Water efficient utilization of ‘Xiaoyan 60’ winter wheat under different water and nitrogen conditions

Scarcity of freshwater resources is an important factor that limits crop yield in the Bohai Rim in Hebei Province. Appropriate fertilization increases crop water use efficiency and meets demand for nutrient of crops. A pot experiment was conducted to study the effects nitrogen and water on winter wheat in Nanpi Agro-Ecosystem Experimental Station, Chinese Academy of Sciences (11640′E, 3800′N, altitude 1.0 m). Three water levels 50% (W0), 65% (W1) and 80% (W2) of field capacity, four nitrogen levels 0 g(N)·kg^-1 (N0), 0.10 g(N)·kg^-1 (N1), 0.20 g(N)·kg^-1 (N2) and 0.29 g(N)·kg^-1 (N3) were respectively set in the pot experiment, and the combinations assessed in a total of 12 experiment treatments. Each treatment was repeated 10 times. The variations in dry matter accumulation and distribution and photosynthetic parameters of winter wheat ‘Xiaoyan 60’ were analyzed. As expected, water and nitrogen significantly increased biomass, grain yield, leaf chlorophyll, leaf water potential, leaf photosynthetic rate and water use efficiency (WUE) of ‘Xiaoyan 60’. The effect of water on winter wheat yield was greater than that of nitrogen. Compared with water and nitrogen deficit (W1N1) treatment, yield increased by 66.03% for the treatment with appropriate water and nitrogen (W2N2). Yield under W1N1 was 153.30% higher than that under severe water and nitrogen deficiency (W0N0). At the same water level, SPAD increased with increasing nitrogen dose. Then at the same nitrogen level, SPAD was lower under severe water stress (W0) and suitable water (W2) treatments than under mild water stress (W1) treatment. Water had a positive effect on leaf water potential, which significantly increased from W0 to W1 but with not obviously increased from W1 to W2. Photosynthetic rate (P_n), transpiration rate (T_r) and instantaneous water use efficiency (WUE_i) increased with increasing N dose. P_n and T_r improved and WUE_i decreased with increasing soil moisture. Yield and yield water use efficiency (WUE_y) increased with increasing water content from W0 to W1 and then remained unchanged from W1 to W2 under N1 or N0 conditions. WUE_y of winter wheat under N2 and N3 conditions increased with increasing water content. In conclusion, 1) proper management of water and nitrogen maintained ‘Xiaoyan 60’ grain yield and water use efficiency (WUE) at high levels. Excessive water and nitrogen use decreased grain yield and WUE. 2) Grain yield, WUE and leaf photosynthetic rate were positively correlated with water and nitrogen. 3) ‘Xiaoyan 60’ was more suitable for production at low water and medium fertilizer conditions in the Bohai Rim of Hebei Province.