Abstract: To investigate the effects of different exogenous substances on defoliation ripening, yield and quality of cotton after chemical topping, Xinluzao 67 was planted according to field experiment in Dafeng town (Hutubi county, Xinjiang) . After chemical topping, three doses of exogenous substances were sprayed on the leaf, including dimetyl piperidinum chloride (DPC, 75, 150, 225 g·hm^-2), uniconazole S-3307 (S-3307, 150, 300, 450 g·hm^-2), brassicin (BR, 0.375, 0.75, 1.125 g·hm^-2) and gibberellic acid (GA, 150, 300, 450 g·hm^-2), while water treatment was for control. The seed cotton yield was investigated and the cotton fiber quality was analyzed. The results showed that spraying of different exogenous substances afer chemical topping had an enhanced effect on cotton leaf-stripping and wadding, and the leaf-stripping and wadding rates were increased by 5.05%~17.59% and 11.61%~32.87%, respectively, compared with  CK, which had an influence on the hanging twig rate but not significant. The medium dose (0.75 g·hm^-2) of BR had the best defoliation effect, and the defoliation rate reached 95.33%. The ripening effect was the best in low dose of BR (0.375 g·hm^-2), and the wadding rate reached 98.11%. All treatments had  significant effects on cotton yields and qualities. BR treatment with medium dose (0.75 g·hm^-2) had the highest seed cotton yield, which was significantly increased by 19.27% compared with CK. GA treatment with medium dose (300 g·hm^-2) had the best performance in fiber quality. Medium and low doses of BR (0.375~0.75 g·hm^-2) and medium and low doses of GA (150~300 g·hm^-2) could enhance the effects of defoliation and ripening after chemical-toped cotton, effectively increase the seed cotton yield and optimize the fiber quality of cotton.

Key words: chemical topping, cotton, exogenous substance, defoliation rate, boll opening rate, production

摘要： 为了探究化学打顶条件下，不同外源物质对棉花脱叶催熟和产量品质的影响，以新陆早67 号为材料，于2019 年在新疆呼图壁县大丰镇进行田间试验，采用裂区区组试验设计，于化学打顶后叶面喷施3种剂量的4种外源物质：缩节胺（75、150和225 g·hm^-2）、烯效唑（150、300和450 g·hm^-2）、芸苔素（0.375、0.75和1.125 g·hm^-2）和赤霉素（150、300和450 g·hm^-2），以清水为CK处理，调查不同处理棉花的脱叶率、吐絮率及产量和品质性状。结果表明，在化学打顶基础上喷施不同外源物质均对棉花的脱叶吐絮有增效作用，脱叶率和吐絮率分别较CK提高了5.05%~17.59%和11.61%~32.87%，对挂枝率的影响不显著。中剂量芸苔素处理（0.75 g·hm^-2）的脱叶效果最好，脱叶率达到95.33%；低剂量芸苔素处理（0.375 g·hm^-2）的催熟效果最佳，吐絮率达到98.11%。各处理对棉花产量及品质均有显著影响，中剂量芸苔素处理（0.75 g·hm^-2）的籽棉产量最高，较CK显著提高了19.27%；中剂量赤霉素处理（300 g·hm^-2）的棉花在纤维品质方面表现最佳。中、低剂量的芸苔素处理（0.375~0.75 g·hm^-2）和中、低剂量的赤霉素处理（150~300 g·hm^-2）可以对化学打顶后棉花的脱叶催熟起到增效作用，有效提高棉花籽棉产量，对棉花纤维品质的优化效果较好。

关键词: 化学打顶, 棉花, 外源物质, 脱叶率, 吐絮率, 产量