Study On The Relationship Between Fertilizer Rate And Rapeseed (Brassica Napus. L) Yield And Quality And Its Nutrient Content

A field experiment was conducted to study the relationship between fertilizer rate and rapeseed(Brassica napus var.Zhongyouza No.11) nutrient content and its seed yield and quality,by using mixed-uniform design.The field soil contained 0.217%of total nitrogen,13.58mg/kg of available phosphorus and 105mg/kg of potassium,and 91.04mg/ kg of exchangeable magnesium and 18.13mg/kg of available sulfur.The results showed:The significance probability of the regression equation between fertilizer rate and seed yield was 0.0487,with the effect sequence on seed yield of the fertilizers was: S(X₅)＞N(X₁)＞K₂O(X₃)＞P₂O₅(X₂)＞MgO(X₄).The interaction of X₂X₅ affected the yield significantly.The seed yield was higher when either high P with low S or low P with high S,but the yield was lower when P and S application were in middle level.The optimum fertilizers rate(kg/hm²) aimed high yielding were N255.78-259.01,P₂O₅129.87-131.50, K₂O127.51-130.08,MgO7.40-7.74,and S1.96-2.06.Path-analysis of yield and its compo -nents showed the significance of components to yield was pods per unit area＞grains per pod＞1000-grain weight.The significance probability of the regression equation of fertilizer rate and protein and oil content was 0.0099,0.0091 respectively,influencing sequence on protein content was K₂O(X₃)＞P₂O₅(X₂)＞MgO(X₄)＞N(X₁)＞S(X₅).And with the influencing sequence on oil content was N(X₁)＞K₂O(X₃)＞P₂O₅(X₂)＞MgO(X₄)＞S(X₅).Protein content was greatly affected by the interaction of K and Mg.Oil content was greatly affected by the interaction of N and P,Higher protein content could be obtained when K and Mg fertilizers were at the low-low level or high-high level.Higher oil content could be obtained when N and P fertilizers were at the high-low level or low-high level.To achieve oil content beyond 41%and protein content beyond 20%,the optimum fertilizer rate (kg/hm²) was,N240.51-245.31,P₂O₅ 136.78-139.12,K₂O143.25-146.82,MgO5.67-6.06, and S 2.98-3.11.At seedling period,TN content was correlated to N fertilizer negatively and extremely significantly at 16DAT(Days After Transplanting),to Mg fertilizer negatively significantly and positively extremely significantly at 16DAT and 86DAT respectively.TP content was correlated to N fertilizer negatively significantly at 16DAT,to P fertilizer positively significantly also at 16DAT.TK content was correlated to K fertilizer positively extremely significantly at 86DAT.At flowering period,TN content was positively correlated to N fertilizer significantly at 137DAT,but negatively correlated to K fertilizer whereas extremely significantly positive at 161DAT.TP content was negatively related to K fertilizer significantly at 167DAT,positively related to Mg fertilizer significantly at 145DAT,and negatively related to S fertilizer extremely significantly and significantly at 137DAT and 167DAT respectively.TK content was negatively related to N fertilizer significantly at 161DAT,but positively related to Mg fertilizer significantly at 161DAT.The correlation of total N and total P was positive during seedling and flowering,the correlation of total K and total P was positive,but the correlation level didn't achieve significant during flowering,the correlation of total N and total K was positive in seedling, but it was negative correlation in flowering.It seemed that the higher content of N in the late period of seedling,the higher content of N in the late period of flowering.The content of total K in 58 DAT affected the total K positively during flowering.The total P correlation between seedling and flowering was not prominent.Rapeseed NPK content was related to its yield significantly,in which NPK content at flowering period had a closer relation to yield than that at seedling period.TN was correlated to yield significantly positive at 137DAT,but extremely significantly negative at both 154DAT and 161DAT.TP was correlated to yield extremely significantly positive at both 16DAT and 154DAT.TK was correlated to yield extremely significantly negative at 16DAT,but significantly positive at 137DAT.That higher P content,moderate content of N and lower content of K at early growing period and lower N,higher K content at late growing period would be beneficial to rapeseed yield.