关键词: 棉花, 打顶剂, 喷施时间, 农艺性状, 产量, 品质, 南疆

Abstract: The effects of different topping agents［Tuyouta（flumetralin），Great Wall Brothers（mepiquat chloride）］and spraying time（July 5，July 10，July 15）on agronomic traits，yield and quality of cotton were studied with five main cotton varieties in southern Xinjiang，so as to determine the types and spraying time of topping agents suitable for southern Xinjiang cotton area，and provide theoretical basis for the promotion and application of chemical topping agents in cotton area of southern Xinjiang.The results showed that compared with 1 d after spraying，the plant height of cotton increased by 8.9% and 12.9%，number of fruit branches increased by 27.0% and 22.7%，and number of bolls per plant increased by 2.2 times and 2.8 times，respectively，at 21 d after spraying Tuyouta and Great Wall Brothers on July 5；The plant height of cotton increased by 11.0% and 6.3%，number of fruit branches increased by 8.9% and 12.3%，and number of bolls per plant increased by 3.7 times and 5.4 times，respectively，at 21 d after spraying topping agent on July 10；The plant height of cotton increased by 9.8% and 7.3% respectively，number of fruit branches increased by 12.4% and 22.3% respectively，and number of bolls per plant increased by 2.2 times and 1.4 times respectively，at 21 d after spraying topping agent on July 15.Compared with the treatment spraying Great Wall Brothers，the boll number，lint percentage，seed cotton yield，lint yield，uniformity and breaking strength of the treatment spraying Tuyouta on July 5 increased by 7.0%，2.6%，3.4%，0.40% and 0.7%，respectively；The boll number，seed cotton yield，lint yield，fiber length，uniformity and breaking strength of the treatment spraying Tuyouta on July 10 reduced by 3.11%，10.2%，4.7%，4.0%，0.67% and 3.4%，espectively；The boll number，lint percentage，seed cotton yield，lint yield，fiber length，uniformity and breaking strength of the treatment spraying Tuyouta on July 15 increased by 13.7%，0.4%，9.0%，9.7%，6.8%，0.19%and 4.3%，respectively.By comparing different spraying time，as a whole，it was found that the control effect of spraying topping agens on July 10 on plant height was the best，and the number of bolls per plant，number of bolls，seed cotton yield，lint yield and Micronaire were the highest. The results of cluster analysis showed that spraying Tuyouta was better than spraying Great Wall Brothers，and the best spraying effect was on July 10，followed by July 5.In summary，in the cotton area of southern Xinjiang，spraying topping agents on July 10 can effectively control the plant height of cotton，increase the number of bolls per plant，optimize the spatial structure of cotton，and enhance yield and quality of cotton，especially Tuyouta.

Key words: Cotton, Topping agent, Spraying time, Agronomic traits, Yield, Quality, Southern Xinjiang