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Soltani, Ali. "Improvement of seed germination of Fagus orientalis Lipsky /." Umeå : Dept. of Silviculture, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s275.pdf.
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Taab, Alireza. "Seed dormancy and germination in Solanum nigrum and S. physalifolium as influenced by temperature conditions /." Uppsala : Dept. of Crop Production Ecology, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200949.pdf.
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Chanon, Ann Marie. "Studies on the reproductive capacity of Aesculus parviflora and Aesculus pavia opportunities for their improvement through interspecific hybridization /." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1118692145.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xx, 305 p.; also includes graphics. Includes bibliographical references (p. 278-305). Available online via OhioLINK's ETD Center
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Balcha, Girma. "Seed viability and in vitro culture of Afrocarpus gracilior and germination studies on Ekebergia capensis and Pygeum africanum." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/10712.
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The conditions which prolong viability and the low germination rate of seeds of Afrocarpus gracilior were studied. Different seed lots were stored under various moisture content and temperature combinations. The two seed lots tested had different initial viabilities, probably due to different pre-storage treatments, but generally similar storage requirements to maintain viability at a reasonable level. Tetrazolium tests gave consistently higher viability estimates than germination tests but were well correlated with the latter. Intact seeds were found to have a very low germination rate. However, removal of the seed coat and germination at 30oC resulted in germination rates of up to 80% after 30 days. The seed coat was found to contain a very powerful inhibitor of germination of Triticum seed. Studies were made on the germination of seeds of Ekebergia capensis and Pygeum africanum. Intact seeds of E. capensis germinated at about 52% under optimum conditions and slight damaging of the seed coat halved the germination rate. Intact seeds of P. africanum germinated at about 20% under optimum conditions and slight damaging of the seed coat doubled the germination rate. Shoots of A. gracilior were found to grow well in vitro on hormone free medium but did not produce axillary buds during normal growth and development. However, it was found that decapitation resulted in the formation of axillary buds at or near the top of the shoots which subsequently developed into shoots. Treatment of intact or decapitated shoots with benzyladenine resulted in the initiation of numerous buds but it proved impossible to extend them into shoots. Extending shoots rooted spontaneously on hormone free medium and were also rooted ex vitro in compost under non-sterile conditions and the rooted plants were weaned to greenhouse conditions.
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Shikesho, Saima Dhiginina. "Seed dispersal by black-backed Jackals (Canis mesomelas) and hairy-footed gerbils (Gerbillurus spp.) of !nara (Acanthosicyos horridus) in the central Namib Desert." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/34013.
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This study investigated primary seed dispersal of !nara (Acanthosicyos horridus) by Blackbacked Jackals (Canis mesomelas) and secondary seed dispersal by scatter-hoarding hairyfooted gerbils (Gerbilliscus (Gerbillurus) spp.) in the central Namib Desert. This was accomplished by examining visitation rates and fruit removal of !nara melons, primarily by jackals. In addition, I determined the viability and germination rate of !nara seeds collected from jackal scat. The results indicate that jackals were the dominant species to visit !nara (93.3%) and the only !nara frugivores recorded by camera traps over two !nara fruiting seasons. There was no difference in the viability of ingested seeds and control seeds, but germination rates of ingested !nara seeds were significantly higher (50.4%) than control !nara seeds (34%). This component of the study suggests that Black-backed Jackals are the main primary dispersers of !nara seeds in the central Namib Desert. I furthermore examined secondary seed dispersal by tracking !nara seeds to determine whether scatter-hoarding hairyfooted gerbils were caching or consuming seeds. I recorded the distance moved, depth of seed burial, recovery rate and the habitats in which seeds were buried in three habitat types. Hairyfooted gerbils removed 100% !nara seeds from experimental sites and cached 60.3 % of all the !nara seeds removed. The gerbils frequently retrieved the buried caches within two days (77% of the time) and re-cached them elsewhere. The majority of caches were in the open areas (83%) and only consisted of one (39%) or two seeds (45%). Only 1.7% of the cached seeds were not retrieved by the gerbils during the 30-day observation periods. !Nara seeds were moved an average distance of 29.1±1.6 m and buried at an average depth of 4±0.2 cm. Although there is high probability of cache retrieval, some of the cached seeds survived. As gerbil caches are at favourable locations for plant establishment, and as it is more likely that buried seeds will survive until suitable conditions for germination and seedling establishment, seed dispersal by hairy-footed gerbils is advantageous to !nara plants. Therefore, hairy-footed gerbil species in the central Namib Desert contributed to secondary seed dispersal of !nara. The combined interaction of endozoochory by Black-backed Jackals (Canis mesomelas) and synzoochory by hairy-footed gerbils (Gerbillurus spp.) in dispersing seeds of !nara plants (Acanthosicyos horridus) in the central Namib Desert suggest diplochory is highly likely.
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Silva, Elsa Susana de Sousa Dimas. "Contributo para a caracterização das sementes das espécies endémicas lenhosas dos Açores: Picconia azorica, Prunus azorica, Juniperus brevifolia e Vaccinium cylindraceum." Master's thesis, ISA/UL, 2014. http://hdl.handle.net/10400.5/8227.
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Mestrado em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaThe present work was organized into two sections: the first one assemble all existing information regarding the characterization of four endemic species of the Azores and their propagation techniques; the second presents the results obtained in 2007 and 2012 / 2013 concerning the morphological characterization of the batch of fruit and seeds of these species and their physiological characterization, regarding seed lots’ viability and its germination capacity. It was also tested some techniques to break seed dormancy, having obtained the following results: 1) The removal of the seed coat form the Picconia azorica is enough to induce improvements in their germination rates; 2) In Prunus azorica the germination rates were zero, but the removal of the seed coat may be a methodology to apply in the future; 3) The best germination rates for Juniperus brevifolia where obtained after applying a chemical scarification with H2SO4, for 45 minutes, followed by a cold stratification for 60 days; 4) The seeds of Vaccinium cylindraceum easily lose their ability to germinate due to the moisture reduction and should be sown soon after harvested
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Livingston, Margaret. "Factors influencing germination and establishment of Arizona cottontop, bush muhly, and plains lovegrass in southern Arizona." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186068.
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Germination and establishment was evaluated in Arizona cottontop (Digitaria californica (Benth.) Chase), bush muhly (Muhlenbergia porteri Scribn.) and plains lovegrass (Eragrostis intermedia Hitchc.) from southern Arizona. Germination was determined in different aged seed harvested from native and irrigated plots of various populations. Results indicated variability in germination characteristics of study species that appeared unrelated to afterripening or dormancy. Germination ranged from 62 to 96% for Arizona cottontop, 34 to 99% for plains lovegrass, and 75 to 99% for bush muhly. Bush muhly had highest average velocity of germination (58.0 ± 4.1), followed by plains lovegrass (35.9 ± 1.91), and Arizona cottontop (31.4 ± 1.13). Effects of 3 surface treatments (furrows, gravel, litter) and 2 cultivation treatments on establishment of study species and yellow bluestem (Bothriochloa ischaemum (L.) Keng var. ischaemum) was investigated in the field. Bush muhly did not emerge and plains lovegrass had minimal emergence. Arizona cottontop had similar emergence in cultivated and uncultivated plots whereas yellow bluestem had greater emergence in cultivated plots. Litter promoted greater survival of Arizona cottontop. Lower survival in furrows may have resulted from fewer days with available soil moisture and interference from greater density of non-seeded species. Soil covers appear to positively influence survival rather than emergence. Effect of rainfall distribution on germination was investigated using 2 seed retrieval methods. Arizona cottontop and bush muhly germinated after at least 3 days of available soil moisture. Plains lovegrass seeds did not germinate in the field but retrieved seeds had 83% germination, possibly due to light exposure under laboratory conditions. Another study determined whether species have different density and cover under overstory species compared to open areas. Arizona cottontop had either greater, less, or no differences in density under canopied versus open areas. Cover of Arizona cottontop was greater or similar among canopied and open areas. Plains lovegrass had lower or similar density and cover under canopies than in open areas. Bush muhly had greater density and cover under canopies. Overall, studies suggested that species are easily germinated, but accept relatively narrow ranges of environmental conditions for establishment. Establishment may be enhanced by sowing species when rainfall is consistent, extending available moisture through use of soil covers, or mimicking microsites where a species occurs naturally.
