Response of water use of winter wheat at different growth stages tonitrogen fertilizer and water-retaining agent

A field experiment was conducted to determine the water use characteristics of winter wheat at different growth stages under application of water-retaining agent (60 kg·hm ^-2) and nitrogen fertilizer 0, 225 kg(N)·hm^-2, and 450 kg(N)·hm ^-2. The field experiment investigated soil moisture, winter wheat biomass accumulation, water use at different growth stages as affected by wa-ter-retaining agent and nitrogen fertilizer. The results indicated that soil moisture, biomass accumulation, yield and water use effi-ciency (WUE) of winter wheat increased after water-retaining agent and nitrogen fertilizer application. Compared with other treat-ments, soil moisture under treatments of 450 kg(N)·hm ^-2 of nitrogen fertilizer, 60 kg·hm ^-2 of water-retaining agent, and 60 kg·hm^-2 of water-retaining agent plus 450 kg(N)·hm ^-2 nitrogen fertilizer increased. There was a significant increase in the accumulation of above-ground winter wheat dry-matter with increasing nitrogen application rate without water-retaining agent. However, winter wheat dry-matter accumulation decreased under water-retaining agent plus excessive nitrogen fertilizer treatment. Winter wheat dry-matter biomass increased from jointing to harvest and the increase was more obvious at the later growth stage under wa-ter-retaining agent with 225 kg(N)·hm^-2 nitrogen fertilizer treatment. From sowing through jointing, booting and grain-filling stages, WUE was boosted by increased nitrogen fertilizer application rate. WUE increased significantly under water-retaining agent plus nitrogen fertilizer treatment. Also from grain-filling to harvest, WUE increased by 53.8% and 57.8% over the control (CK) under 450 kg(N)·hm^-2 nitrogen fertilizer and water-retaining agent plus 225 kg(N)·hm^-2 nitrogen fertilizer treatments, respectively. In conclu-sion therefore, the yield and WUE of winter wheat increased and with the best effect under 60 kg·hm^-2 water-retaining agent plus 225 kg(N)·hm^-2-2 nitrogen fertilizer application.