Abstract:

The aim is to investigate the effects of nitrogen application at jointing stage on the photosynthetic characteristics and yield of winter wheat under drip irrigation. Under the condition of field drip irrigation, ‘Xindong 41’ was used as the experimental material, and four different nitrogen application treatments [N0 (0 kg/hm ²), N1 (90 kg/hm²), N2 (180 kg/hm²), N3 (270 kg/hm²)] under three different drip irrigation amount [W1 (1500 m³/hm²), W2 (3000 m³/hm²), W3 (3450 m³/hm²)] were conducted to study the effects of different treatments on chlorophyll content (SPAD value), leaf area index (LAI), leaf photosynthetic characteristics and yield of winter wheat. The results showed that the SPAD value of different nitrogen application treatments under three kinds of drip irrigation were all presented a trend of “first increase and then decrease” from jointing to milking stage, the maximum value was at the filling stage. LAI showed “first increase and then decrease” tendency and reached the maximum at booting stage. Under the same nitrogen application level, with the amount of drip irrigation increase, the net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of the leaves increased while the intercellular CO₂ concentration (Ci) decreased. At the low level drip irrigation amount (W1 treatment), increasing the nitrogen application at jointing stage could increase the spike number, grain number per spike, 1000-grain weight, yield and harvest index effectively, but it had adverse effect on yield when the water was sufficient (W2 and W3 treatment). Based on the comprehensive analysis of various yield indicators and nitrogen use efficiency, under the condition of drip irrigation amount of 3000 m³/hm² and the nitrogen application of 180 kg/hm², the winter wheat could obtain relatively high grain yield and maximum nitrogen use efficiency.

Key words: winter wheat, nitrogen application, drip irrigation amount, photosynthetic characteristics, yield