Wheat Grain Yield And Its Nutrient Uptake And Utilization Affected By Cultivation Patterns In Dryland

The Loess Plateau dryland is one of the main wheat production area in China.However,in this area,water deficit and low soil fertility inhibit the improvement of wheat grain yield and grain mineral nutrient uptake and utilization.Optimizing cultivation patterns is an effective approach for improving soil moisture and nutrient status,and then increase crop nutrient absorption and utilization and yield formation.Therefore,a 9-year-long location-fixed field experiment was conducted in the Loess Plateau to investigate the effects of plastic film mulching?PM?,straw retention?SR?and planting green manure?GM?on grain yield and nutrient concentrations of winter wheat.Exploring the relationship between cultivation patterns,wheat yield,grain nutrients,and soil nutrient changes by analyzing winter wheat biomass,harvest index,grain yield components,nutrient uptake and utilization,and the changes of soil nutrient.The major purposes of this study were to provide the theoretic base and technical support for optimizing soil fertility,increasing yield and improving the mineral nutritional quality of wheat in dryland.The main results were as followed:1.Plastic film mulching is not conducive to improve of soil fertility,thus inhibiting the grain yield formation and adversely affecting grain nutrients in dryland.Compared to traditional patterns?TP?,soil pH was increased and soil total N,available P,K,S,Zn and Mn concentrations were decreased in 20-40 cm soil layer,but no significant effect was observed on soil organic matter,NO₃^--N,available Fe and Cu concentrations with plastic film mulching.It increased spike numbers by 12.2%,but kernel numbers per spike and harvest index were decreased respectively by 14.7%and 8.5%.As a result,plastic film mulching had no significant effect on the average yield over the three years.The average P uptake and concentration in grain increased by 8.4%and 13.0%,respectively,The K concentration was increased by 5.0%,but no significant effect was observed for grain K uptake.The average uptakes of N,Ca,S,Fe and Cu were decreased respectively by 12.6%,10.3%,15.0%,11.1%,and 13.2%and the corresponding concentrations were decreased by 12.1%,8.0%,12.9%,10.1%and 9.0%.It had no significant effect on the average concentrations and uptakes of Mg,Zn and Mn.2.Straw retention showed no significant effect on the improvement of soil fertility and also no impact was observed for wheat grain yield and mineral nutrient concentrations in dryland with low soil fertility.Compared to traditional patterns,soil total N concentration was increased by 5.8%in 0-20 cm soil and available Cu concentration was increased by 6.2%in 20-40 cm soil,while available P and Mn concentration were decreased by 36.1%and 10.2%at maturity stage with straw retention.But there were no significant effects on the soil organic matter,NO₃^--N concentration,available K,S,Zn and Fe concentration at anthesis and maturity stage.Straw retention decreased aboveground biomass and kernel numbers per spike by 11.5%and 8.8%,respectively.As a result,grain yield was decreased by 12.1%.The average uptake of P in grain was decreased by 9.8%with straw retention,while the P concentration was increased by 5.0%.The average uptakes of N,Ca,S,Fe and Mn decreased by 22.5%,20.7%,21.0%,19.8%and 16.8%,and their corresponding concentrations decreased by 10.1%,8.0%,9.4%,3.8%and6.3%,respectively.The average uptake of K,Mg and Zn decreased by 11.5%,14.7%and 13.9%,but their corresponding concentrations showed no significant variance.At the same time,no significant effect was observed on the grain Cu concentration and uptake.3.Planting green manure could improve soil fertility and then increase grain nutrient concentration,but wheat yields have been unstable for a long time,mainly due to the large variations in annual precipitation and its distribution over seasons.Compared to traditional patterns,planting green manure decreased soil pH,available P and S concentration,but increased soil organic matter,total N,NO₃^--N,available Zn and Mn concentrations.It had no significant effect on soil available K,Fe and Cu concentrations.Aboveground biomass and spike numbers were decreased by 15.4%and 12.2%respectively.Consequently,grain yield was decreased by 12.1%.It had no significant effect on the average uptake of N,Zn and Cu,but increased the grain N,Zn and Cu concentrations by 12.1%,12.6%and 11.8%,respectively.The average uptake of P,K,Ca,Mg,S and Fe decreased by 11.9%,12.0%,10.3%,11.8%,13.0%and 15.9%,but their corresponding concentration showed no significant variance.The average P uptake and concentration in grain decreased by 17.7%and 7.1%,respectively.In conclusion,plastic film mulching,straw retention and planting green manure did not meet both high yield,high nutritional quality and high soil fertility.Plastic film mulching decreased soil fertility and grain nutrient concentrations,especially N,Ca,S,Fe and Cu concentrations,but increased P and K concentrations without significant effect on yield.Straw retention decreased grain yield,but increased grain P concentration and soil total N concentration in 0-20 cm soil.Planting green manure decreased the grain yield,but increased the grain N and Zn concentrations and improve soil fertility,especially soil organic matter and total N concentration.Hence,it is necessary to choose appropriate cultivation pattern on the basis of objective requirement in dryland of the Loess Plateau in China.