Studies On Yield Structure And Physiological Characteristic Of Rapeseed (Brasscia Napus L.) In Different Nitrogen Levels

Studied the relationship between the endogenous hormone, physiological characteristic and the yield of rapeseed in different nitrogen levels. The results showed that: the yield of treated varieties increased with the increasing of nitrogen application, and the pod number of plant was significantly increased, while the seed oil contents decreased. The chlorophyll content of the functional leaves also increased, the most significantly in elongation stage. Since the winter stage, the ratio of soluble sugar and total nitrogen of leaves of all varieties in low nitrogen nutrition was higher than the others. The ratio was the highest in the elongation stage and began to descend in the flowering stage. These results suggested that the lack of nitrogen could reduce the unbalance of the metabolism of the C and N.The results of the endogenous hormone analysis indicated that: the C/N of the functional leaves was very significantly relative to the GA/iPAs (r=0.997**) at the seedling stage. The high GA/iPAs of the functional leaves of low nitrogen level perhaps could speed the accumulating of the soluble sugar, which may be a sign of the unbalance of the metabolism of the C and N. During the elongation, the IAA content of the functional leaves of the high nitrogen level was more than the middle and low ones. In different varieties, from the winter stage to the primary flowering stage, the GA content of the functional leaves promoted with the increasing of nitrogen supplying. Then after the blooming stage, the GA content of the functional leaves in high nitrogen level was the lowest. During the flowering stage, promoting the nitrogen nutrition reduced the ABA content and GA/iPAs of the buds and increased the iPAs content and IAA/ABA. The accumulation of buds IAA atthe early flowering and buds ABA at the late flowering would have an influence on the last formation of flower. The low IAA and high iPAs percent content of the pods and the increasing of ABA content within 16 days after anthesis can promote the absorb of nutrient in the pods; Within 28 days after anthesis, the high IAA and low iPAs percent of the seed of Huashuang No.3. and tne low IAA content and high GA percent of seed capsule were very relative to the increasing of yield and the decreasing of seed oil content. Promoting the nitrogen nutrition increased the GA content of the pod capsule and decreased the GA content of the pod. Again, Huashuang No.3 and Huaza No.4 have the same change of the GA and ABA content and the IAA and GA percent of the functional leaves, but were different in the endogenous hormone content of pods. Finally, we can regulate the growth of rapeseed according those laws by applying nitrogen fertilizer and a suitable plant growth regulator at appropriate growth stages.