Effects Of Population Size And Its Regulation On Winter Wheat Water Use Efficiency And Yield Under Straw Mulching

Water deficit is the major limited factor for winter wheat production in the northwest arid area,population controlling could significantly influence wheat growth and water use pattern.The objective of this research was to investigate effects of population size,root pruning and defoliation on soil water storage,development of winter wheat,soluble sugars,grain yield and water use efficiency under straw mulching on dryland in Weibei Plateau.The field experiments involved seeding rates and population regulation measures,including 10 treatments which were high density with conventional tillage,normal density with conventional tillage,low density with conventional tillage,high density with mulching,normal density with mulching,low density with mulching,high density with root pruning under mulching,high density with defoliation under mulching,normal density with root pruning under mulching,normal density with defoliation under mulching.The main results obtained were as follows:(1)Straw mulching in fallow period stored 98 mm more water in 0-3m soil profile than conventional tilliage.Sowing densities mainly effected population size in seeding stage and wintering stage.Sowing densities and straw mulching didn't significantly effect wheat yield,but straw mulching significantly reduce the water use efficiency.The range of wheat yield is6414kg-6936kg/ha.The soluble sugar content on different wheat organs were not significant difference under different sowing densities,but at anthesis leaf soluble sugar content is significantly higher under straw mulching than that of conventional treatment,stem was opposite compared with leaf.In the harvest stem and shell of the soluble sugar content were higher than under conventional than mulching treatment.Under conventional treatment and straw mulching,wheat dry matter accumulation had no significant difference under different density treatment after anthesis,but the straw mulching treatment has a tendency to delay the filling stage.(2)Root pruning and defoliation had no significant influence on soil water in 0-3m.Root pruning had a tendency of reducing yield,but the water consumption was significantly reduced,thus the water use efficiency was improved.Root pruning and defoliation had significantly reduced the wheat biomass at harvest.The range of wheat yield is 5769-6496kg/ha.What's more,root pruning and defoliation had significantly increased the soluble sugar content of wheat stem and leaf separately.Based on the above results,in the year of experiment,sowing densities and straw mulching had not significantly affected winter wheat yield and its components.But straw mulching significantly reduced the HI and water use efficiency.Root pruning had no significantly effect on wheat yield but had high water use efficiency.Defoliation had significantly reduced wheat yield.Population controlling had affected soluble sugar content of wheat stem and leaf at anthesis.Therefore,the interactions between sowing densities and straw mulch need further research in other climatic conditions to comprehensively evaluate the impact of these factors.