction than susceptible genotypes; no differences among genotypes were found in Pro accumulation. The total amount of proteins increased under stress in susceptible genotypes, while decreased in tolerant genotypes. A rapid, simple, and feasible screening system, which combines the use of nursery trays and polyethylene glycol (PEG) tissue culture test, was developed to select drought tolerant rice genotypes at seedling stage under controlled conditions.
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You, Yueh-Ru, and 游岳儒. "Genetic Mapping of Cold Tolerance Roots of Rice (Oryza sativa L.) Seedling." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/72542395556376412686.
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碩士<br>國立臺灣大學<br>農藝學研究所<br>104<br>Mechanical transplanting commonly used in rice (Oryza sativa L.) cultivation usually caused systematic damages to the root system of rice seedlings. The retarded regrowth of adventitious roots may occur as the result of cold current between January and March in Taiwan, and limit nutrient uptake of the seedlings to a point that the seedling leaves become discolored. In this study, a genome-wide association study (GWAS) was conducted on the 44K panel to identify QTLs associated with seedling root regrowth under low temperature treatment. P model was used to reduce the possibility of false positive caused by population structure. We have found a significant region of 18.10 to 18.44 Mb on Chromosome 2, and simplified the significant SNPs in this region into 7 haplotypes. Accessions possessing haplotype 2 performed better than others, and most of them are temperate japonica. A set of 10 cold tolerant and 5 cold sensitive accessions were selected based on both phenotypic and genotypic data, and their root growth difference were verified by subject them to the same cold treatment with extended repeats. However, bi-parental mapping on the F2 population derived from the cross between cold tolerant “Kon Suito” and cold sensitive “Taichung Sen 10” did not reveal any QTL related to the root growth characteristic under cold treatment. It is speculated that while P model was used in the GWAS, the population structure was still not fully corrected. In light of the result of this study, we recommend to conduct bi-parental mapping as a verification measure after GWAS.
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Wen, Chen-Hsin, and 温宸欣. "Detection of Quantitative Trait Loci Associated with Rice Seedling Drought Tolerance Phenotypes." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7pda9z.
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碩士<br>國立臺灣大學<br>農藝學研究所<br>107<br>Rice is an important staple food feeding half of the world population. Drought as the major abiotic stress for rice greatly affects the yield production both in upland and lowland fields. In particular, with the increasing frequencies and severity of drought stress, breeding for drought-tolerant rice is necessary nowadays. Root system architecture (RSA) has been considered as a critical component in drought tolerance because of the important role of roots in water uptake from soil. Various traits contribute together to RSA, such as root morphology including root length, root growth angle and root dry weight, therefore, genetic improvement for an appropriate root system is another promising strategy to elevate drought resistance in rice. In this study, two bi-parental crosses-derived populations: a recombinant inbred lines (RILs) and a F2 population, and a diverse panel were evaluated for their root and drought-tolerant related traits at seedling stage under a hydroponic system with and without an osmotic-associated drought stress induced by polyethylene glycol 6000 (PEG-6000) treatment. Low water potential imposed by PEG in Kimura solution provided a relatively stable experimental condition and allowed us to measure the root-related traits. Single nucleotide polymorphism (SNP) markers of the three populations were obtained following the genotyping-by-sequencing (GBS) approach. With the high-density SNPs, traditional interval mapping (IM), single marker analysis (SMA), and genome wide association study (GWAS) were performed in respective population to identify the genotype-phenotype associations. Our mapping results showed the power of SMA in detecting associations in bi-parental population as compared to the resolution which simple interval mapping can achieve when using the high-density markers. Total 13 genomic regions associated with root-related traits were identified in the three populations, ten of them were searched for candidate genes using three online databases. According to the gene functions, one gene was predicted to be involved in root development and three were characterized to regulate root growth. These four genes are the candidates for future functional analysis to confirm their roles in controlling the root length. Several genomic regions associated with seedling height (SH), rolling score (RS), and heading date (HD) were detected in our F2 populations and diverse panel. We hope the significant regions and SNP markers identified in this study can be utilized in the breeding for drought-tolerant rice cultivars.
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Meeks, Meghyn. "Two Approaches to Evaluate Drought Tolerance in Maize: Seedling Stress Response and Epicuticular Wax Accumulation." Thesis, 2010. http://hdl.handle.net/1969.1/148460.
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We wanted to develop rapid and cost-effective drought tolerance screening methods for mass amounts of germplasm. In 2009 and 2010, we evaluated sixty-two maize inbred lines and their hybrid testcross progeny using seedling stress response and epicuticular wax accumulation as predictors of drought tolerance.
