[Effects of water-nitrogen combination on dry matter, nitrogen accumulation and yield of winter wheat].

In two growing seasons of wheat (2015-2017), we conducted a field trial with Taishan 28 in Tai'an Academy of Agricultural Science Feicheng experimental base, Tai'an City, Shandong Province. There were four irrigation levels of 150 (A1), 300 (A2), 450 (A3), and 600 (A4) m3·hm-2, and four nitrogen application levels of 90 (B1), 135 (B2), 180 (B3), and 225 (B4) kg·hm-2. We examined the effects of the combination effects of irrigation and nitrogen on dry matter accumulation and transport, nitrogen accumulation and transport, water consumption and utilization, photosynthetic characteristics, wheat grain yield and yield components of wheat. The results showed that dry matter accumulation, nitrogen accumulation, vegetative organs production, storage and the transportation volume to grains of the dry matter and nitrogen, and dry matter and nitrogen accumulation of grain in the mature stage of wheat all reached the maximum in A3B3 treatment, which were significantly different from other treatments. Under all the nitrogen treatments, soil water consumption in the 60-200 cm soil layer was A3>A4>A2>A1. Water use efficiency and nitrogen use efficiency in A3B3 treatment were higher than that under A3B4, A4B3 and A4B4. The net photosynthetic rate, stomatal conductance and transpiration rate of flag leaves from 7 to 28 days after flowe-ring were all significantly higher in A3B3 treatment, which was conducive to the photosynthetic synthesis of carbohydrates in wheat. The interaction effect of water and nitrogen addition significantly affected grain yield and yield components. Wheat yield was the highest in A3B3 treatment which reached at 9400 kg·hm-2. In conclusion, the treatment with irrigation of 450 m3·hm-2 and nitrogen of 180 kg·hm-2 could significantly improve dry matter and nitrogen accumulation, and promote transportation volume of the dry matter and nitrogen to grain. Compared with the high water and nitrogen treatment, it could effectively increase water use efficiency and nitrogen use efficiency, enhance photosynthetic capacity of flag leaf, produce more carbohydrate, and increase grain yield.