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陳慶讓 and Hing-yeung Chan. "Structural and cytochemical studies on the scutellum and aleuronecellsof oat seeds before and after germination." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207522.
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Haba, Steven R. "Conservation of Begonia germplasm through seeds: characterization of germination and vigor in different species." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420040181.
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Ignácio, Vanessa Leonardo. "Germinação e conservação de sementes de Balfourodendron riedelianum (Engler) Engler." Universidade Estadual do Oeste do Paraná, 2013. http://tede.unioeste.br:8080/tede/handle/tede/1454.
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The growing awareness of society to ecological problems is providing a considerable increase in demand for seeds and seedlings of native species. The Balfourodendron riedelianum (Engler) Engler is a native woody species of economic importance and ecological landscape, popularly known as ivory wood. The purpose of this study was to identify the ideal temperature for germination and determine the seed physiological potential of this species collected from different sources. The objective also their behavior with respect to storage and predict the storage period seeds and determine the constants of the longevity equation. Seeds collected in Marechal Cândido Rondon, Entre Rios do Oeste and Diamonte D'Oeste / PR were studied. For germination evaluation, two temperatures, 25 oC and 20-30 oC constant alternating with a photoperiod of 16-8 hours, and as substrate germitest paper were used. It was stored for 360 days, fruit in two different packaging (bag Kraft paper and glass) and in two different environments (controlled and uncontrolled). The experimental design used was completely randomized. The evaluated variables were: fruit length, percentage of germination, first count of germination, germination velocity index, moisture content, weight of thousand fruit and seedling length. Storage periods were 0, 90, 180, 270 and 360 days after fruit processing. For the development of the equations of longevity it was determined constants that made the equation through regression lines. The germination seeds of Balfourodendron riedelianum (Engler) Engler, was not affected by constant temperature of 25 oC compared with temperatures of 20-30 oC. The seedling length ivory wood was not influenced by temperatures of 25 oC constant and alternating temperature of 20-30 oC, from 90 days of storage. Among provenances, Entre Rios do Oeste stood out from the others to 0 and 360 days when he presented the highest rate of germination. The fruit stored in glass containers in uncontrolled environment and environmental conditions, did not show variations, related to the water content, thus demonstrating the best way to store ivory wood fruit. The mass of a thousand fruits stick ivory were 329.5 g, 585.5 g and 450.0 g for the provenances of Marechal Cândido Rondon, Entre Rios do Oeste and Diamonte D'Oeste, respectively. To seed ivory wood, the constants found to predict longevity were: Ke = 2.8667; Cw = 9.7697 E-013; Ch = 1.3435 E-012 and Cq = 1.1651 E-013. Using the storage conditions with average temperatures of 23 oC or 15 oC, and the ivory wood seeds showing moisture content of 12%, can be stored for up to 2 years. The values of the Pearson correlation between the actual percent germination calculated and the percentage of germination were 73% and 76% for the provenances Entre Rios do Oeste and Diamonte D'Oeste, and 77% and 74% for uncontrolled and controlled environment, respectively
A crescente conscientização da sociedade para os problemas ecológicos vem proporcionando um considerável aumento na demanda por sementes e mudas de espécies nativas. O Balfourodendron riedelianum (Engler) Engler é uma espécie lenhosa nativa, de importância econômica, paisagística e ecológica, popularmente conhecida como pau marfim. Objetivou-se, neste estudo, identificar a temperatura ideal para germinação e determinar o potencial fisiológico de sementes desta espécie, colhidas de diferentes procedências. Objetivou-se também verificar o comportamento das sementes com relação ao armazenamento, predizer o período de armazenamento destas sementes e determinar as constantes da equação de longevidade. Foram estudadas sementes, colhidas em Marechal Cândido Rondon, Entre Rios do Oeste e Diamante D Oeste/PR. Para avaliação da germinação, foram utilizadas duas temperaturas, 25 oC constante e 20-30 oC alternada, com fotoperíodo de 16-8 horas, e como substrato o papel tipo germitest. Armazenou-se, por 360 dias, os frutos em duas diferentes embalagens (saco de papel Kraft e vidro) e em dois diferentes ambientes (controlado e não controlado). O delineamento, utilizado, foi inteiramente casualizado Foram avaliadas as variáveis: comprimento de frutos, massa de mil frutos, porcentagem de germinação, primeira contagem de germinação, índice de velocidade de germinação, grau de umidade e comprimento de plântulas. Os períodos de armazenagem foram: 0, 90, 180, 270 e 360 dias após o beneficiamento dos frutos. Para a elaboração das equações de longevidade determinou-se as constantes que compõem a equação através de curvas de regressão. A germinação das sementes de Balfourodendron riedelianum (Engler) Engler, não sofreu efeito da temperatura constante de 25 oC, quando comparadas com temperaturas alternadas de 20-30 oC. O comprimento das plântulas de pau marfim, não foi influenciado pelas temperaturas de 25 oC constante e temperatura alternada de 20-30 oC, a partir de 90 dias de armazenamento. Entre as procedências, a Entre Rios do Oeste destacou-se das demais aos 0 e 360 dias, quando apresentou os maiores valores de velocidade de germinação. Os frutos, armazenados em embalagens de vidro e em local sem controle das condições ambientais, não apresentaram variações relacionadas ao teor de água, evidenciando, assim, a melhor maneira de armazenar frutos de pau marfim. Os valores da massa de mil frutos de pau marfim foram 329,5 g, 585,5 g e 450,0 g para as procedências Marechal Cândido Rondon, Entre Rios do Oeste e Diamante D Oeste, respectivamente. Para sementes de pau marfim, as constantes encontradas a fim de predizer a longevidade foram: Ke= 2,8667; Cw=9,7697E-013; Ch=1,3435E-012 e Cq=1,1651E-013. Para as condições de armazenamento com temperaturas médias de 23 oC ou de 15 oC, e as sementes de pau marfim apresentando grau de umidade médio de 12%, podem ser armazenadas pelo período de até 2 anos. Os valores da Correlação de Pearson entre a porcentagem de germinação real e a porcentagem de germinação calculada foram 73% e 76%, para as procedências Entre Rios do Oeste e Diamante D Oeste, e 77% e 74%, para ambiente não controlado e ambiente controlado, respectivamente
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Hampstead, Anthony. "Mathematical approaches to seed germination." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/13979/.
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Plant seeds progress through specific stages during germination, from quiescence in the dry state through water uptake, testa rupture and finally endosperm rupture. The stages of seed germination are fairly well classified but the underlying biochemical and mechanical processes are unknown. The ability to control a seeds progression through the stages of germination has implications on farming efficiency and so the following thesis explores Arabidopsis thaliana and Lepidium sativum seeds during the germination process. A systematic approach to analysing the shape of cells within the radicle (embryonic root tissue) is developed, using confocal imaging, in order to characterise the shape of cells in the different tissues of the radicle. The cell shape approximations are not refined enough to characterise the different cell tissues. With more data, this approach would hope to find the region in which cells alter through the germination process. Change in the activity of cell wall modifying enzymes within the endosperm, that surrounds the emerging embryo, is a key part of the germination process and temporally and spatially defined high resolution transcriptomics data-sets are available to inform models. Through the course of this thesis, biochemical networks are developed, with ordinary and partial differential equation models being constructed and analysed. The models highlight elements for further investigation as well as differences between the two species considered. The mathematical models, along with data from biomechanical experiments on the endosperm, inform discussion on how the cell wall biochemistry of a cell wall alters the cell wall properties. These discussions focus on cell wall permeability, extensibility and the final cell separation event associated with germination. From the considered proteins, polygalacturonase and pectin lyase arise as the only viable candidates to cause the cell separation event with the model framework.
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Ma, Liuyin. "THE ROLE OF POLYADENYLATION IN SEED GERMINATION." UKnowledge, 2013. http://uknowledge.uky.edu/pss_etds/47.
