Ethephon ripening affects boll weight and fiber quality of machine-harvested cotton.

The use of ethephon can achieve early and concentrated the machine-harvested cotton boll opening. The purpose of this study is to analyze the effect of the boll-period shortening on the boll weight, fiber quality, and relationship, when the ethephon was sprayed at different stages of the boll development with a selection of 18 materials. The results showed that when the period of cotton was 47--69 days, spraying ethephon at the age of boll was 40.5--49.7 days, which could advance boll opening by 3.5--5.7 days. It took 64.1--69.7 days for fiber to fully mature under ethephon, while it took 54.8--60.5 days for cotton seed. When boll was opened 1.5--6.2 days earlier, the probability of boll weight and fiber quality decreasing was up to 58.0%--76.5%. To achieve an early opening of the boll, ethephon can be applied at the boll age of 34.8--44.1 days, when the boll weight (< 0.26 g) and fiber quality damage (length reduction < 0.28 mm and fiber strength < 0.30 cN tex--1) at the top of cotton plant are reduced by 5% and 1%, respectively. In addition, the boll period was shortened in some materials, but the boll weight, fiber length, and strength were increased, with the 9.5%--23.5% probability. Therefore, the reasonable use of ethephon in some cotton varieties can shorten the boll period and improve the boll weight and quality. [ABSTRACT FROM AUTHOR]