Parent Offspring Conflict Over Seed Dormancy in Sunflower (Helianthus Annuus L.) PDF Download
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Author: RADHA M. R
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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Author: RADHA M. R
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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Author:
Publisher: Allied Publishers
ISBN: 9788177640212
Category : Botany
Languages : en
Pages : 608
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Author: Carol C. Baskin
Publisher: Elsevier
ISBN: 0124166830
Category : Science
Languages : en
Pages : 1601
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The new edition of Seeds contains new information on many topics discussed in the first edition, such as fruit/seed heteromorphism, breaking of physical dormancy and effects of inbreeding depression on germination. New topics have been added to each chapter, including dichotomous keys to types of seeds and kinds of dormancy; a hierarchical dormancy classification system; role of seed banks in restoration of plant communities; and seed germination in relation to parental effects, pollen competition, local adaption, climate change and karrikinolide in smoke from burning plants. The database for the world biogeography of seed dormancy has been expanded from 3,580 to about 13,600 species. New insights are presented on seed dormancy and germination ecology of species with specialized life cycles or habitat requirements such as orchids, parasitic, aquatics and halophytes. Information from various fields of science has been combined with seed dormancy data to increase our understanding of the evolutionary/phylogenetic origins and relationships of the various kinds of seed dormancy (and nondormancy) and the conditions under which each may have evolved. This comprehensive synthesis of information on the ecology, biogeography and evolution of seeds provides a thorough overview of whole-seed biology that will facilitate and help focus research efforts. - Most wide-ranging and thorough account of whole-seed dormancy available - Contains information on dormancy and germination of more than 14,000 species from all the continents – even the two angiosperm species native to the Antarctica continent - Includes a taxonomic index so researchers can quickly find information on their study organism(s) and - Provides a dichotomous key for the kinds of seed dormancy - Topics range from fossil evidence of seed dormancy to molecular biology of seed dormancy - Much attention is given to the evolution of kinds of seed dormancy - Includes chapters on the basics of how to do seed dormancy studies; on special groups of plants, for example orchids, parasites, aquatics, halophytes; and one chapter devoted to soil seed banks - Contains a revised, up-dated classification scheme of seed dormancy, including a formula for each kind of dormancy - Detailed attention is given to physiological dormancy, the most common kind of dormancy on earth
Author: Robert L. Brunick
Publisher:
ISBN:
Category : Sunflowers
Languages : en
Pages : 218
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Elite inbred sunflower (Helianthus annuus L.) lines were found to have short-lived embryo and seed covering dormancies. Seed dormancy of wild sunflowers (H. annuus, H. argophyllus and H. exilis) was found to be controlled primarily by the seed covering (seed coat and pericarp) and embryo dormancy was short-lived (four to eight weeks). Native American Landraces (NALs) had low to moderate embryo and seed covering dormancy, which was more similar to elite lines. The seed covering in the NALs contributed more to seed dormancy than did the seed covering in the elite lines. The seed coat itself was implicated in seed dormancy and the length of dormancy caused by the seed coat varied by accession and variety. Excising 1/4 of the seed, rather than removing the entire seed covering, increased germination but also increased the number of seed that decayed. Dormancy of embryos from 19 wild sunflower accessions ranging in south to north latitude from Texas to Saskatchewan, Canada was found to be highly variable; however seed covering dormancy was similar among all the wild accessions in the northern latitudes. Germination of accessions in the most southern latitudes was greater (P
Author: Alexa Weiss
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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Abstract: Gene flow from agricultural crops into related wild plant populations can produce viable hybrid offspring with characteristics that differ significantly from those of their wild counterparts. Such crop-wild gene flow, especially in situations involving transgenic crops, has raised concerns about potential losses of genetic diversity, or increases in invasiveness, of wild relatives. The annual sunflower (Helianthus annuus) is an ideal species for studying crop-wild gene flow, the subsequent hybrid generations produced, and the effects on wild populations because the crop and wild types are often found in close proximity, are cross compatible, share pollinators, and are differentiated for important traits that may affect fitness, such as seed dormancy. Outside of cultivation, seeds that germinate in the fall are killed by the winter frost before reproducing, which has lead to the evolution of dormancy in wild populations; their seeds must experience a cold period before germinating in the spring. By contrast, cultivated varieties have been artificially selected to germinate immediately under favorable conditions. Consequently, the degree to which crop-wild hybrids germinate under fall conditions affects the extent to which crop genes may persist in, or introgress into, wild populations. Furthermore, the germination and dormancy characteristics of sunflower seeds, in particular, are due, in part, to the structural characteristics of their achenes (i.e., seeds and hulls). Most of these structures are maternally inherited while the genetics of the embryo involve contributions from both parents. This project determined the rates of germination and dormancy of fifteen crop-wild hybrid sunflower cross types and used microscopy to explore achene characteristics that could influence the differential germination we observed. Maternal effects (e.g., seed covering structures) had significant impacts on germination and dormancy, with crop-produced achenes germinating most readily, followed by those produced on F1 maternal plants, followed by those produced on wild plants. 3 The proportion of crop alleles (i.e., nuclear genetics of the embryo) was also important. There was a significant, positive relationship between the proportion of crop alleles and germination in the wild and F1 produced seeds. Microscopy revealed that maternal parent significantly affected achene size, embryo size, and relationships between structures and the micropylar (i.e., pointed) end of the achene. Crop produced achenes were largest and had minimal structural barriers to radicle (i.e, embryonic root) extension. F1 produced achenes were larger and had more substantial barriers which broke down quickly. Wild produced achenes were smallest and had the greatest barriers to radicle extension. Although they differed in size, structural characteristics, and germination rate, seeds produced on crop, F1, and wild maternal parents underwent the same general processes of leading up to germination. These findings suggest that crop alleles and the maternal effects associated with crop-wild hybridization can reduce dormancy, but that this reduction in dormancy may not be significant enough to prevent the introgression of crop alleles into wild populations.