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Seed germination has many impacts on the uses of seeds, and is an important subject for study. Seed germination is regulated at both transcriptional and post-transcriptional levels. Therefore, it is important to study how polyadenylation regulates gene expression during seed germination. To this end, a modified Illumina GAIIx sequencing protocol (described in Chapter Two) was developed that allows deep coverage of poly(A) site position and distribution.
Alternative polyadenylation (APA) regulates gene expression by choosing one potential poly(A) site on a precursor RNA consequentially shortening/lengthening the mRNA relative to other possible sites. To further explore this phenomenon, genes affected by APA during seed germination and other developmental stages were identified (Chapter Three). These genes were categorized based on the location of poly(A) sites. Several genes were chosen to demonstrate how APA, especially that occurring in the coding regions and 5’ untranslated regions, might down regulate gene expression by generating truncated transcripts.
In animal oocytes, maternally-derived mRNAs are stored with short poly(A) tails and reactivated by the cytoplasmic polyadenylation complex. It has been reported that seeds also contain stored mRNAs. Moreover, germination and its completion are less sensitive to de novo transcription inhibitors than to poly(A) polymerase inhibitors. Together, these considerations suggest that stored RNA without or with a short poly(A) tail (stored, unadenylated RNA) may be present in dry seed and function in seed germination upon reactivation by cytoplasmic polyadenylation. To further explore this, in Chapter Four, mRNA polyadenylation was studied through the course of germination using a combination of transcriptional inhibitors and the modified sequencing protocol described in Chapter Two. 273 putative stored, unadenylated RNAs were identified. Gene ontology analysis revealed that genes whose products are involved in translation are overrepresented; these genes encode 21 60S- and 10 40S-ribosomal proteins. These results indicate that transcripts whose products are involved in translation might be a major component of the stored, unadenylated RNA pool and, more importantly, translation might be the first cellular process to be activated during seed germination.
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Kandolo, Sadiki Delphin. "Effect of fungicide seed treatments on germination and vigour of maize seed." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/29544.
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Fungicides have been developed to protect plants against diseases and pests, which cause serious problems such as the loss of germination and vigour. The aim of this study was to test the germination and vigour of maize (Zea mays L.) seeds treated with several fungicides Apron® Star 42 WS (difenoconazole, thiamethoxam, and metalaxyl-m), Apron® XL (mefenoxam), Celest® XL (fludioxonil, mefenoxam) and thiram in the laboratory. In the greenhouse, the efficacy of fungicide treatment was evaluated in soil inoculated with Fusarium graminearum. The control consisted of untreated seeds. Germination and vigour were evaluated according to the International Seed Testing Association (1ST A) rules. The results from the standard gennination tests showed that all the fungicide treated seeds did not differ to the untreated control. The conductivity of solute leakage was read following slow and fast imbibition. Maize seeds treated with Apron® Star 42 WS, Celest® XL, Apron® XL and thiram improved or maintain vigour, which was indicated by a reduced or equivalent solute leakage following fast imbibition when compared with the untreated control. The good performance of fungicide treated seed expressed during conductivity test after fast imbibition correlated with the tetrazolium. All the fungicide treated seeds maintained the same viability as the untreated control following fast imbibition. After 6 h after fast imbibition, Apron® Star 42 WS, Celest® XL and Apron® XL treated seeds maintained similar germination percentages when compared to the untreated control with the exception of thiram treated seeds that exhibited a decline in seed viability. There was reduction in vigour in all the fungicide treated seeds fo llowing 24 and 40 h fast imbibition as illustrated by the reduction in germination percentage below the acceptable level (70%) when compared with the untreated control. The greenhouse study showed that all the fungicide treated seeds maintained the same emergence percentage in both inoculated and uninoculated soil with the exception of thiram treated seeds, where emergence improved in inoculated soil when compared to the untreated control. Apron® Star 42 WS and Celest® XL reduced the disease caused by F. graminearum in the inoculated soil. This study also revealed that the application of Apron® Star 42 WS, Celest® XL and thiram to seeds improved both the shoot and root dry mass of plants in the inoculated soil.Dissertation (MInstAgrar)--University of Pretoria, 2011.
Microbiology and Plant Pathology
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Zaman, S., S. Padmesh, and H. Tawfiq. "Effect of Pre-germination Treatments on Seed Germination of Helianthemum lippii (L.) Dum.Cours." University of Arizona (Tucson, AZ), 2009. http://hdl.handle.net/10150/556666.
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Helianthemum lippii (L.) Dum. Cours. is a perennial shrubby plant 10-45 cm tall that belongs to the family Cistaceae. The effects of pretreatments on germination of Helianthemum lippii provide information regarding germination requirements of this species, which could be used for conservation studies. Five different pretreatment were applied to enhance seed germination. Scarification followed by germination at 6 different constant temperatures (10, 15, 20, 25, 30 and 35°C) with continuous light or dark, Scarification followed by GA3 soaking (100, 250,500,750 and 1000 ppm), Heat and moist stratification (only intact seeds), KNO₃ and H₃BO₃ soaking (only intact seeds). The results obtained from this study indicate that germination in H. lippii was promoted by scarification. Scarification of seeds resulted in high germination while increasing germination temperature (35°C) decreased the germination of scarified seeds. Exposure to light and dark had no effect on germination. Heat stratification, cold stratification, KNO₃ and H₃BO₃ treatments were ineffective in increasing germination of H.lippii seeds. Scarification yielded maximum germination without soaking in GA₃ It increased the germination of Helianthemum lippii seeds from 1 to 99%. Increase in GA₃ concentration decreased the germination of this species. Scarification succeeded in breaking dormancy of H.lippii seeds suggesting that this species exhibits seed coat dormancy and in nature it may happen due to the abrasion of seed coat by sand particles or other biotic and abiotic factors.
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Omami, Elizabeth Nabwile. "Amaranthus retroflexus seed dormancy and germination responses to environmental factors and chemical stimulants /." [S.l. : s.n.], 1993. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030603.091907/index.html.
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Sumugat, Mae Rose S. "Glutathione Dynamics in Arabidopsis Seed Development and Germination." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/36420.
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Seed desiccation and germination have great potential for oxidative stress. Glutathione, one of the most abundant antioxidants in plant cells, is a crucial to the plant's defense mechanisms. To better understand glutathione's responses during these two stages, we examined its dynamics in wildtype Arabidopsis seeds and in a transgenic line containing an antisense glutathione reductase2 (anGR2) cDNA insert. Seeds from the two genotypes were compared morphologically. Glutathione levels in maturing and germinating seeds were measured by HPLC, and GR activity by native PAGE. Cytosolic glutathione was measured in situ by confocal laser scanning microscopy. Stress in the form of natural and accelerated ageing, and germination at high and low temperature and at low water potential was applied to both WT and anGR2 seeds to test vigor. Results show similar glutathione levels and GR activity (except during late imbibition) in WT and anGR2. In both genotypes, GSH/GSSG ratio increased and GR activity decreased during seed maturation. During imbibition, the glutathione pool becomes very reduced (<1% GSSG) and in WT seeds, GSH levels increase mostly by GSSG recycling. Cytosolic GSH in embryonic epidermal cells was estimated to be 1.1-1.6 mM. AnGR2 seeds aged faster, and were less tolerant of heat and drought stress than WT. Accumulation of glutathione during maturation indicated that glutathione is a major antioxidant in the seed during storage. Changes in GSH levels during imbibition coincided with ROS production during radicle protrusion. Under stress conditions, anGR2 seeds showed lower vigor, indicating perturbations in the ROS scavenging systems particularly GR2.Master of Science
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Kyereh, Boateng. "Seed phenology and germination of Ghanaian forest trees." Thesis, University of Aberdeen, 1994. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU068828.
