Assessing the contribution of genetic enhancements and fertilizer application regimes on canola yield and production risk in Manitoba

The number of canola varieties released, since the enactment of Plant Breeders' Rights (PBR) legislation in Canada in 1990, has increased substantively. The effect of genetic enhancements, including PBR, on canola yield and its variance is estimated for canola production regions of Manitoba using the Just-Pope production function. Diagnostic tests reveal the presence of heteroscedasticity in the data. The percentage of varieties seeded with PBR has a negligible effect on canola yield. Hybrid and herbicide tolerant varieties (HY/HT) seeded on over 90% of canola production area increases average yield by about 6.8%. Increased spatial diversity (more varieties planted on fewer acres) has reduced canola yield by up to 1.7%. Temporal diversity (turnover of varieties) has no significant impact on yield. Nitrogen and sulphur fertilizers are yield increasing. The variance of yield is not impacted by PBR, HY/HT, other technology measures, or by fertilizer other than potassium. Canola breeding programs have not compromised canola yield stability.