Effects of Nitrogen Application Rate on Water Consumption Characteristics and Grain Yield in Rainfed Wheat

Abstract

Nitrogen management plays a key role in high yield of rainfed wheat.To propose a suitable nitrogen application rate for the rainfed wheat in Yellow and Huaihe River Valleys,particularly in Shandong Province,we explored the water consumption characteristics and final yield of dryland wheat in response to different nitrogen application rates in the 2009–2010 and 2010–2011 growing seasons.Wheat cultivars Jimai 22(in 2009–2010 growing season)and Shannong 16(in 2010–2011 growing season)were both supplied with nitrogen fertilizer at 0(N0),90(N1),120(N2),150(N3),180(N4),and 210 kg ha-1 (N5).In N3 treatment,the water consumption amount had no significant difference with that in N1 or N2 treatment from sowing to jointing stage,but significantly higher from jointing to maturity stage.The water consumption amounts in N4 treatment had no significant changes at various stages,and increased significantly in N5 treatment from revival to anthesis stage.When the nitrogen application rate was raised from 90 to 150 kg ha-1 ,wheat showed an increased capability to absorb soil water from deep soil layers.However,further increase of nitrogen fertilizer had no effect on consumption amount of soil water below 80 cm from the surface.The soil evaporation after jointing was significantly lower in N3 treatment than in N1 and N2 treatments,and the water use efficiency of flag leaf after anthesis was significantly higher in N3 treatment than in N1 and N2 treatments.Compared to N3 treatment,N4 and N5 treatments had no significant effects on soil evaporation after jointing and water use efficiency of flag leaf after anthesis.Therefore,150 kg ha-1 is proposed as the optimal nitrogen application rate for rainfed wheat grown in the environment similar to that in this experiment,because N3 treatment resulted in the highest grain yield and water use efficiency,as well as relatively high nitrogen productive efficiency.