The Research On The Nitrogen's Effect On Rapeseed Yield And Quality And Relevant Analysis

In this study, Brasscia napus L. cv. Zhongyou 821 and Brasscia napus cv. Huanshuang No.3 were researched in order to investigate the diversification of rape yields, quality, physiological mechanism, endogenetic hormones and the relationship among them under different nitrogenous level. The results of present study can be used to serve farmers, who could be able to regulate rape physiological and metabolic process through reasonably nitrogen fertilizing so that they can promote yields and improve quality.The main results were as followings:Increasing nitrogen fertilizer can prominently promote rape yields under the nitrogen supply at level of 22.5 Kg/667m~2, especially in lean soil. As for yield components, nitrogen applying increased producing more branches, growth of their branches, total number of effective branches and pods per branch, ability of photosynthesis, the number of effective pods of stem and seed dry weight per 1,000 seeds. So the yield can be promoted significantly. But as to different rape cultivars, influence of different nitrogen level on seed number per pod is not inerratic. For economic character, more nitrogen applying increased plants height, stem thickness, weight of stem and pericarp. What is more, nitrogen promoted producing branches.Influence of different nitrogen level on rapeseed quality was significant. More nitrogen applying evidently decreased oil content, and the influence was even more observable under higher level of nitrogen. On the contrary, nitrogen applying increased protein content, glucosinolate and erucic acid content. It was showed that influence of different nitrogen level on glucosinolate and erucic acid content was much more significant to Zhongyou 821 than Huanshuang No.3, the former is a "double-high"rape cultivar, but the latter is a "double-low" one. After 37 days post anthesis nitrogen began to influence the oil and protein formation. Nitrogen promoted protein formation and ultimately increased oil content.On the aspect of physiological metabolism, after 37 days post anthesis seed dry matter accumulated acceleratively and the dry weight increased, but for pericarp dry weight undergone a transformation from increasing to decreasing through the pods development. Seed cholorophyll content increased gradually until 30 days post anthesis and after that it began to decline. Meanwhile pod cholorophyll content decreased after 16 days post anthesis. More nitrogen applying increased accumulation of cholorophyll, so that the date of seed cholorophyll content increasing to the most was postponed 7 days, and at the same time pod cholorophyll content decreased. When late development of rapeseed, nitrogen applying diminished seed Cholorophyll a/b value, and increased pod cholorophyll a/b value in reverse. Therefore functional period of pericarp was prolonged.As for soluble sugar content, soluble sugar content of Zhongyou 821 increased according to more nitrogen applying, contrary to that of Huanshuang No.3. Before 45 days post anthesis rapeseed soluble sugar content gradually decreased and after that it changed scarcely. More nitrogen applying activated glutamine synthetase (GS) of seed and pericarp during the late development and delayed losing its activeness. Lastly nitrogen applying increased IAA and IPAs content of pericarp so that functional period was prolonged and its output was inhanced greatly. But for influence of nitrogen on auxin of seed, IAA and IPAs content of less nitrogen applying was more than that of more nitrogen applying.Under different nitrogenous level, the formation of the production and the quality of rape has certain inter-relationship with physiological mechanism. Two-year experiment has shown that branches and the pods per branch has significant negative correlation with oil content, and has significant positive correlation with protein content During the growing process, the oil content has negative correlation with the change of the content of cholorophyll, glucosinolate has positive correlation with GS activity in seed. And it also shows that the content of protein has antagonistic function glucosinolate content.