Differential Responses of Seed Yield and Yield Components to Nutrient Deficiency Between Direct Sown and Transplanted Winter Oilseed Rape

Both transplanting and direct-sowing are the dominated methods for establishing winter oilseed rape in China. It is important to understand crop performances and responses to nutrient deficiency between transplanted oilseed rape (TOR) and direct sown oilseed rape (DOR). We estimated the effects of establishment methods (transplanting and direct-sowing) and nutrient deficiency (N, P, and K) on rapeseed yield, yield components, and nutrient uptake from 32 site-years field experiments. We found that DOR plants produced lower seed yield, dry matter, and harvest index than TOR plants. The population density in DOR was higher with poor individual growth as reflected by significantly reduced branches, pods, and seeds pod(-1). Thus, DOR plants were more sensitive to nutrient deficiency and would lose more yield under nutrient omission conditions. TOR and DOR yields significantly correlated with all yield components except for 1000-seed weight. Pod number plant(-1) showed the strongest direct effect on TOR yield. However, population density and pod number plant(-1) exhibited highest direct effect on DOR yield. The uptakes and harvest indexes of N and P were higher for TOR, while the DOR plots received higher K uptake and harvest index of K. DOR was more sensitive to nutrient deficiency and its nutrient management should be paid more attention.