Effect Of Variety,Density,Water And Fertilizer Amount On Yield,the Absorption And Utilization Of Water And Nutrient Of Wheat-maize

At present,the basic situation of Chinese agriculture is low water utilization,decreasing cultivated land,the waste of resources and the environment pollution caused by excessive fertilization.In order to cope with these problems and protect the development of Chinese agriculture,it is ensential to achieve high yields and save water and fertilizer.Wheat-Maize rotation is the main planting pattern in China.Water and fertilizer,density and variety are important factors affecting crops yield.Moreover,there are close interactions between these three factors.Therefore,two summer maize experiments and a winter wheat experiment were conducted under the condition of straw recycling.One maize experiment includes ten maize varieties and three densities.The other maize experiment includes four maize varieties,three densities and three water and fertilizer amounts.The wheat experiment includes nine wheat varieties and three water and fertilizer amounts.Based on analyzing yields,water and nutrient use efficiency of different varieties and densities at different water and fertilizer amounts,these experiments aim to improve yields,water and nutrient use efficiency by optimizing variety,density,water and fertilizer amout.The main results are as follows:?1?Yield and water use efficiency of different water and fertilizer amounts have significant difference.Increasing water and fertilizer amount can increase yields.Water use efficiency of different varieties have significant difference.Appropriately increasing the density can increase yields and water use efficiency.However,if the density is too high,it will leat to the decrease of yields and water use efficiency.The suitable density that yield and water use efficiency reached the maximum is different.The suitable density of Tunyu808,Xianyu335,Xianyu1266,Shanndan609,Xinong211 and Huanong138 is 82500 plants/hm²,and that of Zhengdan958,Shanndan226 and Yanke288 is 75000 plants/hm².?2?Increasing water and fertilizer amount can increase total absorption of nitrogen,phosphorus and potassium,but it will decrease the use efficiency of nitrogen,phosphorus and potassium.Appropriately increasing the density can increase absorption of nitrogen,phosphorus and potassium.However,if the density is too high,it will decrease the absorption of nitrogen,phosphorus and potassium.The responses of nitrogen,phosphorus and potassium use efficiency of each varieties to density were different.At three water and fertilizer amounts,with increasing density,nitrogen,phosphorus and potassium use efficiency of Xianyu1266 and Huanong138increase firstly and then decrease.With increasing density,nitrogen use efficiency of Tunyu808increases firstly and then decreases,but phosphorus and potassium use efficiency will decrease.Increasing density leads to the decrease of nitrogen,phosphorus and potassium use efficiency of Zhengdan958.?3?Water and fertilizer amount and variety have significant effects on yield and biomass of wheat.Variey also have significant effect on harvest index.Increasing water and fertilizers amount will increase yields and biomass.All varieties will achieve the maximum yield and biomass at high level of water and fertilizer?Irrigation:135 mm;N:180 kg/hm²;P₂O₅:126kg/hm²;K₂O:37.1 kg/hm²?.The rangeability of yield,biomass,and harvest index of each varieties were decided by varieties.In general,yields of Xinong979 and Xinong165 are better,and that of Shaanmai139 are worse.Therefor,planting Xinong979 and Xinong165 at the high level of water and fertilizer will achieve the maximum yield which are 8125 kg/hm² and 8087 kg/hm².?4?Water and fertilizer amount and variety have significant effects on nitrogen,phosphorus use efficiency and absorption of nitrogen,phosphorus and potassium of wheat.Variety also has significant effect on water use efficiency and potassium use efficiency.Increasing the amount of water and fertilizer can increase absorption of nitrogen,phosphorus and potassium,but it will lead to the decrease of nitrogen and phosphorus use efficiency.There are significant differences in water use efficiency,absorption and use efficiency of nitrogen,phosphorus and potassium between different varieties.The use efficiency of water,nitrogen,phosphorus and potassium of Xinong165 and Xinong979 are better.