Manipulating Agronomic Factors for Optimum Canola Harvest Timing, Productivity and Crop Sequencing

Abstract

Harvest management for canola (Brassica napus L.) has changed such that the practice of straight-cutting now dominates. We sought to understand how manipulations to seeding rate, pod shatter reduction hybrid, and harvest method alters canola seed yield and quality. An experiment was conducted at five sites across the Canadian Prairies between 2018 and 2022, consisting of two hybrid cultivars that confer the pod shatter reduction trait with contrasting growth phenology seeded at rates of 60, 120, and 180 seeds m-2, and subjected to either swathing at 60% and 90% seed color change (SCC), or straight-cutting (S/C) at 10% and 5% seed moisture. Seeding rates of 120 and 180 seeds m-2 (~ 60 and 80 plants m-2, respectively) provided high and stable canola yield relative to 60 seeds m-2. At harvest, S/C at 10 % seed moisture was effective for both cultivars, but delays to the timing of S/C diminished any advantage over swathing at 90% SCC. Seed losses at harvest were rarely notable for both hybrids; the late-maturing cultivar expressed higher seed yield, seed bulk density and oil content. A partial least squares analysis indicated plant density (plants m-2), seed weight on the primary branches, and pod number on the secondary branches are critical yield components, and could facilitate superior yields for low seeding rate when environmental stress was low. This explains the temptation to reduce rates for economic considerations; however, utilizing 120 seeds m-2, coupled with timely S/C, ensures high seed yield and yield stability while minimizing seed losses.

Keywords: Canola, Brassica napus, GenotypexEnvironmentxManagement (GxExM), Harvest management, Sowing Density, Yield Stability