The seedling screening method measured germination, survival and recovery percentages after a series of drought cycles in a greenhouse environment. Eight inbred lines had significantly (P < 0.05) lower germination than the mean estimate, but hybrid testcrosses were not significantly different. The second-to-last day of survival cycle and the second day of recovery cycle best explained genotypic differences for inbred lines and hybrid testcrosses respectively. One inbred line performed well as both an inbred line and hybrid testcross, but poor correlation over the sample set (R2 = 0.0097) was observed.
Flag leaves taken at flowering from plants under full and limited irrigation regimes were sampled for epicuticular wax. Extracted wax weight for genotypes was compared as a percentage of leaf weight (percent wxlfwt) and leaf area (percent wxwta). Eleven genotypes had above average percent wxlfwt as both inbred lines and hybrid testcrosses. Thirteen genotypes had above average percent wxwta as either inbred lines or hybrid testcrosses. Irrigation treatment was not significant (P > 0.05). Heritability of percent wxlfwt was 0.17 (inbred lines) and 0.58 (hybrid testcrosses). Heritability of percent wxwta was 0.41 (inbred lines) and 0.59 (hybrid testcrosses). Correlations (R2) for percent wxlfwt and percent wxwta were 0.19 and 0.03, respectively. Heritability of grams of grain per ear and total grain yield was highest in hybrid testcrosses, with no correlation between inbreds and hybrids.
The developed seedling screening method easily allowed visible drought tolerance observations in inbred lines and hybrid testcrosses but does not seem heritable in our germplasm. Epicuticular wax weight is not an ideal primary trait to evaluate for drought tolerance, but may be a good candidate to observe as a secondary trait in relation to grain yield production in hybrids. Results from this research best supports breeder selection of hybrid germplasm using seedling drought tolerance in conjunction with epicuticular wax.
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王佳琳. "Studiesof electrolyte leakage on the evaluation of the heat tolerance of cabbage seedling." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/e43d22.
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Yu, Sung-Han, and 游松翰. "The Rice Transcription Factor, OsbHLH046, Contributes to Salt Stress Tolerance at Seedling Stage." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/21262582719596674378.
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碩士<br>國立臺灣大學<br>農藝學研究所<br>104<br>Rice basic-Helix-Loop-Helix (OsbHLH) transcription factors (TFs) belong to a multiple gene family and are known to involve in rice growth, development, regulating abiotic stress-responsive gene expression and tolerance of rice. However, because functional redundancy within the super gene family and the pleiotropic effect of individual TF, the specific function for corresponding OsbHLH is not easy to be determined. In this study, we identified an OsbHLH046 TF which is down-regulated by salt and cold treatments from previous microarray result and further confirmed the gene expression by reverse transcription-PCR (RT-PCR). The OsbHLH046-GFP fusion protein showed OsbHLH046 is located in nucleus. Based on the predication of rice eFP browser and the GUS-histochemical staining indicated that OsbHLH046 is expressed in the embryo, seedling root, lateral roots, shoots and anthers. The gene expression was higher at the early germination stage then declined to lower level within 3rd leaf stage. Compared with WT, the Osbhlh046, a Tos17 knocked-down rice mutant, displayed late seed germination, growth retardation, and unable to recover from salt stress at seedling stage. The q-PCR data indicated that salt tolerance related genes in such as OsABI5, OsNHX2 were differential expressed between two plants during recovery stage. The MDA was overaccumulated in Osbhlh046 mutant compared to wild type after recover from salt stress. The ICP-OES elemental analysis also revealed that the Osbhlh046 plant have lower K+ content level, which may not able to maintain the Na+ homeostasis. Meanwhile, the callus of OsbHLH046 overexpression line showed a relative poor regeneration rate. Taken together, these results suggested that OsbHLH046 plays as a positive regulator in seed germination, seedling growth, and contributes to the ability of rice to recover from salt stress.
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Yang, Pei-Wen, and 楊珮雯. "QTL Mapping for Chilling Tolerance at Seedling Stage in Rice (Oryza sativa L.)." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/03054852706471247580.
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碩士<br>國立臺灣大學<br>農藝學研究所<br>100<br>Rice grown in temperate areas is subjected to chilling stress at seedling and booting stages. The purpose of this thesis was to identify quantitative trait loci (QTLs) for chilling tolerance at the seedling stage of rice, using 243 recombinant inbred lines derived from a cross between a chilling-tolerant japonica cultivar, TNG67, and a chilling-sensitive indica cultivar, TN1. The phenotypes of chilling tolreance at seedling stage was scored by the measurements of the survival rate and the artifical chilling-tolerant classes. The results showed that the correlation coefficient between the survival rate and the artifical chilling-tolerant classes was 0.50. Both phenotypic measurements identified two major QTLs on the same chromosomal region: one on chromosome 6, the other on the chromosome 11. The former QTL linked to the SNP marker RC6-1, and the latter QTL linked to the SNP marker RC11-11. The QTLs for the survival rate under chilling stress were named qCTSS6.1 and qCTSS11.1, and the QTLs for the chilling-tolerant classes were named qCTS6.1 and qCTS11.1 The combined effects of the two QTLs were able to explain approximately 30% of phenotypic varions within the genetic mapping population, for either the survival rate or the chilling-tolerant classes.
