Abstract:

To explore the feasibility and supporting techniques of chemical defoliation technology in Liaohe Basin cotton area, the authors chose chemical defoliating agent Xinshaili, set up 2 planting densities, 2 treatment times and 5 treatment methods, and took water treatment as CK. Xinshaili could effectively promote the defoliation and boll opening of cotton. In terms of concentration, moderate concentration (2100 mL/hm²) was recommended for defoliation, while high concentration (2700 mL/hm²) for ripening. The defoliation effect of treating twice (1350 mL/hm²+1350 mL/hm²) was lower than that of once, but the ripening effect was significantly improved. In terms of planting density, the effect of defoliation and ripening of 8.25×10⁴ plants/hm² was better than that of 11.25×10⁴ plants/hm². In terms of treatment time, the effect of defoliation and ripening of treatment on September 5 was more obvious than that on September 15, but the yield was lower. Therefore, the treatment with planting density of 8.25×10⁴ plants/hm² and treatment time on September 15 is suggested for Liaohe Basin cotton area, and the defoliant concentration could be appropriately increased. 2 times treatment is also suggested for some areas with good conditions.

Key words: cotton, chemical defoliant, defoliation rate, boll opening rate, yield, fiber property