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Seed production and germination of some timber tree species were studied in Ghana for possible prediction of seed yield and natural regeneration. Seed phenology in 13 species was monitored for two years, using permanent seed traps in two forest sites. Seed germination tests were conducted in neutral, green shade and dark in shade houses for 20 species. In the forest, germination was tested in forest gaps receiving different irradiances. Fruiting frequency ranged from twice in each year to supra-annual fruiting. Fruiting periods for species were consistent between years. Fruiting synchrony was higher among individuals of a population than between sites for the same species. Fecundity differed between years for the majority of species and between sites for species common to both sites. Premature fruit abscission was quite common. Maximum seed weight and percentage germination occurred during peak fall of mature seeds. Seeds of the majority of species germinated equally in light and dark and also in neutral and low red: far red ratio. These included some species previously classified as pioneers. In the forest germination was depressed in a large clearing for the majority of species. The use of photoblastic germination alone to define pioneers leads to a smaller group of pioneer species than is presently recognised. Large gaps due to logging may discourage natural regeneration.
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St, Hilaire Rolston. "Seed Coat Treatments Influence Germination of Taxodium mucronatum." University of Arizona (Tucson, AZ), 2015. http://hdl.handle.net/10150/554341.
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The range of Taxodium mucronatum Ten. (Mexican bald cypress) is declining rapidly, yet relatively little is known about the propagation of this valuable ornamental tree. The objective of this study was to determine whether seed coat treatments could enhance the germination of Mexican bald cypress. Seeds of Mexican bald cypress were collected from Las Cruces and the Gila National Forest, New Mexico. In one experiment, seed coats were knicked or left intact, then germinated on moist filter paper or flooded with water. In another experiment, seed coats from the Las Cruces provenance were treated with sulfuric acid, knicked, left intact, or removed (excised embryos) and germinated on moist filter paper. Knicked and moist seeds had a greater mean cumulative germination percentage (13.5 %) than intact and flooded seeds (4.2 %). Final germination percentage of the Las Cruces source was similar among knicked seeds, intact seeds, and excised embryos, but intact seeds took a longer time (15 days) to reach 50% of final germination percentage than did excised embryos (10 days) and knicked seeds (8 days). Seeds treated with sulfuric did not germinate. Results indicate seed coat pretreatments are needed to release physical dormancy and promote efficient germination of Mexican bald cypress.
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Xia, Qiong. "Molecular aspects of temperature regulation of sunflower seed dormancy." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066629/document.
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La graine est le produit de la reproduction sexuée chez les Angiospermes. Elle assure la survie et la dispersion de l'espèce. La germination des graines est la première étape de la croissance des plantes. La transition entre l'état de dormance des graines et leur germination est une étape clef dans le cycle de vie des plantes qui a des conséquences écologique et commerciale. Depuis plusieurs décennies, de nombreux facteurs de l'environnement ont été étudiés pour leurs implications et leurs conséquences dans le processus de dormance et de germination des graines. Les études sur la réponse des semences aux changements de température en liens avec le réchauffement climatique ont un intérêt primordial. Le but de ce travail a été d'étudier la régulation de la dormance et de la germination des graines de tournesol par la température. Une analyse protéomique et un profilage enzymatique ont été réalisés afin de mieux comprendre la régulation du métabolisme pendant la levée de dormance par la température. L'utilisation d'approches moléculaires et cytologiques, nous ont permis d'appréhender l'interaction entre la température et les phytohormones impliquées dans ce processus. Nos résultats ont révélé le rôle joué par la température comme facteur externe affectant la dormance et la germination des graines en agissant d'une part sur le métabolisme et d'autre part sur la quantité et la localisation cellulaire des principales hormones endogènesA seed is the product of sexual reproduction and the means by which the new individual is dispersed by angiosperms. Seed germination being the first step of plant establishment, the ultimate role of the transition between seed dormancy and germination during plant lifecycle is an important ecological and commercial trait. Last several decades, several environment factors have been reviewed to strongly effect the process of seed dormancy and germination. However, studies about seed response to temperature change are acute with the global warming. The aim of this work was to investigate temperature regulation of dormancy and germination in sunflower seeds. Proteomic analysis and enzyme profiling have been used to study metabolism regulation during seed dormancy release by temperature. Moreover, using molecular and cytological approaches, we investigate the interaction between temperature and phytohormones involved in this process. Our results revealed that temperature as an external factor to effect seed dormancy and germination by affecting, in one hand, the metabolism, and in the other hand the level and localization of major endogenous hormones
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Zhou, Dongfang. "Seed Germination Performance and Seed Coat Mucilage Production of Sweet Basil (Ocimum basilicum L.)." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/49553.
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Sweet basil (Ocimum basilicum L.) is a warm season herb usually propagated from seeds. Establishment of basil is difficult as seed germination may be limited, particularly during field seeding at cold soil temperatures. The germination of six cultivars (\'Italian Large Leaf\', \'Italian Large Leaf\' 35X, \'Nufar\', \'Genovese\', \'Genovese Compact Improved\' and \'Aroma 2\') of sweet basil seeds were tested on a one dimensional thermo-gradient table over temperatures ranging from 0 to 50"C. At temperatures below 20"C, germination among cultivars was more variable and the mean time to germination (MTG) increased to greater than 25 days for some cultivars. Germination declined sharply and had a sudden termination at high temperatures above 40"C for all six cultivars. There were statistical differences among the cultivar base temperatures, which ranged between 10.1 and 13.3"C. The optimal and ceiling temperatures for germination were similar and did not differ statistically among the cultivars compared in this study. The average optimal temperature for all cultivars was 35 ± 0"C, while the average ceiling temperature was 43 ± 1.3"C. Stored seeds (> 5 years) had lower seed vigor and lower germination percentage, also lower ceiling temperature compared with the fresh seeds of the same cultivar (\'Italian Large Leaf\'), but the base temperatures were the same for both new and old seeds.
Sweet basil (Ocimum basilicum L.) seeds produce a thick layer of mucilage around the pericarp within minutes after hydration. Mucilage is most prevalent among plant species adapted to surviving in arid sandy soils, though its significance in determining ecological fitness is unclear. The mucilage produced by seeds is reported to be composed of cell-wall polysaccharides that are deposited in testa pericarp cells during development. In this study, sweet basil seeds were examined using light and environmental scanning electron microscopy. The mucilage of basil seeds is held together by columnar structures that unfolded from the pericarp and helped hold and stabilize the mucilage to the outer surface. The mucilage was removed using diluted hydrochloric acid to compare performance of seeds with and without mucilage. Mucilage removal did not inhibit seed germination under ideal laboratory conditions but decreased the water content of seeds significantly. The water content of intact seeds was almost 4 times greater than seeds without mucilage. Mucilage enabled seeds cling to an incline board set to a steeper angle than seeds without mucilage. The fully hydrated seeds approached zero water potential, so the mucilage did not prevent seeds from fully hydrating. Soil (media) germination testing showed the seeds with mucilage had higher germination percentage than the seed without mucilage on several different types of media. Seeds with mucilage also had higher survival percentages after 10 days on different types of media. Basil seeds mucilage acts as a reservoir to hold loosely bound water at high water potential so it is available for seed germination and early seedling development.Master of Science
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Nolan, Daryl Guy. "Seed germination characteristics of Centaurea diffusa and C. Maculosa." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27605.
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The problematic reinfestation of chemically-treated sites by diffuse and spotted knapweed {Centaurea diffusa and C. maculosa) is thought to occur from dormant seeds in the soil. This study confirmed that reserves of dormant seeds are present in the soil of infested sites, although greater numbers of seeds were recovered from senesced plants. Knapweed plants produce both non-dormant and dormant seeds (germination polymorphism), the relative proportions of which vary between individual plants within a site, as well as between bulk samples collected from different sites. Two types of dormant seeds were identified. Dormancy of some seeds was broken by exposure to red light ('light-sensitive seeds'). Light-sensitivity was evident at 10, 15, 20, 25, and 30°C. Germination in light-sensitive seeds was shown to be mediated by phytochrome. A lesser number of dormant seeds failed to respond to red light ('light-insensitive seeds').
