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Study on Physiological Mechanism of Genotype Difference of Water and Nitrogen Effective Use in Winter Wheat and Summer Maize in Guan Zhong

Author: ZhangYan
Tutor: DiBingNian
School: Northwest University of Science and Technology
Course: Agricultural environmental protection and food safety
Keywords: Winter wheat Summer maize Water and Nitrogen use effiency Genotype difference Physiological mechanism
CLC: S513
Type: Master's thesis
Year: 2009
Downloads: 45
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Abstract

Arid and semiarid areas are main areas of agricultural production in our country. Water shortage and nutrient deficiency are two key factors that restricted crop production in these areas.It is an important one in rational utilizing resources, decreasing environmental pollution and reducing inputs that exploiting plant descendible characteristics and potential of water and nutrients use, cultivating or utilizing genotype with high water and nutrition use efficiency, among these methods and approaches. Lots of studies on the screening of genotypes have been reported , but little have been done to understand the physiological mechanism in which summer maize and winter wheat genotypes can use water and nitrogen efficiently. The objective of this study is to identify the physiological mechanism and to offer the theoretic basis for promoting and cultivating genotype with high water and nutrition use efficiency. Two experiments were carried out to discuss the difference of the physiological mechanism of different genotypes by using growth analysis and physiological testing method from the viewpoint of the metabolism, defense enzymes & kinetics of nitrate and ammonium and &root characteristics etal. with two genotypes(After having been studying for past several years, the genotype(Xiaoyan 22 and HD4) with high effect high response and the genotype(Xiaoyan6 and YY22) with low effect low response were screened from 10 local dominating summer corn and winter wheat varieties.) under local environment. The main results are as follows:1. Applying nitrogen promoted the seedling growth, in different nitrogen level HD4 biomass significantly greater than YY22. In normal water, applying nitrogen improved Xiaoyan22 and Xiaoyan6 shoot, but nitrogen increased, root dry weight decreased, that showed root/shoot decreases gradually. In water stress, shoot obviously decreased, but root significantly increased, proper amount of nitrogen made shoot and root the maximum, especially Xiaoyan22.2. In low and middle nitrogen level, HD4 and YY22 NR activity apperently increased with increasing nitrogen supply, and the former was higher than the latter. But high nitrogen inhibited HD4 NR activity. Water stress lowered wheat chlorophyll content, but Xiaoyan22 was obviously higher than Xiaoyan6.3. Applying nitrogen accelerated HD4 and YY22 root activity, in low and middle nitrogen level, the former was remarkably the latter, HD4 root activity in high nitrogen reduced. In water and nitrogen stress Xiaoyan6 root activity was minimum.4. Whether normal or water stress with increasing nitrogen supply, winter shoot and root water content increased. And at the same nitrogen level, Xiaoyan22shoot and root water content was higher than Xiaoyan6. Water stress leaf water potential(LWP) was lower than normal. Whether normal or water stress with increasing nitrogen supply, Xiaoyan22 and Xiaoyan6 LWP obviously increased. At the same nitrogen level, the former was always higher than the latter.5. Water stress decreased winter shoot and root nitrogen content, nitrogen in root was higher than in shoot. Applying nitrogen improved shoot and root nitrogen content whether normal or water stress. At the same nitrogen level, nitrogen in Xiaoyan22 was always higher than in Xiaoyan6.6. Xiaoyan22 Superoxide Dismutase (SOD), peroxidase(POD), catalase (CAT) activity, malondialdehyde (MDA)and Pro content was high than Xiaoyan6 under water and nitrogen stress, Xiaoyan 22 showed strong stress-resistance.7. When NO3- and NH4+ solution concentration increased, absorption rate of experimental wheat varieties root increased at seedling stage. The order of maximum absorption rate(Vmax) and affinity (1/Km) among different varieties was Xiaoyan22> Xiaoyan6.

Study on Physiological Mechanism of Genotype Difference of Water and Nitrogen Effective Use in Winter Wheat and Summer Maize in Guan Zhong

Abstract

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