Source‐to‐Sink Manipulation Effects on Cotton Fiber Quality

Abstract

AbstractCotton (Gossypium hirsutum L.) fiber quality varies considerably among years and locations depending on the prevailing environmental conditions. These environmental conditions often affect the assimilate source/reproductive sink ratio of the developing crop. This study investigated the effects of various source‐sink manipulations on cotton fiber quality at various times during the growing season. In 1991 and 1992, field studies were conducted in which six source‐sink manipulation treatments (partial defruited, partial leaf pruned, reflectors, open canopy, shaded plot, and an untreated control) were imposed on the cotton genotypes ‘DES 119’, ‘DPL 5690’, and ‘Prema’. Blooms at anthesis were tagged on four dates each year, and the seed cotton was harvested when these bolls had opened. This seed cotton was then ginned, and fiber quality traits were determined. The shaded plot treatment reduced fiber strength 6% compared with the control. Fiber from the shaded plot treatment was about 2% longer than the control when the shade was applied within the first 7 d of fiber development. The micronaire value was decreased 7% from the control when the shade was applied during the period of fiber development when the fiber secondary cell wall is being deposited. The partial defruited treatment consistently produced about 8% greater micronaire than the control. Fiber from the partial leaf pruned and shaded plot treatment (low source‐to‐sink ratio) averaged 11% lower micronaire than the open canopy and partial defruited treatment (high source‐to‐sink ratio) on the first tagging date. On the third tagging date, fiber maturity, a component of micronaire, for the partial defruited treatment was 6% greater than the control. None of the treatments significantly altered fiber elongation or perimeter. These data indicate that alterations in the light intensity or carbon assimilate supply can affect the quality of cotton fiber produced, particularly fiber strength and micronaire.