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LI, ZE-MING, and 李澤民. "Roles of abscisic acid and polyamines in chilling tolerance of rice (Oryzasativa L.) seedling." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/76915540306745741928.
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Hlophe, Nhlanhla Lucky, and 何洛菲. "Establishment of an Effective Seedling Screening Method for Drought Stress Tolerance of Soybean Cultivars." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/52376766855607558049.
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碩士<br>國立屏東科技大學<br>熱帶農業暨國際合作系<br>102<br>The contents of Abstract in This Thesis:
An important aspect in studies dedicated to drought tolerance in soybeans is the assessment of the degree of drought tolerance of different cultivars. Thus, there is urgent need to determine accurate and effective seedling screening method for drought stress tolerance. The objective of this research was to establish an effective seedling screening method for drought stress tolerance of soybeans cultivars. The first trial was conducted to determine a better container which could show an appropriate gradient slope of soil moisture drop for drought tolerance screening. Results obtained from the plastic boxes showed a good steady drying soil moisture slope for seedling screening from the 3rd to the 6th day. Therefore, boxes were used to develop an appropriate seedlings screening technique for soybean cultivars under water stress environment at seedling and flowering stages. Five soybeans cultivars (KS6, KS7, KS8, KS9 and A), were carefully studied for
morphological and physiological markers contributing to drought tolerance both under control and drought stress conditions. Drought stress for seedling screening was imposed in four plastic screening boxes after 10 days from seedling emergence. Significant differences were observed as water stress affected all parameters. Net photosynthesis rate, leaf senescence, leaf area, proline content plant death and yield were the main parameters used to characterize cultivars from drought tolerance and susceptibility. Based on seedling screening, cultivar KS 9 proved to be drought tolerant compared with the check cultivar followed by KS7, KS 6 which showed mild tolerance while KS8 was more susceptible. Results from drought stress initiated at flowering stage showed cultivars KS 8 and KS 6 to be drought tolerant and KS 9 and KS7 as mild with cultivar A as susceptible in terms of all the parameters measured. In conclusion the results indicated that later developmental stages were also sensitive to water deficit. And, the performance of genotypes tolerance to drought can vary from seedling stage. The results further proved that the polypropylene plastic box seedling screening method can be used effectively to screen dryland crops for drought tolerance.
Keywords: soybeans, screening technique, drought stress, cultivars
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Dai, Hung-Yu, and 戴宏宇. "QTL Mapping for Cold Tolerance of Rice Seedling in the Cross between TNG67 and TN1 Varieties." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/64422708027381558326.
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碩士<br>國立臺灣大學<br>農藝學研究所<br>98<br>To understand the genetic factors for chilling tolerance at rice seedling stage, a BC1 population from the cross between a cold-tolerant cultivar TNG67 (Oryza sativa L., cv. Tainung 67) and a cold-sensitive cultivar TN1 (Oryza sativa L., cv. Taichung Native 1) were developed for QTL analysis. TNG67 and TN1 were treated with low temperature (5℃) for 1, 3, 5 and 7 days and scored 7 days after returning to normal temperature (30/25℃), in order to find the biggest phenotypic difference for chilling tolerance between two parental varieties to augment the statistical power for QTL analysis. The biggest difference of survival rate between TNG67 and TN1 was observed when rice seedlings were treated with low temperature for 5 days. However, the F1 individuals showed significantly different phenotype from both parents. The F1 individuals survived but showed seriously retarded growth after the treatment of 5-days low temperature. Because the phenotype of the F1 individuals was expected in the BC1 mapping population, cold tolerance index and recovery rate, instead of survival rate, were used as phenotypic measurements for QTL mapping. In this study, 71 SSR markers were used to identify quantitative trait loci associated with recovery rate at seedling stage in 109 BC1 lines. A major QTL was identified on chromosome 11, named as qCT11, which explained 41.8％ of the phenotypic variation.
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CHANG-FAN, CHOU, and 周昶汎. "Responses of rice seedling to excess UV-B radiation and comperison between tolerance and susceptible cultiver." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/08720915058137134434.
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碩士<br>國立中興大學<br>農藝學系<br>89<br>The purpose of this study is to explore the physiological and morphological responses of rice seedlings exposed to the excess UV-B irradiation. Further, to screen the UV-B tolerant and susceptible rice cultivar from 186 rice varieties and compare the physiological and morphological responses of UV-B tolerant and susceptible rice cultivars to find the possible mechanism of UV-B tolerance in rice plants.