Dry after-ripening released dormancy in both light-sensitive and light-insensitive seeds. However, no apparent loss of dormancy from after-ripening occurred when the relative humidity was too low or too high. At the highest relative humidity level tested (90.7%), dormancy was induced in some seeds while other seeds died. Dormancy was also induced when imbibed seeds were incubated in darkness at 25, 30, 35, and 40°C for 5 days. Dormancy induction was greatly enhanced by incubating submerged seeds in de-oxygenated water (anaerobiosis). However, some seeds died when incubated anaerobically for 5 days. Dormancy was broken in a small percentage of dormant seeds by incubation in a 10 mM solution of potassium nitrate or potassium nitrite; 100 mM potassium nitrite killed most seeds. Gibberellic acid was a much stronger germination stimulant. Some dormant seeds germinated at 25 °C if they were previously chilled at 3°C.
To compare laboratory findings with field germination behaviour, seeds from two samples of each species were buried to a depth of about 3 cm in mesh packets during November, April and August near Salmon Arm, B.C. Seeds exhibiting higher levels of germination in darkness in vitro also germinated to higher levels in situ when burial occurred in November. However, burial in April and August led to lower germination levels in situ. Light sensitivity was still prominent following 17 months of burial. Most of the decline in viable seed numbers during burial were attributable to in situ germination. Theoretical discussions of the source of germination polymorphism in knapweed seeds, the importance of light to field germination and seedling mortality, and a potential strategy for controlling these weeds are presented.Land and Food Systems, Faculty of
Graduate
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Jorge, Marcal Henrique Amici. "GERMINATION AND CHARACTERIZATION OF GUAYULE (Parthenium argentatum GRAY) SEED." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1247%5F1%5Fm.pdf&type=application/pdf.
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Levesque-Tremblay, Gabriel. "Pectin methyl esterification functions in seed development and germination." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46351.
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Dzomeku, Israel K. "Modelling seed dormancy, germination and emergence of Striga hermonthica." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252261.
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Barros, Galvão Thiago. "Regulation of seed dormancy and germination in Arabidopsis thaliana." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/15593/.
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Seed germination is one of the most important developmental steps in the life cycle of a higher plant. Because of this, seed producing plants have evolved mechanisms, such as dormancy, that time germination based on environmental cues. The present study uses Arabidopsis thaliana as a model to address questions about seed dormancy and germination. Three different lines of investigation were followed. The first involved an investigation of how light quality regulates phytohormones in order to control germination. This identified a light-dependent mechanism that differentially regulates expression of the ALLENE OXIDE SYNTHASE and OXOPHYTODIENOATE-REDUCTASE 3 genes resulting in accumulation of cis-12-oxo-phytodienoic acid (cis-OPDA) and repression of seed germination under FR conditions. The second line of investigation involved a re- examination of the role of the ABSCISIC ACID INSENSITIVE (ABI) 5 and ABI4 transcription factors in regulating seed germination and oil mobilization respectively. The study found that abscisic acid (ABA) is able to block testa rupture in nicked seeds and this involves the ABI5, but not the ABI4, transcription factor. Furthermore, it was found that ABI4 is involved in the repression of ABA and cis-OPDA biosynthesis in a light- dependent manner, but has only a minor role in regulating oil mobilization in seeds. The third line of investigation focused on the regulation of dormancy during after-ripening and found that changes in phytohormone levels over an extended period can account for changes in dormancy state.
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Brits, Gert Johannes. "Ecophysiology of Leucospermum R. Br. seed germination in fynbos." Thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/26071.
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Bond, Laureanne Marie Wright Amy Noelle Guertal Elizabeth A. "Seed germination and growth requirements of selected wildflower species." Auburn, Ala., 2010. http://hdl.handle.net/10415/2042.
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Dobrenz, Albert K., Jeffrey C. Silvertooth, and Jill Martin. "Germination and Respiration of Cotton Seed Produced in Arizona." College of Agriculture, University of Arizona (Tucson, AZ), 1993. http://hdl.handle.net/10150/209585.
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The germination percentage and seedling respiration were evaluated on 11 cultivars of Cotton produced in Arizona. Respiration rates of 5-day old seedlings ranged from 6.0 to 16.9 mg /g⁻¹ hr⁻¹ for DP -5690 and KC-311, respectively. Germination percentage ranged from 31 to 87% for KC-311 and DP-51, respectively. A significant negative correlation (r = -.90) between respiration rates and the germination percentage indicates that seed quality is closely associated with early seedling metabolic rates.
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Palzkill, D. A., L. DePaul, and C. Sivilli. "Seed Germination Response of Penstemon spp. To Gibberellic Acid." College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/215861.
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Treatment of seed with gibberellic acid (GA) resulted in significant increases in germination percent for Penstemon ambiguous, P. barbatus, P. eatoni, P. palmeri, P. parryi. P. pseudospectabilis, P. secundiflorus, and P. strictus in one or both of two experiments which were conducted. Germination of several other species increased with GA treatment, but differences were not significant.
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Harding, Kourtney T. "Sclerocactus wetlandicus: Habitat Characterization, Seed Germination and Mycorrhizal Analysis." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6497.
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The Uinta Basin hookless cactus (Sclerocactus wetlandicus) is a threatened species native to Eastern Utah. The cactus is found in a landscape highly disturbed by non-renewable energy production. To understand the environmental conditions that support natural growth of this cactus, we asked whether plant communities differed in the undisturbed areas where the cactus is and is not found. We then compared undisturbed communities to those found on disturbed areas such as reclaimed well pads. Plant community characterization was accomplished with the line-point intercept method, and data were analyzed using Non-Metric Multidimensional Scaling. There was no significant difference in occupied and unoccupied undisturbed plant communities; S. wetlandicus associates with the common vegetation found in the study area. In contract, plant communities on the well pads were significantly different from those present in undisturbed locations. The disturbed areas were dominated by non-native weedy species and bare soil, thus differing from undisturbed habitats that contained higher relative vegetation cover and a mix of species from all functional groups both native and non-native.
To help restore this threatened cactus in disturbed habitats as well as prevent future extinction, we developed and tested a protocol for cactus seed germination in the greenhouse and successfully produced seedlings with a ~75% germination rate. Additionally, an important factor contributing to the successful growth of this threatened cactus is the presence of arbuscular mycorrhizal fungi (AMF). By extracting the DNA from root samples of wild cacti we were able to identify the presence of AMF from the families Glomeraceae and Claroideoglomeraceae representing three genera: Rhizophagus, Glomus, and Claroideoglomus. Sequences closest to Rhizophagus irregularis were identified from multiple root samples. Cactus seedlings may be inoculated with the fungi to promote their growth and ultimately their survival in the wild. Our study indicates that because S. wetlandicus is part of the common plant community of the study area and the well pads are vastly different from the common plant community, disturbed areas should be reclaimed in a way that better resembles undisturbed habitats to increase the likelihood that the newly planted cacti can thrive.
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Guerin, Jennifer Ross. "Endopeptidases in barley seed and their action during germination." Adelaide Thesis (Ph.D.)--University of Adelaide, Department of Plant Science, 1993. http://hdl.handle.net/2440/21658.
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Guerin, Jennifer Ross. "Endopeptidases in barley seed and their action during germination." Thesis, Adelaide Thesis (Ph.D.)--University of Adelaide, Department of Plant Science, 1993. http://hdl.handle.net/2440/21658.
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Benzel, Katie Rebecca. "Defoliation effects on Spotted Knapweed seed production and viability." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/benzel/BenzelK0508.pdf.