![Seed Dormancy Studies in Sunflower [Helianthus Annuus L.] - Physical Basis Of, and Intraction Between Material and Embryo Tissues Over Seed Dormancy PDF](https://books.google.com/books/content/images/frontcover/jLmzXwAACAAJ?fife=w80-h100)
Author: K. S. Krishna Murty
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Author: Brent LaVerne Reschly
Publisher:
ISBN:
Category :
Languages : en
Pages : 92
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Sunflower (Helianthus annuus L.), is currently the second most important source of vegetable oil in the world. Seed dormancy in sunflowers poses a risk for off-season seed production in South America. Seed companies must hold the seed lots from sale until they meet minimum germination specifications and will not pose a risk for the customer. This investigation was undertaken to examine the differences in dormancy between SF270, a traditional oil sunflower hybrid, and X8927 a mid oleic sunflower hybrid. Seed was grown in Texas in 1999 and 2000. Samples were divided between three storage temperatures, constant 10°C, constant 14°C, and ambient room temperature and tested two times per month. The standard warm germination test, alternating 20-30°C warm germination test, and the ethrel warm germination test were used to evaluate germination and develop a dormancy profile for each genotype. A mathematical model was developed to calculate the average number of days to a specific germination value based on the laboratory germination data. The genotype SF270 broke dormancy soon after harvest, often before initial laboratory germination analysis could be completed. Genotype X8297 took longer to break dormancy than the traditional oil genotype. Both genotypes broke dormancy in a consistent pattern across the two production years. Storage of seed at constant 10°C, and constant 14°C prolonged the dormancy in both genotypes but, was more pronounced in the X8927 genotype. Storage at ambient room temperature had the most significant effect on breaking dormancy in the two genotypes. Of the three germination tests, the ethrel warm germination test was the best predictor of laboratory germination. Although these two genotypes cannot be considered representative of all genotypes, this study produced two very useful tools for seed producers. The model to calculate the average number of days after harvest to reach the target 85% germination goal, and the depth of dormancy or longevity of dormancy for a particular genotype. These tools can be used as a risk assessment tool to plan seed production placement, shipping, and anticipate product release.
Author: Brian Alexander Pace
Publisher:
ISBN:
Category :
Languages : en
Pages : 59
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Abstract: Although gene flow between crop and wild relatives is not a new area of study, much can still be learned through the investigation of hybrids between divergent taxon. Most crops exchange alleles with wild and weedy relatives, especially when grown in crop centers of origin. Such gene flow can result in evolutionary consequences for wild populations ranging from genetic erosion and demographic swamping to the evolution of enhanced weediness. All of these scenarios are concerning, since wild populations constitute a breeding pool in which valuable allelic diversity is stewarded and weeds already cause problems in agriculture. Helianthus annuus was domesticated in North America where its cultivated and wild forms have been known to hybridize when grown in proximity. However, cultivated sunflower and its relative, common sunflower, differ in morphology, ecological habit, and life history. For example, dormancy differs between crop and wild sunflower types since it was selected against during domestication, but has remained necessary for maintaining fitness for wild plants. Sunflower has physiological dormancy, but the strength and duration of dormancy differs between wild and crop types. Achenes resulting from hybridization between crop and wild sunflower have been shown to have reduced dormancy compared to wild achenes. Although the introgression of crop alleles into wild populations cannot occur unless the F1 generation survives to reproduce, the dormancy of later generations is important for determining if this trait could provide significant resistance to introgression. The objectives of this work were twofold: to identify how maternal parent and differing crop allele percentages each affect seed germination, dormancy, and mortality. Here, fifteen hybrid crosstypes were created on three different maternal plant types - wild F1 crop-wild hybrid, and crop. Since the pericarp and seed coat of sunflower achenes are maternal tissue, contrasting the three maternal types allowed for investigation of the impact of maternal effects in crop-wild sunflower hybrids on achene germination, dormancy, and survival. The genetic composition of these crosstypes varied from 0% to 100% crop alleles, with six intervening levels. All fifteen crosstypes were surveyed in a seed burial study, while two crosstypes were included a companion pericarp manipulation experiment. In the field experiment, three removal dates were chosen to assess hybrid seed germination, dormancy, and mortality. The contribution of crop alleles, maternal parent, and their interaction affected achene germination, dormancy, and survival. While crosstypes with higher crop allele percentages had increased early spring mortality compared to wild achenes, all crosstypes had high overwinter survival, indicating that reduced dormancy is not a complete barrier to crop allele introgression. However, hybrid achenes produced on wild maternal parents had high levels of dormancy that was comparable to wild dormancy, while crop-produced and F1-produced achenes had little to no dormancy by the last removal date, indicating that only hybrids produced on wild maternal plants will persist in the seed bank. Hybrid achenes remaining in the seed bank can be recruited in future years to backcross with wild plants or cross with remaining hybrids and may increase the risk of genetic erosion and demographic swamping.
Author:
Publisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 788
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Author:
Publisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 908
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