Effect of Nitrogen Application Rate on Yield and Nitrogen Use Efficiency of WheatCotton Double Cropping in the Henan Cotton Region

Dong Helin;Li Pengcheng;Liu Aizhong;Liu Jingran;Li Yongqi;Wang Xiaoru;Wang Gang;Institute of Cotton Research of Chinese Academy of Agricultural Sciences/State Key Laboratory of Cotton Biology;

Henan cotton region;;wheat-cotton double cropping;;nitrogen application rate;;yield;;nitrogen fertilization use effi-ciency

To study the effects of nitrogen application rate on yield and nitrogen use efficiency(NUE) of the wheat-cotton double cropping system in the Henan cotton region, we conducted two field experiments in Shangqiu city and Neihuang County, Henan Province. The result showed that wheat yield, total effective spike numbers and grains per spike increased significantly with nitrogen application rate. However, the 1000-grain weight decreased. Maximum wheat yield was obtained at nitrogen application rates of 201.4 kg·hm-2and 187.2 kg·hm-2at the two experimental sites, respectively, whereas optimum yield was at rates of 163.0 kg·hm-2and 134.9 kg·hm-2. With increasing nitrogen application rate, cotton yield and boll numbers per plant also increased significantly. An optimal nitrogen application rate was favorable for improving boll weight. Maximum cotton yield was achieved at nitrogen application rates of 244.4 kg·hm-2and 224.2 kg·hm-2in the city of Shangqiu and in Neihuang County, respectively, whereas optimum cotton yield was at rates of 225.9 kg·hm-2and 207.0 kg·hm-2. The highest NUE in wheat was attained at the nitrogen application rate of 180 kg·hm-2. At the Shangqiu experimental site, total NUE in the wheat-cotton double cropping system declined with increasing nitrogen application rate. However, highest total NUEs were obtained at the rate of 390 kg·hm-2at the Neihuang County site. With increasing nitrogen application rate, both nitrogen partial factor productivity and agronomic efficiency in wheat and cotton decreased.