改善根际土壤环境以及促进棉花根系发育对棉花健康生长及产量和品质的提高意义重大。为探究氮肥减量配施壳寡糖促进棉花根系生长及调节土壤酶活性的作用，以盆栽试验和田间小区试验为研究方法，设置了不施肥、常规施肥(施N 400 kg/hm2、P2O5 140 kg/hm2、K2O 130 kg/hm2)、常规减氮20%施肥、常规减氮20%施肥+聚合度2~6型壳寡糖450 g/hm2、常规减氮20%施肥+聚合度2~20型壳寡糖450 g/hm2等5个处理，研究了氮肥减量配施不同聚合度类型壳寡糖对棉花根系生长和根际土壤酶活性的影响。结果表明，除土壤过氧化氢酶外，2个配施壳寡糖的处理均不同程度上降低了土壤脲酶、蔗糖酶、磷酸酶活性，其中酶活性降幅最大的为土壤磷酸酶，常规减氮20%施肥配施聚合度2~6型壳寡糖处理和常规减氮20%施肥配施聚合度2~20型壳寡糖处理分别比常规减氮20%施肥处理降低10.6%和5.5%。常规减氮20%施肥配施聚合度2~6型壳寡糖处理较常规减氮20%施肥处理土壤硝态氮含量增加了38.1%，而常规减氮20%施肥配施聚合度2~20型壳寡糖处理较常规减氮20%施肥处理土壤硝态氮含量降低了43.4%。并且施加聚合度2~6型、聚合度2~20型2种不同聚合度类型壳寡糖后，棉花根长较常规减氮20%施肥处理分别增加64.2%、40.1%，根表面积较常规减氮20%施肥处理增加74.8%、54.4%，根体积较常规减氮20%施肥处理增加106.2%和73.2%。由此可见，聚合度2~6型壳寡糖对促进棉花根系生长效果要优于聚合度2~20型壳寡糖。

Improving the rhizosphere soil environment and promoting the development of cotton roots are of great significance for the healthy growth, yield, and quality of cotton. To explore the effect of reduced nitrogen fertilizer application combined with chitosan oligosaccharide on promoting cotton root growth and regulating soil enzyme activity, a pot experiment and field plot experiment were conducted. Five treatments were set, i.e., no fertilizer, conventional fertilization(N 400 kg/ha, P2O5 140 kg/ha, K2O 130 kg/ha), 20% nitrogen reduction fertilization, 20% nitrogen reduction fertilization+450 g/ha chitosan oligosaccharide with a degree of polymerization of 2 to 6, and 20% nitrogen reduction fertilization+450 g/ha chitosan oligosaccharide with a degree of polymerization of 2 to 20. The effects of nitrogen fertilizer reduction combined with chitosan oligosaccharide with different degree of polymerization on cotton root growth and rhizosphere soil enzyme activity were studied. The results showed that, except for soil catalase, the two chitosan oligosaccharide treatments reduced soil urease, sucrase, and phosphatase activities to varying degrees. The largest decrease was observed in soil phosphatase activity, with reductions of 10.6% and 5.5% compared to the 20% nitrogen reduction treatment, for the 2 to 6 and 2 to 20 degree polymerization chitosan oligosaccharide treatments, respectively. The 2 to 6 degreepoly merization chitosan oligosaccharide treatment increased soil nitrate nitrogen content by 38.1% compared to the 20% nitrogen reduction treatment, while the 2 to 20 degree polymerization chitosan oligosaccharide treatment decreased soil nitrate nitrogen content by 43.4%. Additionally, the 2 to 6 and 2 to 20 degreepoly merization chitosan oligosaccharide treatments increased cotton root length by 64.2% and 40.1%, root surface area by 74.8% and 54.4%, and root volume by 106.2% and 73.2%, respectively, compared to those in the 20% nitrogen reduction treatment. These findings indicate that chitosan oligosaccharide with a degree of polymerization of 2 to 6 is more effective in promoting cotton root growth than that with a polymerization degree of 2 to 20.

S562；S147.2

新疆维吾尔自治区重点研发计划项目(2022B02053-2)； 塔里木大学校长基金创新团队项目(TDZKCX202301)。