Made available in DSpace on 2014-08-20T13:44:34Z (GMT). No. of bitstreams: 1 dissertacao_ricardo_miotto_ternus.pdf: 674305 bytes, checksum: 64aa2364d9c050f8dcd0998e6895e80d (MD5) Previous issue date: 2013-08-29 / Due to its economic importance, soybean (Glycine max) has been the subject of intense research aimed at providing information leading to higher yield gains. With in this context, the use of legal seeds is considered an extremely important tool for farmers. However, for several reasons, farm-saved seeds or informal seeds are regularly used by farmers. Aiming to evaluate the soybean seed usage rate in the state of Santa Catarina, identify reasons explaining the use of legal or illegal seeds, and providing guide lines for sanitary education and supervision by the Integrated Agricultural Development Company of Santa Catarina (CIDASC), a survey research was under taken polling 103 soybean producers from different regions of the state. Data were collected from 12/01/2012 to 03/29/2013 in 67 municipalities of Santa Catarina located in soybean- producing regions. The results obtained showed that the rate of legal soybean seed usage in Santa Catarina for the last three growing seasons was 71.9, 73.4 and 79.6%, respectively. Seed lots with low vigor and sanitary problems are the main criteria that guide the producer's decision to opt for commercial seeds. The high price of commercial seeds and acceptable crop yields obtained from farmsaved seeds explain the use of saved or informal seed in the state of Santa Catarina. / A cultura da soja (Glycine max), em razão da importância econômica que possui, é alvo de intensa atividade de pesquisa dirigida na busca de informações que proporcionem ganhos de produtividade. Neste contexto, o uso de sementes legais constitui-se em uma ferramenta de extrema importância para o agricultor. Porém, por razões diversas, muitas vezes, os agricultores utilizam semente salva ou informal. Com o objetivo de avaliar a taxa de utilização de sementes de soja no estado de Santa Catarina, identificar os motivos que levam à utilização de semente legal ou ilegal, e visando nortear as ações de fiscalização e educação sanitária da Companhia Integrada de Desenvolvimento Agrícola de Santa Catarina (CIDASC), foi realizada uma pesquisa de levantamento com aplicação de 103 questionários, em usuários de sementes, nas diversas regiões produtoras do estado. Os dados foram coletados no período de 01/12/2012 até 29/03/2013 em 67 municípios catarinenses localizados nas regiões produtoras de soja. Os resultados obtidos mostram que: a taxa de utilização de sementes legais de soja em Santa Catarina nas três ultimas safras foram de 71,9, 73,4 e 79,6% respectivamente; a substituição de lotes com baixo vigor e com problemas sanitários são os principais critérios que fundamentam a decisão do usuário em optar pelo uso de sementes legais; e que o preço elevado das sementes legais aliado a uma produtividade aceitável são os critérios que determinam o uso das semente salva e informal no estado de Santa Catarina.

LD2668 .T4 1947 F56 / Master of Science

Call number: LD2668 .T4 1956 B76 / Master of Science

Call number: LD2668 .T4 1978 M92 / Master of Science

Thesis (PhD (Agric.) -- Stellenbosch University, 1984. / INTRODUCTION: The study of seed dormancy and germination has for centuries occupied the minds of agronomists, physiologists, brewers, bakers and, more recently, weed scientists. The agronomist requires that the seed that he sows will germinate rapidly and uniformly and produce a vigorous healthy seedling .. The physiologist is interested in the understanding of the basic processes involved at the molecular level, and the geneticist in the inheritance of the quiescent character of the seed. Brewers seek a seed that will retain its viability at least until the following crop is harvested but which will also, on imbibition, rapidly set in motion those processes that will convert starch into sugar. The baker is concerned with the baking quality of the seed and, as far as he is concerned~ the more dormant the seed the better, as this eliminates the problem of pre-harvest sprouting which is very detrimental to baking quality. The weed scientist seeks to encourage all weed seeds present in the soil to germinate simultaneously so as to enable him to destroy the weed population with one application of herbicide or a single cultivation.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy

Germination of seeds of desert annual plants is reduced where there are high densities of annual seedlings. This is interpreted as a response by seeds to avoid a severe biotic environment in which growth rate and fecundity are likely to be reduced by larger established competitors. This density-dependent germination response is due primarily to reduced germination of small-seeded annuals where densities of large-seeded annuals are high. Because of this germination response, and because of competition at the plant stage, large-seeded annuals could, in the absence of significant levels of predation by seed-eating rodents, dominate the annual plant community to a much greater extent than is commonly observed. By reducing densities of large-seeded annuals, rodents allow densities of small-seeded annuals to increase and thus exert a positive indirect effect on granivorous ants. Seed-eating rodents and a parasitic fungus both prey on Erodium cicutarium, a dominant annual plant. These two unrelated predators significantly influence each other's densities by their use of a common prey species. Dispersal of desert annual seeds that successfully germinate is apparently not as widespread as is suggested by observations that some desert annual seeds are redistributed throughout the year by wind and water. Removal of plants during seed set significantly reduced densities of seedlings on sample plots the next year.

Guayule (Parthenium argentatum Gray) is one of two major plants in the world grown for natural rubber and therefore, is of potential importance to the U.S. One area of research interest relates to methods of enhancing production of viable seeds. Therefore, studies were conducted in 1984, 1985, and 1986, in Tucson, Arizona to determine the effect of honey bee pollination on: seed set; seed weight; total seed yield; percentage of seed germination; yield and percentage of rubber and resin content. This experiment involved four guayule cultivars and four pollination treatments: plants caged with bees; plants caged without bees; plants open-pollinated; and plants individually covered with Delnet bags. All four cultivars responded positively to honey bee pollination. Plots with bees produced at least 195% more seeds than plots from which bees were excluded. However, there were no qualitative differences in the seed weights between the treatments. The percentage of seed germination from plots serviced by bees was significantly greater (65%) than from plots without bees (50%). Highest seed germination rates were obtained when seeds were collected in May (80%) and September (76%). June, July, and August seed collections resulted in lower seed germination rates (40%, 26%, and 63%, respectively). The plots in which bees were present gave a higher rubber yield (323 kg/ha) than plots without bees (255 kg/ha). However, there were no quantitative differences in the percentage of resin content between the treatments. These studies demonstrated that (1) honey bees can increase seed yield, seed germination, and rubber content in guayule, and (2) seeds produced during summer months had poorer germination rates and lower yields.