Effects Of P, K And Mg Fertilizers Application On Growth And NPK Distribution Under Different Rotation Systems In Rapeseed

The trials were carried out in the production base of double-low rapeseed with high-quality in Nantong city, Jiangsu privince. The two main rotation systems (growing rapeseed after rice and growing rapeseed after cotton) were selected. The purpose of the research was to study the reasonable fertilization managements of rapeseed under different rotation systems through comparing the amount of dry matter of different organs, seed yield, the content and the amount of N, P and K in different growing stages, and NPK distribution of different organs at the maturing stage of Yangyou No.4 under the different P, K and Mg fertilizers application. The main results were as follows:1. Rotation systems had obvious effects on the growth of rapeseed. The amount of dry matter and the seed yield in different growing stages of rapeseed which growing after cotton were higher than that growing after rice, while the economic coefficient was opposite. Increasing P, K and Mg fertilizers application could increase the amount of dry matter of rapeseed under two rotation systems. Among the three fertilizers, the effect of phosphorus fertilizer was the largest and the magnesium fertilizer was the least. Increasing P, K fertilizers application also could increase the seed yield under two rotation systems, while the seed yield increased firstly and then decreased with the increasing of Mg fertilizer application under two rotation systems, especially growing rapeseed after rice. So applying too much Mg fertilizer didn't benefit the formation of seed yield. The effects of P, K and Mg fertilizers application on seed yield of rapeseed growing after rice was more than that after cotton. As a result, increasing the amount of dry matter of rapeseed growing after rice and increasing the economic coefficient of rapeseed growing after cotton were the basic fertilization strategy in improving the rapeseed yield in two rotation systems.2. The changing trend of N, P and K content under two rotation systems increased firstly and then decreased, except for K cotent of rapeseed growing after rice with'M'type. The total amount of N, P and K under different growing stages all increased with the growth of rapeseed. The effects P, K and Mg fertilizers on the content and total amount of N and P under different growing stages were similar. Among the three fertilizers, the effect of phosphorus fertilizer was the largest and the magnesium fertilizer was the least. But for the total amount of K, the effect of potassium fertilizer was larger and the magnesium fertilizer was the least. The total amount of N, P and K under different growing stages of rapeseed growing after cotton was higher than that after rice.3. The distribution of N and P in different organs in the maturing stage distributed mainly in seeds, then in stem and branches, least in pod shells. But the distribution of K mainly distributed in stem and branches, then in pod shells, least in seeds. The proportion of N and K in seeds of rapeseed growing after rice was higher than that after cotton, while the proportion in stem and branches was lower. The proportion of P in both rotation systems had no significantly difference. Fertilizer application could change the proportion of N, P and K in different organs in the maturing stage. In general, the proportion of N and P in seeds decreased with the increasing of fertilizers application.