Harvest Aids Applied at Appropriate Time Could Reduce the Damage to Cotton Yield and Fiber Quality

Abstract

The application of harvest aids is an important prerequisite for the mechanical harvesting of cotton that can effectively reduce the impurity content and improve the picking rate and operating efficiency of machine-picked cotton. However, determining the appropriate spraying time of harvest aids to achieve the synergistic improvement of cotton boll weight and fiber quality is still unclear. In this study, the damage of harvest aids to cotton boll weight and fiber quality as well as its quantitative relationship to cotton boll age were studied through testing different harvest aid compounds and spraying times. The spraying of harvest aids significantly shortened the boll growth period of cotton by 3.60–6.45 d, and concentrated boll opening was beneficial to cotton mechanical harvesting. The boll weight of immature cotton was significantly decreased by 0.63–1.12 g; the fiber strength was significantly decreased by 2.48–2.77 cN·tex−1, and the micronaire value deteriorated. The negative effect on the boll weight and fiber quality was aggravated by the decrease in the ratio of boll age to boll period (Rd/b) during the harvest aid spraying time. When the fiber strength damage was controlled at 1%, the spraying time Rd/b of the harvest aids was 0.77–0.82, and the boll weight loss was also controlled at 5%. Therefore, it is recommended that an Rd/b of 0.77–0.82 be used to balance the contradiction between cotton yield and fiber quality under harvest aid application.