关键词: 棉花, 化学封顶, 氮肥, 干物质积累量

Abstract: This paper used ‘Xinluzao 57’ as material, and studied the effects of different nitrogen application rates (0, 100, 200, 300, 400 kg·hm^-2) on the nutrient accumulation and distribution of cotton between chemical topping and manual topping. The results showed that: when the nitrogen application rate reached 300 kg·hm^-2, the aboveground accumulation of dry matter and nitrogen in the chemical topping  still increased slightly, while  decreased in the manual topping. In the chemical topping treatment, the rapid accumulation period of dry matter was 59~109 d after emergence, while was 56~100 d in the artificial topping after emergence. In the late growth stage of cotton (30~60 d after topping), the aboveground dry matter accumulation and nitrogen accumulation in chemical topping were higher than that in manual topping  under the same nitrogen application rate. The optimum nitrogen application rate was 300 kg·hm^-2, the number of bolls per plant was significantly increased by 0.66~1.66, with an average yield increase of 26.72%.

Key words: cotton, chemical toppping, nitrogen fertilizer, dry matter accumulation