Effects Of Nitrogen Topdressing Stage And Soil Moisture On Grain Yield And Quality In Wheat And Their Physiological Basis

The physiological metabolism of carbon and nitrogen mechanism and the formation of grain yield and quality of different wheat cultivars was systematically studied using two winter wheat cultivars, Jimai 20 which has strong gluten potential and Taishan 23, which has medium gluten potential under different nitrogen topdressing stage and soil moisture condition through 15N isotope tracing technique, enzymological method and physiological and biochemical analysis method. The principal results were as follows.1 Effect of soil moisture on grain yield and quality of different wheat cultivar and its physiological basisThree irrigation treatments including unirrigation (expressed as W0), irrgation three times (expressed as W1), irrgation four times (expressed as W2) was setted up in order to study the characteristics of carbon and nitrogen metabolism of different wheat cultivars under different soil moisture condition. The principal results were as follows.1.1 Difference of flag leaf of different wheat cultivars in nitrogen metabolismIrrigation treatments increased the nitrate reductase(NR), endopeptidase(EP) and carboxypeptidase(CP) activity of flag leaf of Jimai 20 and Taishan 23 at middle and later stage of grain filling than unirrigation treatment. Irrigation four times increased the nitrogen assimilation ability of flag leaf of Jimai 20, but decreased the nitrogen degradation ability than irrigation three times, while the nitrogen assimilation and degradation ability of Taishan 23 had no significant difference between irrigation three times and irrigation four times.1.2 Difference of different wheat cultivars in protein components content of grain and the ratio of glutenin content to gliadin contentIrrigation treatments reduced gliadin content and increased glutenin content and the ratio of glutenin content to gliadin content of Jimai 20, but increased gliadin content and reduced...