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Spotted knapweed (Centaurea stoebe L.) is a deeply taprooted perennial forb infesting millions of hectares of rangeland in western North America. Spotted knapweed forms large monocultures, which lowers plant diversity, reduces livestock and wildlife forage, and increases surface water runoff and sediment yield. It can produce 5,000-40,000 seeds m-2 year-1, and often produces new flowers after prescribed sheep grazing or mowing defoliates spotted knapweed plants during the bolting or flowering stage. Research has yet to determine if new flowers produced following spring/summer defoliation produce viable seeds by the end of the growing season. The purpose of this 2-year study was to determine the appropriate timing(s) or combination(s) of timings of defoliation on spotted knapweed to reduce viable seed production. Ten spotted knapweed plants, located on spotted knapweed-infested rangeland in west-central Montana, were hand-clipped for each of the following treatments: 1) 35-40% relative utilization of above-ground biomass when plants were in the bolting stage; 2) 100% of buds removed at late-bud/early-flowering stage; 3) 100% of flowers removed at full-flowering stage; 4) Treatment 1+Treatment 2; 5) Treatment 1+Treatment 3; 6) Treatment 2+Treatment 3; 7) Treatment 1+Treatment 2+Treatment 3; and 8) unclipped control. The number of buds/flowerheads per plant, number of seeds per plant, percent viability of seeds, and number of viable seeds per plant were determined when seeds were in the well-developed stage, but seedhead bracts were still tightly closed (mid-August through September). Clipping at any timing or combination of timings reduced the number of buds/flowerheads per plant (P < 0.01), number of seeds per plant (P < 0.01), percent viability of seeds (P < 0.01), and number of viable seeds per plant (P < 0.01) both years compared with the unclipped control. Clipping during the bolting stage reduced the number of viable seeds by nearly 90% compared with no clipping. Clipping during the late-bud/early-flower or full-flower stage reduced the number of viable seeds by nearly 100% compared with no clipping. Defoliation of spotted knapweed via prescribed sheep grazing or mowing in summer should effectively suppress viable seed production of spotted knapweed.
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Wood, Christopher. "Oxidative stress and seed survival." Thesis, Abertay University, 1998. https://rke.abertay.ac.uk/en/studentTheses/79d28b74-9210-4ebd-a3b8-66a610bd8c87.
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Free radical and aldehydic breakdown product content were determined, by EPR and UV / visible spectroscopy, primarily in intermediate (desiccation tolerant) seeds of Carica papaya L. (Papaya) and recalcitrant (desiccation intolerant) seeds of Aesculus hippocastanum L. (Horse chestnut), but also in other species covering a range of desiccation tolerances, with a view to determining the role of oxidative stress as a diagnostic marker for desiccation tolerance. Axes of non-senescent highly viable recalcitrant seeds of horse chestnut were metabolically active, contained products of lipid peroxidation, displayed low levels of enzymatic protection against activated oxygen and peroxides, and a two-peak free radical EPR signal. During fully hydrated storage at 16 °C for up to 18 months, seeds exhibited, sequentially, an increase in germination rate, a transient increase in intensities of both the low field and high field EPR peaks, a significant increase in membrane leakage and decrease in seed viability, germination rate, and SOD and peroxidase activities. Drying 'unstored' seeds below and embryonic axis moisture content of 40 to 50 % initiated viability loss. At < 25 % moisture content all axes were inviable and displayed a 2- to 4-fold increase in solute leakage, lipid peroxidation products and the low field EPR signal. Seed desiccation sensitivity increased with hydrated storage. The accumulation of lipid peroxidation products and free radicals on drying generally occurred to a greater extent, or at a higher moisture content, than observed with unstored seeds. The results indicate a mediating role for oxidative stress in recalcitrant seed viability loss which is differentially expressed during hydrated, 'natural' ageing and desiccation. Similar trends were seen in other recalcitrant species with the increase in lipid peroxidation products occurring around the point of viability loss. However the study of a more orthodox species (papaya) revealed no such trends.
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Liebenberg, Louis Christian Cronje. "Studies on the seed-setting and on the germination of the seed of indigenous grasses with particular reference to methods for overcoming delayed germination." Pretoria : [s.n.], 1990. http://upetd.up.ac.za/thesis/available/etd-06042007-134353.
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McElhannon, Laura Michelle Waters Luther. "Enhancement of seed germination and seedling growth of Lenten rose." Auburn, Ala., 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Horticulture/Thesis/Moore_Laura_47.pdf.
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Ali, Abdou-Djalilou. "Prediction of tomato seed germination from images with deep learning." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24666/.
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Assessment of seed germination is an essential task for seed researchers to measure the quality and performance of seeds not only to achieve high productivity but also for economic growth. In fact, knowing in advance the germination rate of the seeds can give farmers a better idea of how much their fields will produce. The seeds assessment can be done before or after the experiment. In the after-experiment assessment, trained analysts evaluate the seed germination by counting the seeds which present radicles or leaves emanating from them. However, the counting process done by analysts is cumbersome, error-prone, and time-consuming. Hence, machine learning-based methods have been proposed for the situation in which the assessment of seeds is done after experiment, to determine whether a seed germinated or not. Assessment of the seeds done before or after the experiment via model-based approach present many advantages: it is fast, more repeatable, and more accurate. In this thesis, we will consider the situation where the assessment of seeds is performed instead before the start of the experiment. That is, the proposed model will try to predict the seeds that are going to germinate and those that are not going to germinate before they will be placed in a chamber under proper growing condition for seven days. Prediction before the experiment holds the potential to further reduce the time required to select the seeds that are going to germinate and to let only valid seeds proceed to use the germination equipment. Therefore, in this thesis, we study the performance of a model-based approach that uses modern convolutional neural networks to predict the germination of tomato seeds, that is, whether a seed will germinate or not after it will have spent some period in the controlled environment for growing purposes.
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Allison, Edwin. "Effects of seed adjuvants on germination and development of onions." Thesis, Cape Technikon, 2001. http://hdl.handle.net/20.500.11838/2000.
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Thesis (MTech (Agriculture))--Cape Technikon, 2001.Onion seeds (cultivar Caledon Globe), and soil into which the seedlings were planted, were treated with various adjuvants including fungicides, a seed disinfectant and a soil sterilant, as well as soil-applied growth stimulants to determine the effect of these on germination of seed, the growth of plants and the storage life of onions obtained. Three sets of germination trials were undertaken in petri dishes, and sets of seed was also sown in deep seed trays. A trial planting was made and the crop graded and stored. Seed was also sown in pots in soil obtained from a commercial undertaking where poor germination had been obtained. A portion of this soil was pasteurised and a portion inoculated with Fusarium spp. Growth of these seedlings was then followed by re-sowing in the same pots using seed of additional cultivars.
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Gallagher, Robert Sean. "Ecophysiological aspects of phytochrome-mediated germination in soil seed banks /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487933648650464.
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Burgess, Tyler Lynne. "Seed Germination Studies of Southern Seaoats (Uniola paniculata)." NCSU, 2002. http://www.lib.ncsu.edu/etd/public/etd-138080102270/etd.pdf.
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Morgan, Michael John. "Increasing seed germination and quantifying drought tolerance of Bursera graveolens." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041327.
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Kendall, Sarah. "Temperature regulation of seed dormancy and germination in Arabidopsis thaliana." Thesis, University of York, 2012. http://etheses.whiterose.ac.uk/3109/.
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The environmental regulation of seed dormancy and germination by temperature is an important process which allows the environmental conditions experienced by plants in the following generation to be controlled. Coping with temperature effects during seed maturation is essential for the consistent production of high quality seeds, but currently temperature signalling pathways in seeds are poorly understood. Previous work has shown that temperature during seed maturation regulates the levels of dormancy which are induced in the seed, although a mechanism for this pathway is currently unknown. Low temperature during imbibition promotes germination and although this is known to involve alterations to GA metabolism, again a mechanism is missing. Therefore, the aim of this study was to identify components of the mechanisms which regulate the temperature control of dormancy and germination in the model plant Arabidopsis thaliana. Cool and warm seed maturation temperatures induce high and low levels of dormancy respectively in Arabidopsis. These changes to dormancy levels are coupled with altered ABA and GA levels and gene expression controlling hormone synthesis and breakdown. Changes in maturation temperature do not appear to be linked to altered seed coat morphology or embryo development. During testing of cold-response mutants for dormancy phenotypes the expression of CBFs, a group of transcription factors which were characterised through the study of cold acclimation, was found to be necessary for dormancy. CBF RNAi and mutant seeds display reduced dormancy when matured at low temperature. However, the expression of CBFs is not promoted by exposure to low temperature in seeds, suggesting that this is not an important mechanism for the temperature control of dormancy. More strikingly, the E3 ligase HOS1 is absolutely required for high dormancy levels in response to low maturation temperature. hos1 mutants show a complete loss of dormancy when matured at any temperature and this phenotype is maternally inherited. The germination of hos1 seeds in the presence of PAC or ABA does not differ from wild-type, thus suggesting that sensitivity to GA and ABA is not altered in these seeds. However, levels of GA are increased in hos1 mutant seeds, which could be important for the reduced dormancy phenotype. The expression of TT genes, which are responsible for the accumulation of anthocyanidins in the seed coat, is downregulated in hos1 mutants and so could be involved in the regulation of dormancy by HOS1. Therefore; HOS1 defines a novel essential maternal pathway that regulates dormancy levels which involves the regulation of GA metabolism. A forward genetic screen identified a number of cold stratification insensitive (cosi) mutants. A thorough characterisation of these mutants revealed interesting phenotypes, but phenotypic variation and a lack of robust segregation data meant that the cosi mutants were not mapped.
