Influence of early defoliation on cotton yield, seed quality, and fiber properties

Abstract

Abstract Chemical defolliation of cotton ( Gossypium hirsutum L.) should be carried out when all plant processes are complete. However, initiating defoliation treatment prior to this time of plant development is necessary in most instances. The objective of this research was to determine the influence of chemical defoliant of yield components, fiber quality and seed quality of an early-maturing cotton cultivar when applications were made at 20, 40, 60, or 80% open bolls. Yield loss occurred when defoliants were applied at 20 and 40% open bolls. However, there was no evidence to indicate that applications made at 60% or greater resulted in yield loss or lower quality of the fiber. Increases in fiber strength and length were observed when defoliants were used at 20% open bolls. This was attributed to the physiological abscission of younger bolls, leaving a higher percentage of older, more mature bolls containing fiber of greater length and strength. In general, defoliant treatments should not be applied prior to 60% open bolls in order to safeguard against potential losses in yield and undesirable changes in fiber quality. Yield losses and quality reductions occurred due to improper timing, irrespective of defoliant used.