Responses of Seed Yield and Economic Benefit of Winter Oilseed Rape(Brassica napus L.) to Different NPK Ratio and Dose

Field experiments were conducted during 2008-2010 to investigate the effects of NPK fertilization on seed yield and economic benefit of a new hybrid cultivar of winter oilseed rape(Brassica napus L.)- Xiangzayou763,and to determine the optimum NPK ratio and dose in Hunan,China.The results showed that NPK ratio(1:0.50:0.50) with 180 kg/hm2 N,90 kg/hm2P2O5and 90 kg/hm2K2O was the optimum combination for the highest seed yield(2 231.13 kg/hm2) and economic benefit(9 816.97 Yuan/hm2),of which 1 641.23 Yuan/hm2being set for fertilizer investment(VCR=4.11).Besides,the effects of N,P and K fertilizers on seed yield and oil production of winter oilseed rape were not identical.N had the greatest effect on plant growth of winter oilseed rape,followed by P and K.Total leaf number,green leaf number,leaf length and width,rhizome diameter,branch number,dry weight per plant and other agronomic characters in high N treatments were higher than those in low N treatments.By correlation and path analysis of yield components,the contribution rate to seed yield was found:effective silique number per plant>seed number per silique>1 000-seed weight.