The Physiological Mechanism In Water And Nitrogen Effective Use Of Different Winter Wheat Genotypes

Water shortage and nutrient deficiency are key factors that restricted crop production in Arid and semiarid areas, limited water and nutrient can't fully use. Therefore improve the utilization efficiency of water and nutrient have become researching and pursuiting of the goal. Among these ways and approaches, it is an important one in remission the shortage of water and nitrogen resources, and increasing plant yield that exploiting plant descendible characteristics and potential of water and nutrients use, by cultivating or utilizing genotype with high water and nutrition use efficiency. Lots of studies on the screening of genotypes with higher NUE (nitrogen use efficiency) and WUE (water use efficiency) have been reported, but little have been done to understand the physiological mechanism in which winter wheat genotypes can use water and nitrogen efficiently. The experiment were carried out to discuss the difference of the physiological mechanism of different genotypes from metabolism, accumulation of dry matter, carbon and nitrogen transfer et al with two genotypes after having been studying for past several years. The genotype Xiaoyan 22 with high effect high response and the genotype Xiaoyan 6 with low effect low response were screened from local dominating winter wheat varieties. The main results are as follows:1. Canopy dry weight, RWC, root activity,leaf chlorophyll content were significantly increased under nitrogen application; root dry weight increased under nitrogen stress; water stress causing RWC and root activity increased under nitrogen stress;RWC of Xiaoyan 22 was higher than Xiaoyan 6. Xiaoyan 22 with high water and nitrogen use efficiency was more adaptable to water and nitrogen stress than Xiaoyan 6 with low water and nitrogen use efficiency, and physiological metabolism was more vigorous than Xiaoyan 6.2. Ear number, grain number and 1000-grain weight were increased significantly under nitrogen application, yield-increasing effect on Xiaoyan 22 were more apparent under nitrogen application. The results of yield components showed that the yield of Xiaoyan6 mainly dependent on effective spikes, otherwise 1000-grain weight and the number of spikes contribute to that of Xiaoyan 22.3. The net photosynthetic rate of Xiaoyan 22 are higher than that of Xiaoyan6 under nitrogen application. With nitrogen application increasing, leaf water use efficiency of Xiaoyan 6 decreased and Xiaoyan 22 decreased after increased at N150 treatment. The two genotypes winter wheat group water use efficiency increased under nitrogen treatment, and Xiaoyan 22 are higher than Xiaoyan6.4. The yield, nitrate reductase enzyme activity, leaf water potential and chlorophyll content were reduced significantly under no nitrogen application. But under the condition of nitrogen application, they were significantly increased. Leaf water potential and chlorophyll content of winter wheat leaf could be kept at the high level at 150 kg/hm2 nitrogen application. As far as two kinds of genotypes, the physiological activity of Xiaoyan 22 was more exuberant than Xiaoyan 6, nitrogen application strengthened this function.5. In the process of grain filling, stem, glume and grain soluble sugar content have the trend of slow- fast- slow; leaf soluble sugar content in nitrogen treatment have the trend of reduce-elevate, and in none-nitrogen treatment have the tread of reduce- elevate-reduce. Total nitrogen content of stem, leaf, grain have the trend of reduce- elevate, and glume total nitrogen content have the trend of reduce- elevate-reduce. Total nitrogen content of different winter wheat organ maintain in high level under 150 kg/hm2 nitrogen application. As two kind of different varieties, stem, leaf, glume soluble sugar content of Xiaoyan 22 are higher than Xiaoyan 6; Xiaoyan 22 grain soluble sugar content are higher than Xiaoyan 6 at earlier filling stage, Xiaoyan 22 grain soluble sugar content are lower than Xiaoyan 6 at late filling stage; total nitrogen content of Xiaoyan 22 are higher than Xiaoyan 6 in filling stage.