The ecology of Brassica napus
Seerey, Nicole J.
Volunteer canola (Brassica napus L.) has become an abundant weed in western Canadian cropping systems. Modern canola cultivars are strong competitors and produce large seed yields, however seed shattering during harvest creates large volunteer seedbanks. The segregation of hybrid trait and changes in variability of traits may allow successive generations of volunteer B. napus weeds to display different levels of fitness and other traits. Three cultivars: 2 hybrid, and 1 open-pollinated at three consecutive generations: G1, the initial crop; G2, first generation of volunteers; and G3 the second generation of volunteers, were used to evaluate the competitive ability, fitness and population dynamics of volunteer canola when grown as a weed in wheat (Triticum aestivum L.). Traits including seed, biomass, and pod production, plant height, seed weight, dormancy, and competitive ability were measured. In all traits but height and seed weight, hybrid breakdown occurred, as the hybrid G1displayed greater mean values than the G2 generation. Hybrids commonly showed the highest mean values of various traits in the G1, lowest mean values in the G2. Hybrid G3 populations produced mean values not different from the G1 or G2 generations for many traits. The open-pollinated cultivar displayed mean values for all traits which did not vary across generations. Generational differences in B. napus seedlings resulted in differences in wheat yield losses. B. napus densities at maturity provided a more robust model of wheat yield loss, as there were differences in wheat yield losses due to the interaction of generation and cultivar of B. napus. Commercial seed generations were the most competitive and fit plants, while volunteer generations were less competitive, and not as fit.
DegreeMaster of Agriculture (M.Agr.)
SupervisorDr, Kirstin Bett; Shirtliffe, Steve
CommitteeCoulman, Bruce; Bai, Yuguang; Légère, Anne
Copyright DateApril 2010