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Just, Michael. "Seed morphology, dormancy and germination of South-West Australian Ericaceae." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2018. https://ro.ecu.edu.au/theses/2051.
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The Ericaceae in South West Australia contains species with difficult to germinate seeds, including many species with deep intractable dormancy. A better understanding of seed biology and species specific dormancy, and germination mechanisms is required to overcome these difficulties. Land clearing, salinity and disease has resulted in over 125 species within 15 genera being listed as rare, highly restricted, threatened and endangered (Western Australian Herbarium 1998–). The present study examined the seed biology of eight species of Ericaceae native to Western Australia, exploring fruit and seed morphology, dormancy and germination. Cold and warm stratification was used in combination with gibberellic acid to classify dormancy. Among the two distinct fruit types that occur within the Ericaceae separate patterns of dormancy were found. Seeds held within a dehiscent capsule were found to possess non-deep and intermediate physiological dormancy whilst those within an indehiscent drupe possessed physiological and morphophysiological dormancy. Oxygen and nitric oxide enriched atmospheres, removal of seeds from endocarps and propagation from cuttings provided potential avenues for the propagation of study species.
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PETROLLINI, Elisa. "Medicago marina (L.) seed: unravelling mechanisms controlling germination and dormancy." Doctoral thesis, Università degli studi del Molise, 2012. http://hdl.handle.net/11695/66384.
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L’obiettivo generale di questo lavoro di tesi è studiare i complessi e poco conosciuti meccanismi che regolano la dormienza e la germinazione del seme di Medicago marina (L.), una specie mediterranea presente sulle coste dell’intera penisola italiana e che si è adattata a vivere in habitat specializzati come le dune.
I semi di questa specie sono caratterizzati da una forte dormienza che ne impedisce la germinazione e i risultati ottenuti durante il primo periodo del corso di dottorato, sono stati recentemente pubblicati (Scippa et al., 2011). I meccanismi che regolano dormienza/germinazione e la risposta agli stress dei semi di questa specie, sono stati studiati attraverso analisi fisiologiche e di proteomica. Fra i pretrattamenti utilizzati (scarificazione meccanica, congelamento a -20°C e riscaldamento a 100°C per un’ora), la scarificazione e il congelamento sono stati più efficaci nella rimozione della condizione di dormienza. Il ruolo dell’acido abscissico (ABA) è stato studiato attraverso un dosaggio immunoenzimatico (ELISA) che ha permesso di determinarne la concentrazione nei semi trattati, germinati e non germinati (semi maturi utilizzati come controllo). Fra tutti, la maggiore concentrazione di ABA è stata riscontrata nei semi sottoposti a riscaldamento, mentre il confronto fra la concentrazione di ABA raggiunta nei campioni germinati, di controllo e trattati ha fatto supporre che, nel seme, si attivino diverse vie di segnalazione in grado di regolare da un lato l’omeostasi dell’ABA in risposta a diverse condizioni di stress e dall’altro la germinazione. L’analisi del proteoma ha rivelato la presenza di 46 proteine espresse in maniera differenziale fra i campioni trattati e il controllo, di cui 14 sono state sequenziale e identificate attraverso spettrometria di massa. Diverse, fra le proteine identificate, sono importanti fattori di risposta a situazioni di stress, essendo coinvolte nel metabolismo dei lipidi, nel folding proteico e nella protezione della cromatina. L’analisi del fosfoproteoma ha dimostrato che la funzione di molte proteine, soprattutto nei semi sottoposti a riscaldamento, è modulata attraverso modificazioni post-traduzionali. Questi risultati lasciano presupporre che i semi di M. marina adottano una strategia di dormienza basata sulla presenza di robusti tegumenti (hardseededness) in grado di prevenire l’assorbimento di acqua e la germinazione; inoltre la dormienza può essere regolata da altri complessi meccanismi fisiologici, quali la termoinibizione.
Da questi primi risultati, si è portato avanti lo studio volto a definire il ruolo di controllo della dormienza e della germinazione da parte dell’endosperma micropilare. A questo scopo, utilizzando la tecnica del puncture force, è stato misurato il weakening dell’endosperma micropilare nei semi sottoposti a scarificazione meccanica e a trattamento con ABA durante un time course di circa 22 ore. L’effetto dell’ABA è stato valutato anche sulla velocità e sul tasso di germinabilità finale dei semi sottoposti a tale trattamento. I risultati ottenuti hanno dimostrato che l’ABA è in grado di provocare un ritardo sia del weakening dell’endosperma sia della velocità di germinazione, che si traduce a sua volta in una considerevole diminuzione della percentuale di germinazione finale. In seguito, attraverso l’analisi del proteoma e l’analisi statistica multivariata sono state individuate 95 proteine che potrebbero rappresentare markers specifici dei diversi stati fisiologici, quando, superata la fase di dormienza il seme si prepara per la germinazione. Risultati preliminari suggeriscono che l’endosperma micropilare può contribuire all’instaurarsi della condizione di dormienza fisica che, ancora una volta, può essere rimossa efficacemente attraverso la scarificazione meccanica; inoltre l’ABA può svolgere un ruolo predominante nella regolazione temporale della geminazione, agendo sul weakening dell’endosperma micropilare.The general aim of this thesis is to understand the complex and unknown mechanisms underlying dormancy and germination of Medicago marina (L.), a Mediterranean species distributed along the whole coasts of Italian peninsula and adapted to living in a specialized life habitats, like the dunes. Seeds of this species show strong dormancy that prevents germination. Results obtained during the first period of PhD program are published in a paper by Scippa et al., (2011). An integrated approach of physiological analyses and proteomics was used to investigate the mechanisms that control M. marina dormancy/germination and that underlie stress tolerance. First, was evaluated the effects on dormancy breaking of the following treatments: mechanical scarification, freezing at -20 °C, storage for 4 months and heating at 100 °C for 1 h. Mechanical scarification and freezing were the most effective treatments in overcoming dormancy. The role of abscisic acid (ABA) in M. marina dormancy was studied by ELISA immuno-enzymatic assay, determining the ABA content of germinated and non germinated mature (control) and treated seeds. The level of ABA was higher in treated seeds than in control seeds; the most significant increase occurred in the heated seeds. A comparison of the ABA level in the germinated, control and treated seeds suggests that different mechanisms modulate ABA content in response to different stresses, and that a specific ABA-signaling pathway regulates germination. Proteomic analysis revealed 46 proteins differentially expressed between treated and untreated seeds; 14 of these proteins were subsequently identified by mass spectrometry. Several of the proteins identified are important factors in the stress response, and are involved in such diverse functions as lipid metabolism, protein folding and chromatin protection. Lastly, an analysis of the phosphoproteome maps showed that the function of many proteins in seeds subjected to temperature treatment is modulated through post-translational modifications. Taken together, the data obtained showed that M. marina seeds adopt a dormancy strategy based on a hard seed coats, known as hardseededness, which prevent water uptake and germination; also, dormancy it can be regulated by other complex mechanisms beside seed coats, such as thermoinhibition, a delaying mechanisms of germination adopted by different species during late summer or early autumn. Starting from these first results, the PhD project proceeded in further investigations of mechanisms involved in the control of germination timing and dormancy establishment, due to the mechanical constraints of the micropylar endosperm, besides the seed coat. In order to accomplish this aim, the weakening of the endosperm was analyzed trough the puncture force measurements in seeds subjected to mechanical scarification and ABA treatment, along a 22 hours time course of imbibition. In addition to that, the effect of ABA and gibberellic acid treatments on germination rate and speed, were analyzed by performing germination test. Results obtained from the puncture force and germination tests for scarified seeds treated or not with ABA, revealed that the endosperm weakening, occurring in M. marina seeds before the germination, is delayed by ABA, which deferred also the germination of treated seeds. Then, the using of 2D analysis coupled whit the multivariate statistical analysis allowed the individuation of 95 spots that represent specific markers of different physiological states and might be expressed in seeds when dormancy is overcome in order to complete germination. First results suggest that the micropylar endosperm can contribute to the establishment of M. marina physical dormancy, that once again, it can be removed by mechanical scarification. Moreover, abscisic acid seems to be strongly involved in regulation of germination timing, by its action on micropylar endosperm weakening.
