Effects of Irrigation Amount on Water Use Characteristics and Grain Yield of Wheat Under Different Phosphorus Application Rates

A field experiment was conducted to examine the effects of irrigation amount on the water consumption,flag leaf physiological characteristics,and grain yield of wheat under the phosphorus application rates 90 kg/hm2(P1) and 180 kg/hm2(P2).Four irrigation amounts were set with no irrigation during whole growth period(W0),irrigation with 60 mm water at jointing stage(W1),irrigation with 60 mm water at jointing and anthesis stage(W2),irrigation with 60 mm water at jointing and anthesis and filling stage(W3),respectively.The results indicated that under the same phosphorus rates,with increasing irrigation,water consumption amount increased,but the ratio of precipitation amount and soil water amount to water consumption amount reduced significantly.Compared with the P1 treatment,P2 treatment soil water consumption of 0-100 cm was significantly higher than that of P1 treatment,and also improved the proportion of soil water consumption for total water consumption,it indicated that addition phosphorus fertilizer could improve the use of soil water of winter wheat.At mid and late grain-filling stages,the relative water content(RWC) and water potential(ψw) of flag leaves were higher in treatments W2 and W3 than in treatments W0 and W1.The RWC and ψw at late grain-filling stage were higher in treatments P2W0 and P2W1 than in treatments P1W0 and P1W1,respectively.Based on these results,it is concluded that treatment with phosphorus application at P2O5 90 kg/hm2,irrigation at 120 mm could get high grain yield and water use efficiency(WUE),and phosphorus use efficiency,while over-irrigation increased the water consumption amount,and decreased the WUE,irrigation water use efficiency(WUEI),and the soil storage water consumption.