Effect Of Shading On Nitrogen Metabolism And Grain Quality Under Different Nitrogen Rate In Wheat

Based on wheat with different sensitivity to shading,three nitrogen levels(0,120,240 kg N·hm-2)and two shading treatments(No shading and shading 60 % of nature light)were set up.The effects of nitrogen and shading on yield,grain protein content and starch content on wheat quality were systematically studied.The results showed that:The photosynthesis ability of wheat was improved by the increasing nitrogen application,but was reduced by the shading.Both nitrogen application and shading could improve the utilization of light energy in wheat.Nitrogen application could increase dry matter accumulation and promote the transport of dry matter in wheat,which had the opposite effect to shading.Shading reduced the 1000 grains weight by decreasing the average grain filling rate and maximum grain filling rate.The increased nitrogen application mainly increased the number spikes of wheat and then increased the yield significantly,while shading reduced the number of grains of per spike of wheat and significantly reduced 1000 grains weight,resulting in a significant decrease in yield.The increased nitrogen application was beneficial to the nitrogen accumulation and transport in wheat.Under the same nitrogen application condition,shading increased the nitrogen transport of Jimai22.Both shading and nitrogen application could significantly increase the activity of nitrate reductase in flag leaves,and the increased nitrogen application significantly increased the activity of nitrate reductase in grains of wheat.The increased nitrogen application increased the activity of glutamine synthetase both in flag leaves and grains of wheat,but shading had the opposite effect to nitrogen application.Nitrogen application increased the content of free amino acids significantly both in flag leaves and grains of wheat.Under the same nitrogen application condition,shading increased the content of free amino acids in flag leaves and decreased the content of free amino acids in grains.Nitrogen application increased the content of soluble protein in the flag leaves of wheat,which had the opposite effect to shading.Both nitrogen application and shading could significantly increased protein content in grains of wheat.The increased nitrogen application could increase the content of starch,amylopectin and amylose content,and shading had the opposite effect.Both the increased nitrogen application and shading could improve the gelatinization enthalpy of wheat starch,and with the increase of nitrogen application,the gelatinization enthalpy was increased.Increasing nitrogen fertilizer increased the aging rate of Jimai 22 and reduced the aging rate of Jihe916.Under the same nitrogen application condition,shading had the opposite effect to nitrogen fertilizer.The correlation analysis showed that the amylopectin and starch content were negatively correlated with the termination temperature and positively correlated with the gelatinization enthalpy.Amylose content was significantly positively correlated with starch peak viscosity and dilute value.Amylose content was significantly positively correlated with starch through viscosity.Both nitrogen application and shading could improve the development time and stability time of dough,which were beneficial to the processing quality of wheat flour.the nitrogen application increased the gelatinization enthalpy of wheat flour,however,under the same nitrogen application condition,the effect of shading on thermodynamic properties and flour viscosity were different because of the different cultivars.Nitrogen fertilizer increased the peak viscosity,through viscosity,final viscosity and rebound value of wheat.