The Potential Yield And Resource Use Efficiency For Winter Wheat In Different Regions In China

Under the background of increasing population and food demand,the slow and even stagnated crop yield improvement,how to further increase grain production,improve resource use efficiency,and achieve sustainable development of agriculture was a major national demand for food security,and also a hot scientific issue.Wheat was one of the three major food crops in the world and it was a major crop in China.Under such a severe situation,it is critical to analyze the limiting factors and the limitation of winter wheat yield in different winter wheat regions in China and to clarify the resource use efficiency in each region.In this thesis,we focused on the major winter wheat planting regions in China.First,the agricultural production system simulation model(APSIM)was calibrated and evaluated respectively based on the Agrometeorological Experiment station data.Then the 3 grades potential yields of winter wheat during 1981-2015 were simulated by the validated APSIM model,considering the changes in variety in each region,including radiation-temperature potential yield,rainfed/irrigated potential yield and climate-soil-N potential yield.The distribution patterns and variations of each yield level,yield stability and yield suitability for the potential yields and actual yields were analyzed.After making clear the effects of water,soil-N and agronomic management and technology on yield level and stability for winter wheat,the resource use efficiency of winter wheat under different productive level in each region were assessed.The main conclusions were showed as below:(1)The APSIM-Wheat model was sensitive to radiation use efficiency(RUE).Based on the previous research method,the RUE at typical sites in each region was verified.The radiation-temperature potential yield increased significantly after RUE verification.The yield increase in Wuhan(the Middle and Lower Yangtze Valleys,YV)and Zhengzhou(the Yellow and Huai Valleys,YH)was higher at a ratio of 20.1%and 14.9%,respectively,with a high fraction of diffuse radiation(FDR)during winter wheat growing season,while the yield increase in Kunming(Southwestern China,SW)and Beijing(the Northern China Plain,NC)was relatively lower with a low fraction of diffuse radiation(FDR)during winter wheat growing season at a ratio of 7.9%and 7.6%,respectively.(2)For the radiation-temperature potential yield,the very suitable zones were mainly located in Shandong,southeastern part of Hebei,northwestern part of Henan in YH,northern part of Yunnan and southern Sichuan in SW;For the rainfed/irrigated potential yield,the very suitable zones were located in the southern area of Liaoning in NC,Shandong,southeastern part of Hebei,north of Jiangsu,Anhui and Henan,southern part of Shanxi,central part of Shaanxi in YH;For the climate-soil-N potential yield,the very suitable zones were mainly located in the southern part of Liaoning in NC,south of Shandong,most parts of Henan and southeastern area of Shaanxi in YH.For the actual yield,the very suitable zones were located in the eastern part of NC and YH,including the western area of Shandong,northern part of Henan and Jiangsu,in the central of Sichuan in SW and the central of Jiangsu in YV.(3)It was 19.8%,11.1%and 30.9%of the radiation-temperature potential yields for winter wheat that were affected by precipitation/irrigation,soil-N and agronomic management and technology,respectively.The coefficients of variation of yield increased by 5.2%and 0.7%under the effect of soil-N and agronomic management and technology,while the coefficients of variation of yield reduced by 1.5%under the effect of precipitation/irrigation.Agronomic management and technology was the major factor on the yield level and stability for winter wheat in the whole study region,NC and YH.In YV,precipitation was the major factor on the yield level and agronomic management and technology was the major factor on yield stability for winter wheat;In SW,agronomic management and technology was the major factor on the yield level and precipitation was the major factor on yield stability for winter wheat.(4)The radiation use efficiency and heat use efficiency during the winter wheat growing seasons were higher in the north than in the south among the study region.The water use efficiency(WUE)under the climate-soil-N productive level was the highest in YV,indicating that the optimum irrigation and fertilization management in YV can improve water use efficiency,while the WUE in other regions did not improve significantly.The WUE in NC was the lowest and that in SW was the highest among the study region.The partical factor productivity from applied N(PEP)and agronomic efficiency of applied N(AE)were highest under the climate-soil-N productive level.The PEP and AE were higher in NC,YH and YV than that in SW.