Effects of Reduced Nitrogen Application on Photosynthetic Characteristics and Fluorescence Parameters of Spring Wheat under Drip Irrigation

【Objective】 Drip irrigation technology has been gradually applied to the production of wheat and other closely planted crops due to its advantages of water saving, energy saving, labor saving and fertilization with water. However, there are some problems such as unreasonable nitrogen fertilizer input and low utilization rate. In this study, the effects of nitrogen reduction regulation on photosynthetic characteristics, fluorescence parameters and yield of spring wheat under drip irrigation were studied in the hope of providing a scientific basis for further improving spring wheat yield and nitrogen fertilizer utilization efficiency under drip irrigation in Xinjiang. 【Method】 Random block design was adopted, with nitrogen application amount as the main area and varieties as the secondary area. Using Xinchun 31 and Xinchun 6 as experimental materials, the nitrogen fertilizer applied in the whole growth period was set as 0 kg/hm² (N₀),225 kg/hm² (N₁), 250 kg/hm² (N₂), 275 kg/hm² (N₃), and 300 kg/hm² (N₄). 【Result】 The results showed that during the whole growth period of wheat, with the decrease of nitrogen application amount, the LAI of both varieties reached the maximum value at heading stage and the trend was first increasing and then decreasing. The SPAD value also increased first and then decreased. The change of Pn, Tr and Gs in wheat flag leaves was first increased and then decreased, while the change of Ci was first decreased and then increased, which was contrary to the change of Pn, Tr and Gs. Fv/Fm and Φ PS Ⅱ at flowering period in the maximum and the trend of change was first increasing and then decreasing; The yield of both varieties increased first and then decreased. The number of panicle and the number of grains per panicle increased with the increase of nitrogen fertilizer use, but the 1,000-grain weight increased first and then decreased. Among them, Xinchun 6 had the highest yield under N₂ treatment, and Xinchun 31 had the highest yield under N₃ treatment. Path analysis showed that among the three factors of yield, the number of panicle, grain number of panicle and 1,000-grain weight of both varieties had a great influence on the yield, but the 1,000-grain weight had little effect on the yield. 【Conclusion】 The optimum nitrogen application amount for Xinchun 31 is 275 kg/hm², and the optimum nitrogen application amount for Xinchun 6 is 250 kg/hm².