Three experiments were performed in this study, the first part was a series of morphological and physiological responses were conducted as cultivar TNG-67 V3-seedling exposed to excess UV-B irradiation. Second trial was screening the UV-B tolerant and susceptible rice cultivars. And subsequently, the last part was compared the physiological and morphological responses of tolerant and susceptible rice cultivars to excess UV-B irradiation. Plant materials were planted in growth chamber and treated at V3-seedling. The excess UV-B irradiation treatment was supplied by the UV-B lamps.
Experimental results indicated that exposed to the excess UV-B irradiation affects the growth of rice plant with reduction in plant height, fresh weight, and dry weight, decreased the content of chlorophyll, decreased photosynthetic capacity, damaged stomata structure, and incresed malondialdehyde content and electrolyte conductivity. The enzymatic antioxidants ( superoxide dismutase, ascorbate peroxidase and glutathione reductase ) activity were increased at the first day of UV-B exposure, and then decreased during the treatment period. However, nonenzymatic antioxidants content of ascorbic acid, reduced form glutathione and oxidized form glutathione of rice seedling were increases of the V3-seedling after exposure of excess UV-B irradiation.
As a result of screening the UV-B tolerant and susceptible cultivar of rice, cultivars M202 and Odashiroho were referred to tolerant and susceptible rice cultivar among japonica type rice, as well as the Macan Binong pate and Dular were referred to tolerant and susceptible rice cultivar among indica type. Both tolerant and susceptible rice cultivars expressed damaged under excess UV-B exposure, the tolerant rice cultivars were suffered from little damaged under excess UV-B exposure as compared to susceptible rice cultivars, and the japonica type rice were suffered a less damaged than indica type rice. The activities of enzymatic antioxidants from tolerant rice cultivars were higher than susceptible rice cultivars, and the nonenzymatic antioxidants content of tolerant rice cultivars were larger than those of susceptible rice.
Finally, comparison the injury response and antioxidant activity of rice seedling exposed to excess UV-B irradiation, it is suggested that the UV-B tolerance mechanism of rice not only depend on antioxidant system, the other factors will be involved.
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Jwo, Woei-Shyuan, and 卓緯玄. "Physiological characterizations of salt tolerance at germaination and seedling stages in rice (Oryza sativa L.) Tainung 67 mutants." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/04134491658148755366.
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碩士<br>國立中興大學<br>生命科學院碩士在職專班<br>95<br>Rice (Oryza sativa L. ), one of the most important cereal crops in the world. There are three major cereal crops in the world, namely rice, wheat, and maize and totally offer 50% of the calorie sources to the world population. Soil salinity is a complex and harmful threat faced by plants. High concertrations of salts will suppress crops growth and interfer physiological metabolisms. Rice is a salt-sensitive crop and the soil salinity decreases the yield. This thesis is aimed at the characterizations of physiological responses to salt stress in rice.
Mutants of Tainung 67 ( TNG 67 ) rice variety were screened for salt tolerance at seedling stage. Two mutant strains were successfully identified with ST-099, a salt-tolerant strain, and ST-300, a salt-sensitive strain. Their agricultural characteristics showed no difference in growth. The tolerance to salt of ST-099 (salt-tolerant strain) was the same at germination stage and seedling stage. ST-099 has higher relative water content (RWC) and relative growth rate (RGR) than salt-sensitive strain ST-300 under salt stress. On the other hand, ST-099 is more sensitive to water-deficit stress at seedling stage than at germination stage. The results suggest that the adaptation mechanisms to salt and water-deficit stress are not identical.
Elemental Analyses showed salt-sensitive strain ST-300 had a lower potassium content, a higher sodium content, a higher chlorine content, and a higher Na+/K+ ratio. There was no significant difference in the amount of calcium at initial stage of salt stress suggesting that delay of Ca2+-mediated signaling was a factor contributing to its salt sensitivity. As for salt-tolerant ST-099 strain, it had the lowest sodium content and Na+/K+ ratio. A rapid increase in calcium concentration at initial stage of salt stress was very prominent in this salt-tolerant strain. Furthermore, other evidences leaded us to hypothesize that this strain might be able to use excess Na+ for osmoregulation, and as the result, the rate of decrease in relative water content was much slower in ST-099. Under the same NaCl concentration, the salt-sensitive strain had a higher proline concent, and the salt-tolerant strain accumulated much lower level of proline suggesting proline accumulation is a result of injury caused by salt stress.
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TENG, MIN-GIANG, and 滕民強. "Studies on the stability of^^F1 hybrids derived from special combinations and the comparison of screening method for chilling tolerance of seedling in corn." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/63952467072264979928.
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