Effects of Removal of Redundant Buds and Topping of Fruiting Branches on Source-Sink Activity,Yield, and Fiber Quality of Cotton

Objective] Removal of redundant buds and decapitation of fruiting branches are important pruning measures for cotton production. The effects of the two procedures on source–sink activity, yield, and fiber quality were studied to provide a scientific basis for a simplified pruning method. Method] A field trial was carried out in bottomland of the Yellow River valley, Zhengzhou, Henan Province in 2014–2015 using cotton ‘Lumianyan 28’. Treatments consisted of removal of redundant buds, decapitation of fruiting branches, and removal of redundant buds and decapitation of fruiting branches in combination (RDR treatments). Redundant buds and tops of fruiting branches were retained in the control (CK). The source–sink size and activity, yield traits, fiber quality, and economic return were recorded. Result] The RDR treatments increased the leaf area index and total dry matter accumulation, and increased the sink-source ratio at advanced growth stages compared with CK. In the middle growth period, the RDR treatments increased indoleacetic acid (IAA) content and superoxide dismutase (SOD) activity, and decreased abscisic acid (ABA) content in the leaf. Moreover, the RDR treatments increased IAA content and SOD activity, and decreased ABA content in seeds of pre-summer bolls and summer bolls, whereas the IAA and ABA contents and SOD activity in fibers showed the opposite trend to that of seeds. The lint yield following removal of redundant buds, decapitation of fruiting branches, and combined removal of redundant buds and decapitation of fruiting branches was increased by 4.43%, 5.17%, and 9.31%, respectively, but no significant difference was observed among these treatments. Decapitation of fruiting branches had amore marked effect on yield than removal of redundant buds, and these two treatments applied in combination had a cumulative effect on yield. The RDR treatments had no significant effect on fiber quality. Decapitation of fruiting branches increased economic return, but removal of redundant buds reduced economic return, and the effect on economic return of removal of redundant buds and decapitation of fruiting branches in combination was inconsistent. Conclusion] The RDR treatments generally improved the source–sink relationship, enhanced source and sink activity, and increased cotton yield. However, the increase in yield and economic benefits were less marked. We recommend simplified pruning techniques without removal of redundant buds and decapitation of fruiting branches for large-scale cultivation of cotton.