Interaction Of Water And Phosphorus On Growth, Roots Carbon Consumption And Yield Of Spring Wheat

Interactions of water and phosphorus on growth,roots carbon consumption and yield of spring wheat were conducted by a potted plant experiment under an auto-rain-shelter.The cultivar of plant was selected:longchun 8275.Two soil water treatments were employed:drought stress(W₁,45%～50%of field water capacity) and well-water supply(W₂,75%～80%of field water capacity):three phosphorus treatments were also employed:no phosphorus(P0,0.00g),suitable phosphorus (P₁,0.10g)and high phosphorus(P₂,0.25g).In jointing and flowering stages,Some physiological parameters such as daily mean photosynthesis rate,root respiration rate, rhizosphere microbial respiration rate,shoot biomass,root biomass,leaf area,height, grain yield and yield components and so on were measured.The main objectives of this study were to analyze the effects of water and phosphorus on carbon consumption of roots and grain yield,in order to investigate the coupling of root's carbon consumption level and grain yield,furthermore,to provide some scientific basis for improving the grain yield of spring wheat.Main results were listed as follows:1.In jointing and flowering stages,among different water and phosphorus treatments, root respiration rate and rhizosphere microbial respiration rate would increase when the capacity of phosphorus and soil moisture dsed,But the specific root respiration rate and specific root rhizosphere microbial respiration rate would increase when the capacity of phosphorus rised,otherwise,they would decrease when the capacity of soil moisture rised.In all treatments,the results of high phosphorus P₂(0.25g)were highest in root respiration rate and rhizosphere microbial respiration rate.2.In jointing and flowering stages,among different water and phosphorus treatments, root biomass carbon and root respiration carbon consumption would increase when the capacity of phosphorus and soil moisture rised,moreover,and interactions of water and phosphorus were obvious,root exudation carbon consumption would increase when the capacity of phosphorus rised,otherwise,they would decrease when the capacity of soil moisture rised.In all treatments,the results of high phosphorus P₂(0.25g)were highest in root biomass carbon,root respiration carbon consumption and root exudation carbon consumption.3.In jointing and flowering stages,among different water and phosphorus treatments, diurnal photosynthesis carbon assimilation and percentage of it to total carbon consumption would increase when the capacity of phosphorus and soil moisture rised. In all treatments,the results of high phosphorus P₂(0.25g)were highest in diurnal photosynthesis carbon assimilation,percentage of it to total carbon consumption have the same results as diurnal photosynthesis carbon assimilation in well-water supply, otherwise,the results of suitable phosphorus P₁(0.10g)were highest in drought stress.4.In jointing and flowering stages,among different water and phosphorus treatments, leaf area would significantly increase when the capacity of phosphorus and soil moisture rised,root-shoot ratio were negative,in other word,the root-shoot ratios of no phosphorus P₀(0.00g)were higher than that of having phosphorus(P₁ and P₂),the root-shoot ratios of drought stress were higher than that of well-water supply.5.Of all the treatments,the shoot biomass of W₂P₁ was highest,W₁P₀ was lowest. Compared to the shoot biomass of drought stress,that of well-water supply increased by 57.24%,the results of suitable phosphorus P₁(0.10g)were highest in shoot biomass.6.Among different water and phosphorus treatments,the results of suitable phosphorus P₁(0.10g)were highest in grain yield and root efficiency.In drought stress, grain yield of W₁P₂ was lower than that of W₁P₀.In well-water supply,grain yield would significantly increase when the capacity of phosphorus rised,and was more than 2.1 times higher than that of drought stress.7.Different water and phosphorus combination have similar effects on water use efficiency of biomass and water use efficiency of grain yield,they would significantly increase when the capacity of soil moisture rised,and interactions of water and phosphorus were obvious.In all treatments,the results of suitable phosphorus P₁(0.10g)were highest in water use efficiency.