Effects Of Nitrogen Application And Alternate Partial Root Zone Irrigation On Growth, Water Use Efficiency And Grain Yield Of Winter Wheat

Regulation of water and nitrogen is an important factor for crop growth and yield, therefore,the coupling between the water and nitrogen interaction study has important theoretical significance. Potexperiments were carried out on winter wheat （Triticum aestivum） and there are different water andnitrogen treatments. Effects of different nitrogen application rate and irrigation models on winter wheatgrowth, physiology, yield and water use efficiency were discussed. It is significant for promoting wheatresilience and increasing yield. Pot experiments were carried out on winter wheat cultivar dwarf resistant58under a movable rain shelter to study the effects of nitrogen fertilization and irrigation methods ongrowth, photosynthesis, water use efficiency, and grain yield. There were two fertilization treatments（2.73gN/pot and5.46gN/pot） and two water treatment regimes （soil water content was maintainedrespectively at75%-85%and45%-55%of the field capacity）. The high water content regime was furtherdivided by irrigation method into two sub-types （conventional irrigation and split-root alternateirrigation）. The results showed that conventional treatment （adequate water supply punctuated by adrought during the elongation period） affected winter wheat more strongly than split-root alternateirrigation when the normal dosage of nitrogen fertilizer was applied. Different irrigation methods hadsimilar effects when nitrogen fertilizer dosage was high.1. The height, leaf number and tilling number of winter wheat were higher under split-rootalternate irrigation than under conventional treatment, but the differences were not statistically significant.Aboveground biomass of the plants treated with high N dosage was not significantly affected by drought,while plants treated with normal N dosage lost a significant portion of aboveground biomass following the drought. Upon reaching maturity, plants treated with normal N dosage and split-root alternateirrigation had the lowest levels of aboveground organ biomass. Plants treated with split-root alternateirrigation had the highest levels of root biomass during the booting stage and upon reaching maturity, theR/S ratio was significantly lower under high nitrogen dosage.2. Net photosynthetic rate, stomatal conductance and transpiration rate of the normally treatedwinter wheat did not bounce back to levels seen in the control group post-drought, and intercellular CO₂concentration of the normally treated wheat was significantly higher than that of the control group.Different irrigation methods had similar effects when the dosage of nitrogen fertilizer was high.3. Soluble sugar content increased in stems, leaves and sheaths post-drought. That in leavesincreased significantly under all treatments, that in stems was little affected under split-root alternateirrigation, that in sheaths increased only under split-root alternate irrigation when the normal dosage ofnitrogen fertilizer was applied. Soluble sugar content of the root was lowest under conventional irrigation.Split-root alternate irrigation had little effect on roots’ soluble sugar content. Under high N dosage,soluble sugar levels of all organs decreased, while starch concentrations increased.4. WUE increased for all treatment groups post-drought. WUE of the conventional irrigationand split-root alternative irrigation treatment groups was respectively1.23and1.46times higher thanthat of the control group, while grain yield of these two treatment groups was respectively20.07%and10.57%lower than that of the control group. Under high N dosage, all groups had elevated WUE levelsand did not suffer yield loss.