Effects of different nitrogen and phosphorus levels on seed yield and quality parameters of double high and double low Brassica napus

A pot culture experiment was conducted to study effects of different nitrogen(N)and phosphorus(P)levels on plant growth at the seedling stage of rape seed, seed yield and main quality parameters of Ningyou-7(double high Brassica napus cv.)and Tapidor(double low Brassica napus cv.). The results show that shoot dry weight at the seedling stage and seed yield of Ningyou-7 are higher than those of Tapidor under both P- and N-deficient conditions. P accumulations in shoot and seed of Ningyou-7 are higher than those of Tapidor without applying P. However, under both low and normal P conditions, P contents in shoot and seed of Ningyou-7 are lower than those of Tapidor. Under the low N treatment, more N is accumulated in shoot and seed of Ningyou-7 than that of Tapidor. These results indicate that there are significant differences between Ningyou-7 and Tapidor under the N and P efficiencies. The increment of seed oil content of Tapidor is higher than that of Ningyou-7 with the P application, and the increment of seed protein content of Tapidor is lower than that of Ningyou-7 with the N application. For Tapidor, seed glucosinolate content is significantly enhanced under the N application and erucic acid content is strongly decreased under the P application. However, applications of N and P have little effect on seed glucosinolate and erucic acid content of Ningyou-7. These results indicate that the effects of N and P on the seed quality of Tapidor are significantly greater than those of Ningyou-7.