Effects Of Soil Water Content On Wheat Yield And Nitrogen Use Efficiency

During the growing season of wheat in 2019-2020,The experiment was conducted in the Shijiawangzi village,Xiaomeng Town,Yanzhou,Shandong Province.Yannong 1212 was selected as the test wheat variety in the experiment.The method of measuring soil moisture and supplementary irrigation was used for irrigation.Four water treatments were set up,namely,supplementary irrigation to 60%(W1),75%(W2),90%(W3)of soil relative water content in 0～40 cm soil layer at jointing stage and anthesis,and No-irrigation at the control treatment growth stage(W0).The results were as follows:1 Effects of soil water content on water consumption characteristics of wheatThe results showed that W3 was significantly higher than W1 and W2 in supplementary irrigation amount and total irrigation amount at jointing stage and anthesis;W2 was significantly lower than W3 in total water consumption,water consumption from jointing to anthesis and water consumption modulus coefficient at anthesis to maturity stage;W2 and W3 were significantly higher than W0 and W1 treatment;soil water storage consumption was similar to 40～140 The water consumption of W0 was significantly higher than that of W1,W2 and W3 in cm soil layer.The water consumption of W2 was the highest from anthesis to maturity.2 Effects of soil water content on soil nitrogen supply capacity of wheatThe contents of total nitrogen,inorganic nitrogen,organic nitrogen and microbial biomass nitrogen in 0～20 cm soil layer were significantly higher than those in 20～40 cm soil layer.The contents of soil total nitrogen,organic nitrogen reached the highest in the maturity,and the contents of soil inorganic nitrogen and microbial biomass nitrogen reached the highest at anthesis;the contents of soil total nitrogen,inorganic nitrogen and organic nitrogen in 0～20 cm and 20～40 cm soil layers from anthesis to maturity were significantly lower in W2 and W3 than in W0 and W1;the contents of soil inorganic nitrogen and microbial biomass nitrogen in 0～20 cm and 20～40 cm soil layers from anthesis to maturity were significantly lower in W2 and W3 than in W0 and W1 Among the treatments,W2 and W3 had the highest content of soil microbial biomass nitrogen.The results showed that W2 treatment had higher soil nitrogen supply capacity under water-saving condition.3 Effects of soil water content on nitrogen accumulation and distribution in wheat plantsW2 was the highest in nitrogen accumulation of plant at anthesis and maturity,nitrogen transfer and contribution rate of vegetative organs to grain before anthesis.Nitrogen accumulation of vegetative organs at anthesis and grain nitrogen accumulation at maturity stage in W2 was significantly higher than that in W0,W1 and W3.There was no significant difference in the activity of nitrate reductase,glutamine synthetase,endopeptidase,soluble protein and free amino acid in flag leaf at anthesis.The results showed that W2 and W3 treatment were significantly higher than those of W1 and W0 treatment at 7～14 days,14～21days and 21～28 days were significantly higher than that of other treatments.The results showed that W2 treatment was beneficial to nitrogen absorption and accumulation after anthesis,and maintained a high level of nitrogen metabolism.4 Effects of soil water content on dry matter accumulation and transport of wheatThe dry matter accumulation of W2 was significantly higher than that of other treatments at anthesis and maturity;the dry matter accumulation of W2 was the highest at maturity,followed by W1 and W3,and W0 was the lowest;The distribution and contribution rate of dry matter assimilates to grains after anthesis were significantly higher in W2 treatment than in W1 and W3 treatment;the grain filling rate of W2 was the highest at 7～14 d and 28～35 d,and it was at 0～7 d,14～21 d and 21～28 d There was no significant difference between W2 and W3.The results showed that W2 increased the accumulation of dry matter from anthesis to maturity,promoted the transport of dry matter to grain after anthesis,maintained a higher grain filling rate at the middle and late filling stage,and increased grain weight.5 Effects of different soil water content on wheat yield and nitrogen use efficiencyAmong the yield components of wheat,W2 treatment had the highest grain number per spike and 1000 grain weight,W2 and W3 had the highest grain yield,followed by W1,and W0 had the lowest;water use efficiency and nitrogen use efficiency of W2 and W3 were significantly higher than other treatments.Therefore,W2 is the best irrigation treatment for water saving,high yield and high nitrogen use.