Seed loss in canola (Brassica napus, Brassica rapa and Brassica juncea) leads to considerable loss of revenue and dispersal of canola seeds into the soil seedbank. Once canola seeds enter the soil seedbank a portion can become secondarily dormant and persist for many years creating volunteer weed problems in following crops. Reducing canola seed loss and seedbank persistence can be an important strategy to reduce the incidence of volunteer weeds. The primary hypothesis of this research was that canola seedbank addition and dormancy induction in the seed are affected by genotype and harvest method. To test this hypothesis, three studies were conducted with the following objectives: i) to determine canola seedbank addition from windrowing and direct-harvesting operations on commercial farms in western Canada, ii) to determine agronomic- and harvest-related factors that may increase seed loss in canola, iii) to determine the effect of stage of crop maturity at harvest on potential to develop seed dormancy in canola, iv) to evaluate canola genotypes and harvest methods to reduce canola seedbank addition. A total of 66 canola fields were surveyed across Saskatchewan in 2010 and 2011. Shattered seeds from these fields were sampled within 3 weeks of harvest by using a vacuum cleaner. Agronomic- and harvest-related data were collected for each field using questionnaires. In a separate small plot study the effects of harvest methods (windrowing and direct-harvesting) and pod sealant products (Pod-Stik® and Pod Ceal DC®) on seed loss in five canola genotypes (InVigor5440, RR45H26, InVigor5020, RR4362, and CL8571) were evaluated in 2010 and 2011. In both years, 6 harvest samples were collected weekly from InVigor5440 and InVigor5020 genotypes starting at early stage of crop maturity until harvest to assess the effect of seed maturity on dormancy induction. On commercial farms, the average seedbank addition was 5,821 viable seeds m-2, which was equivalent to 7.3% of the total seed yield. There was no difference in the reported yield and seedbank addition between windrowed and direct-harvested canola on commercial farms. But in the small plot study, windrowing resulted in higher seedbank addition. Higher seedbank addition was observed when the yield of canola was higher and when producers had a larger area seeded to canola. The observed seedbank addition was also higher in Roundup Ready genotypes and when a conventional combine harvester was used to harvest canola. Little primary dormancy and low potential to secondary dormancy induction was observed in InVigor5440 and InVigor5020 seeds at an early stage of crop maturity. But at full maturity seeds of both genotypes had no primary dormancy but showed high potential for secondary dormancy induction. This indicates that windrowing the evaluated genotypes at early stage of crop maturity lowered the potential for secondary dormancy induction. There were appreciable differences in seedbank addition among the evaluated canola genotypes but pod sealant products did not affect seed yield and seed shatter in canola. The results of this study suggest that canola seedbank addition can be minimized by growing genotypes having reduced seed loss and with the adoption of direct-harvesting operations.

Made available in DSpace on 2014-08-20T13:44:42Z (GMT). No. of bitstreams: 1 dissertacao_ronaldo_meireles.pdf: 289382 bytes, checksum: 2d2b3fb010bc8a7cf9186236cd6bf5d4 (MD5) Previous issue date: 2008-05-05 / The seed producer enterprises need to be feasible to keep themselves in the market. The evaluations about the proceeding methods of production are necessary. By this way the work had the objective of studying the evolution of soybean seed production at the Cooperativa Agruindustrial Consolata Ltda. In order to make this study historic data of the production and the processing and commercial of the seed was taken, from the year 2002/03 to 2006/07. The parameters, evaluated for each year, were: received seed volume, loss during their processing (based on the discharged material), low quality seed lot and commercialized seed lot. The data have been appreciated in percentage for five classes of germination and varietal purity and three physical purity classes. The results led to the following conclusions: the seed producer fields performances could be higher, demanding an intensification at the internal quality program. Still, there s a certain necessity of adopting more adequate techniques to make the seed production and the efficiency at the processes even better. Seed commercialization was about 100% in terms of seed lots approved. / As empresas que produzem sementes precisam ser eficientes para permanecerem no mercado. As avaliações dos processos de produção são necessárias para a manutenção da viabilidade econômica da empresa. Dentro desta premissa o trabalho tem o objetivo de estudar a produção de sementes de soja na Cooperativa Agroindustrial Consolata Ltda. Para isso, foram utilizados os dados históricos relativos à produção e processamento de lotes de sementes comerciais nas safras 2002/03 a 2006/07. Os parâmetros avaliados para cada ano foram: volume de sementes recebidas e as perdas ocorridas durante o processamento das mesmas, determinada com base no descarte de materiais indesejáveis na classificação de lotes de sementes de baixa qualidade e da não comercialização de sementes. Os dados foram apreciados em percentual para cinco classes de germinação e pureza varietal e de três classes de pureza física. A análise dos dados, bem como a interpretação dos resultados permitiu concluir que: o aproveitamento dos campos para produção de sementes pode ser melhorado, exigindo uma intensificação no programa interno de qualidade, que existe também a necessidade de adotar técnicas mais adequadas para melhorar a produção das sementes e a eficiência nos processos e que a comercialização de sementes chegou a 100% dos lotes de sementes aprovados.

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