Nfluence Of Water Supply And Phosphorus Application In Different Depth On Growth And Yield Of Winter Wheat

Soil water and phosphorus are important material basis for crop growth，but also are themajor factor to limit crop yield, water use efficiency (WUE) and phosphorus utilization ratioin dry land. How to improve soil and the nutrient of crop absorbability though effectiveagricultural measures is the hot and focus problem for us. The experiment on effects of watersupply and phosphorus application in different depth on root distribution, yield, WUE andphosphorus utilization ratio of winter wheat was of theoretical and practical importance tophosphorus and growth in dryland farming. Main conclusions could be drawn from theproject:1. While the effect of phosphorus placement on the photosynthetic performance andyield on winter wheat was different for soil water and cultivar. Deep phosphorus applicationmay not increase SPAD, Pn, Tr and yield of winter wheat When water was well-supplied;Deep phosphorus application can improve indexes mentioned above when soil water supplywas deficient, especially on drought-tolerant cultivar. From cultivar, Changhan58had asignificant higher for yield than Xiaoyan22(P<0.05); from water treatment, theshort-supplied treatment could reduce the SPAD, Pn, Tr and yield of Xiaoyan22, comparedwith the well-supplied treatment, but increase yield of Changhan58. The phosphorustreatment (SP, DP and DBP) had no significant influence on SPAD, Pn, Tr and yield ofdrought-sensitive cultivar (Xiaoyan22) under the two water condition. For drought-tolerantcultivar (Changhan58), deep phosphorus application can decrease SPAD, Pn, Tr and yieldcompared with surface phosphorus application when water well-supplied; but it was oppositeunder the short-supplied condition, deep phosphorus application can increase SPAD, Pn, Trand yield compared with surface phosphorus application (P<0.05).2. Phosphorus placement and irrigation may have a significantl impact on root dryweight, root length and water use efficiency (WUE) of winter wheat, affecting rootdistribution. Root dry weightt, root length and WUE on winter wheat under the wholephysiology term decreased with soil depth in vertical direction, particularly ondrought-sensitive cultivar. Water stress made the surface soil root (0-20cm) fell remarkably,but it made the deep soil root (30-100cm) and WUE increased. Deep phosphorus application increase deep soil root (30-100cm) and WUE of winter wheat compared with surfacephosphorus application under the two water treatment. Further, root dry weight and rootlength in deep soil layer (30-100cm) were closely positively correlated with grain yield andWUE of Changhan58(but not Xiaoyan22), highlighting the connections between awell-developed subsoil root system and both high grain yield and WUE for thedrought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars.3. While the effect of phosphorus placement on root P efficiency ration, phosphorusutilizationand ration and PFPPof winter wheat was different for soil water and cultivar. Underwater well-supplied condition, deep phosphorus application was not only increase aboveindex; under water short-supplied condition, deep phosphorus application can improveindexes mentioned above on Changhan58, but it decrease on Xiaoyan22, especially ondrought-tolerant cultivar. Xiaoyan22had a significant higher for phosphorus efficiency thanChanghan58when water well-supplied (P<0.05), but it’s opposite when water short-supplied,Changhan58had a significant higher for phosphorus efficiency than Xiaoyan22. From watertreatment, the water short-supplied treatment could improve root P efficiency ration comparedwith the water well-supplied treatment. However, the water short-supplied treatmentdecreased phosphorus utilizationand ration and PFPPon drought-sensitive cultivar, but it’sopposite on drought-tolerant cultivar. Under the water well-supplied condition, deepphosphorus application can decrease phosphorus utilizationand ration and PFPPon twocultivar compared with surface phosphorus application; under the water short-suppliedcondition, deep phosphorus application can decrease phosphorus utilizationand ration andPFPPon drought-sensitive cultivar, compared with surface phosphorus application (P<0.05),but it’s opposite on drought-tolerant cultivar,.4. The results showed that phosphate fertilizer increased soil available P, organic P andalkaline phosphatase activity after harvest (P<0.05). While the effect of water and phosphorusplacement on the above index of winter wheat was different for soil depth and cultivar. Deepphosphorus application could not only increase available P, organic P and alkalinephosphatase activity in deep soil layer, but also increase above index in surface soil layer(0-30cm), especially under water stress. The short-supplied treatment could reduce availableP, organic P and alkaline phosphatase activity in surface soil layer, but it can improve theabove index in deep soil layer. The correlation analysis showed that, Whether or not irrigation,there were remarkable positive correlativity between alkaline phosphatase activity and rootlength, root dry weight, organic P on the two winter wheat.5. Taken together, our results reveal that deep application of phosphorus fertilizer is apractical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.