The Relationship Between Genotype Difference On Nitrogen Efficiency And Key Enzyme Activity During The Nitrogen Metabolism Of Wheat Cultivars

Under high and low N application levels, a pot experiment with eight wheat cultivars mainly in Henan were conducted to study the relationship between genotype difference on N efficiency and key enzyme activity during the nitrogen metabolism in wheat. Furthermore, the select index of high N efficiency traits were discussed as well, the aim is to provide scientific gist of the utilization, selecting and breeding and improvement of the N efficiency in wheat cultivars. The main results were as follows:1. Increasing nitrogen amounts could improve significantly the grain yields of all cultivars tested. They were related to N sensitivity of cultivars. Grain yields of Zheng004, Taikong6, Zheng9023, Zhoumail6 and Yumai50 were higher than that of other cultivars tested at two N levels. Yields of Taikong6 and Zheng9405 increased significantly. Under high N level, the amount of N uptake and protein content were improved evidently, the uptake efficiency, utilization efficiency, N efficiency and N harvest index were all decreased.2. N efficiency among all wheat cultivars had obvious differences. They could be separated into 2 nitrogen efficiency types, that is (1) High efficiency under two N levels, the cultivars were Zheng004, Zheng9023, Zhoumail6,Yumai50 and Taikong6; (2) Low efficiency under two N levels, the cultivars were Lankao906, Zheng9405 and Yumai47. By path analysis, it was found that both N uptake efficiency and N utilization efficiency had direct role in controlling N efficiency. However, under low N, N efficiency depended mainly on uptake efficiency, but at high N, it depended mainly on uptake efficiency and utilization efficiency.3. Chlorophyll content may be used as a very important indicator to reflect the photosynthesis ability of wheat leaves. Chlorophyll content had evident difference among all wheat cultivars after flowering. It decreased slowly at first and increased slowly in 7th day after flowering and decreased fast in 21st day after flowering, decreasing rate was related to senile rate of cultivars. Chlorophyll contents of flag leaf of Yumai 47 and Zheng9023 were higher; ones of Zheng9405 and Lankao906 were...