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Metcalf, Daniel James. "Seed size, litter and regeneration in tropical rain forest trees." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336743.
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Kidd, Sarah Ann. "Ecosystem Recovery in Estuarine Wetlands of the Columbia River Estuary." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3637.
Full textAbstract:
In the restoration of tidal wetland ecosystems, potential drivers of plant community development range from biotic controls (e.g. plant competition, seed dispersal) to abiotic controls (e.g. tidal flooding, salinity levels). How these controls influence the success of tidal wetland restoration are only partly understood, but have important implications for wetland habitat recovery. Specifically, the extent to which the existing native and non-native seed banks in tidally reconnected wetlands interact with these controls is not clear, yet the potential success of passive restoration methods depends upon this understanding.
For a 54-year chronosequence of eleven tidal wetland restoration sites in the Lower Columbia River of western Oregon, USA, it was hypothesized that native plant species and soil properties would show trends approaching reference levels within 3 to 20 years post-restoration and that lower elevation wetland areas within restored sites would exhibit a greater native species abundance and similarity to reference sites, compared with restored high elevation wetland areas. Results indicated that plant species richness, soil organic matter, bulk density, pH, and salinity conditions among the restoration sites reached reference wetland ranges within 3-6 years post-tidal reconnection. The mid-low marsh elevation zones (<2.5 m) recovered native plant cover within 3-6 years post-tidal reconnection, while high marsh elevation zones (>2.5 m) remained dominated by nonnative species Phalaris arundinacea and Juncus effusus subsp. effusus.
To investigate the mechanisms driving these non-native plant invasions, it was ii hypothesized that native and non-native wetland plant community distributions would be reflective both of their abundance in the seed bank and of their germination tolerance to wetland tidal flooding and salinity conditions. Using a factorial study design of three tidal conditions by three salinity levels, these hypotheses were tested in the greenhouse. Overall, non-native seeds were found to significantly outnumber native seeds in both seed banks. In the greenhouse, P. arundinacea and J. effusus were found to germinate more readily out of the seed bank under freshwater high-marsh flooding (1 hour a day) treatments as compared to oligohaline (3 ppt) mid-low marsh flooding (3-6 hours twice a day) treatments and to brackish salinity (10 ppt) treatments. Dominant native wetland species, Carex lyngbyei and Schoenoplectus lacustris, germination were not found to vary significantly among the treatments (p > 0.10).
These results indicate that the salinity and flooding gradients within these restored marshes suppress germination of the non-native species in the low-mid marsh but not in the high marsh, where they are likely able to outcompete the native species due to their dominance in the seed bank. The implications of these results for passive tidal wetland restoration efforts are that both seed bank composition and species-specific tolerances to restored tidal flooding and salinity gradients are key mechanisms driving native and nonnative plant community development and resilience.
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Saeidi, Ghodratollah. "The effect of seed colour and linolenic acid concentration on germination, seed vigour, seed quality and agronomic characteristics of flax." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27429.pdf.
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Redfearn, Melanie. "Nucleic acid integrity and synthesis in relation to seed vigour in sugar beet." Thesis, Open University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321321.
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Legesse, Nigussu. "Genotypic comparisons of imbibition in chickpea (Cicer arietinum L.) and cowpea (Vigna unguiculata (L.) Walp.)." Thesis, University of Aberdeen, 1991. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU546773.
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Examination of the imbibition characteristics of eighty chickpea genetic lines (53 Desi and 27 Kabuli types) and eleven cowpea cultivars revealed that in both species seeds with unpigmented testae imbibed more rapidly than the pigmented seeds. Rapid imbibition was associated with high solute leakage, indicative of possible imbibition damage. Further evidence of imbibition damage was revealed in cowpea where the rapidly imbibing unpigmented seeds had poor vital staining with tetrazolium chloride after 24h imbibition. In chickpea, all the genetic lines of white Kabuli seeds had similar rapid rates of imbibition. In contrast, the pigmented Desi genetic lines revealed a range of rates of water uptake although many imbibed more slowly than the Kabuli lines. The incidence of delayed imbibers, that is, seeds which failed to imbibe until after 8h in water, was the main reason for reduced rates of imbibition in Desi lines. The restriction to water uptake by the pigmented seeds was mainly influenced by the properties of the seed coat. In cowpea seeds, the permeability of the seed coat was the most important factor limiting water uptake whereas in chickpea the permeability of the seed coat as a whole and of the micropyle as well as the degree of adherence of the seed coat to the cotyledons were important in regulating the movement of water into the seed. Investigation of the rate of imbibition during the maturation of dwarf French bean, cowpea and chickpea seeds revealed that development of slow water uptake by coloured cultivars was clearly associated with the appearance of pigmentation. In chickpea, this also coincided with the development of the adherence of the seed coat to the cotyledons. In contrast, seeds from unpigmented cultivars imbibed rapidly at all stages of maturation. Examination of the seed coat anatomy of chickpea and cowpea indicated that the pigmented seeds tended to have shorter and narrower palisade cells and also shorter tracheid bars than the unpigmented seeds. Differences in water uptake by Kabuli and Desi seeds were not evident when seeds were stored at 100% relative humidity and 40oC for days. All seeds deteriorated at a similar rate. However, the importance of initial seed quality in influencing deterioration during storage was emphasised by the rapid loss of germination of the Kabuli seeds in which germination and vital staining revealed poor initial quality.
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Daws, Matthew. "Mechanisms of plant species coexistence in a semi-deciduous tropical forest in Panama." Thesis, University of Aberdeen, 2002. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU160354.
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Niche-differentiation has been proposed to explain the coexistence of large numbers of tree species in tropical forests. Previous studies on established individuals have found little evidence for this. However, niche-differentiation may be apparent at the seed and seedling stages. This study investigated the effects of environmental variation in germination and seedling establishment for a range of Central Panamanian species. Firstly, topography has a large impact on soil water availability; slopes are wetter than nearby plateaux. The potential impact on seedling emergence and survival was studied by monitoring seedling emergence and survival over 15 months. This revealed that small-seeded species are unlikely to establish on plateaux, presumably because of the rider conditions. Secondly, the germination of four pioneer species in response to four environmental variables, related to canopy gap size, was investigated. Species exhibited consistent patterns of response suggesting adaptation for germination in particular gap sizes; Piper marginatum responded to nitrate, had a low base potential for germination and tolerated large temperature fluctuations, suggesting adaptation for germination in comparatively large gaps. Conversely, Pipe peltatum exhibited responses, which suggested adaptations for germination in small gaps. Finally, germination and seedling mortality for four pioneer species in two sizes of canopy gap was predicted using computer modelling. This indicated that large-seeded pioneers can germinate and establish in large gaps. Conversely, percentage germination and survival of small-seeded species was low in large gaps. However, small-seeded species produce greater quantities of seed than large-seeded species. Consequently they may "win by default" in large gaps, because of the absence of seeds of larger species. These results indicate that there are a number of axes of environmental variation along with nice-differentiation can occur. Furthermore, the response is variable between species. Thus niche-differentiation is important for fostering species coexistence, although density-dependent mortality and dispersal-limitation also contribute.