Effects of Growth Type, Sowing Date, and Sowing Rate on the Canopy Architecture, Protein Yields, and Oil Yields of Winter Oilseed Rape (Brassica napus L.)

A split-split-plot design was used to evaluate the effects of sowing dates and sowing rates on three winter rape cultivars, including ‘PR45D03’, a semi-dwarf hybrid, ‘PR46W31’, a traditional hybrid, and ‘Californium’, an open-pollinated cultivar. August 25 was the optimal sowing date for maximizing protein and oil yields across all three cultivars. Of the cultivars, the traditional hybrid, ‘PR46W31’, produced the highest protein and oil yields on that date. The yields of the semi-dwarf hybrid, ‘PR45D03, were greater than those of the open-pollinated cultivar, ‘Californium’, when these were sown later than the optimal date. Protein and oil yields did not differ significantly among different seeding densities.