Effects Of Nitrogen Application Rate On Grain Quality And Water And Fertilizer Utilization Of Wheat Under Water-Saving Irrigation Mode

In this study,on the basis of the physiological research on the water-saving and high yield of wheat,with the focus on improving the efficiency of water and fertilizer utilization and aiming at high quality,different nitrogen fertilizer dosage experiments were conducted under two irrigation patterns to study the growth and development,material production,quality formation and nitrogen absorption,operation and distribution rules of spring wheat,to elucidate the relationship between different N application rates and grain quality and water and fertilizer use,to reveal the compensation mechanism of N application rates on wheat grain quality,yield and water and fertilizer use efficiency,to clarify the appropriate N application rates for high quality and efficiency of water-saving irrigated wheat,and to provide a theoretical basis for establishing a water-saving,high quality and efficient cultivation technology system for wheat,with the following main findings:1 Under both irrigation modes,with increasing N application,wheat plant height,stem thickness and upper trifoliate area showed a trend of first increasing and then decreasing,and the plant morphological indexes of all treatments showed that conventional irrigation was greater than water-saving irrigation;with moderate N fertilization under both irrigation modes,wheat leaf senescence was slower,plant transpiration was reduced,leaf SPAD value,Fv/Fm value and net photosynthetic rate were higher,and canopy structure was suitable,which promoted The canopy structure was suitable,which promoted grain filling and dry matter accumulation.2 The water use efficiency(WUE)of the population showed a trend of increasing and then decreasing with the increase of N application,among which the highest WUE performance was in the N3 treatment,and the moderate chasing of N fertilizer promoted the increase of WUE of wheat.When comparing the two irrigation modes,the N content of the plants showed that water-saving irrigation > conventional irrigation,and the N uptake showed that conventional irrigation > water-saving irrigation.Nitrogen application was highly significantly(P < 0.01)positively correlated with plant N content,significantly(P <0.05),or highly significantly(P<0.01)negatively correlated with nitrogen productivity and nitrogen fertilizer bias productivity,and did not reach a significant level(P > 0.05)with other nitrogen use indicators.3 There were significant differences in wheat yield and its components between the two irrigation patterns.The measured yields and yield components of the conventional irrigation treatments were higher than those of the water-saving irrigation,and the number of spikes,number of grains,thousand grain weight and yield all tended to increase to different degrees with increasing N application;the number of spikes,number of grains and yield were affected by the irrigation pattern to a highly significant level(P<0.01).Thousand grain weight was not significantly affected by irrigation patterns(P > 0.05),while wheat yield and components were affected by nitrogen application and water-nitrogen interactions to a highly significant level(P <0.01).4 The effect of irrigation mode on grain protein content,wet gluten content,dough formation time,stretching area,settling value,dough extensibility,water absorption rate and maximum resistance to extension was highly significant(P < 0.01),showing that the water-saving irrigation mode > the conventional irrigation mode,while the difference between the two irrigation treatments was not significant(P > 0.05)in terms of capacity and flour yield.With increasing nitrogen application,seed protein content,wet gluten content,flour yield,water absorption,stretching area and dough extensibility all tended to increase,while dough formation time,settling value and maximum resistance to delay were not significantly different between the nitrogen treatments(P > 0.05).A comprehensive analysis showed that the appropriate N application rate(pure N)for achieving high quality,high yield and high efficiency of wheat under water-saving irrigation in Hetao irrigation area was 143.9-235.9 kg/hm2.