ABSTRACT
The greatest yield limiting factor for cotton production on the Texas High Plains is the lack of an adequate water supply throughout the growing season. A majority of the growing season rainfall is received as short duration and high intensity thunderstorms which increase the risk of intermittent yet often severe periods of water stress. Early season water stress reduces lint yields by reducing fruiting site production. Management of plant density offers the only opportunity to reduce the risk of water stress under rainfed conditions by matching plant numbers per unit area to the expected water supply. Field experiments were conducted in 1991 and 1992 to determine the effects of the plant density-water supply interaction on fruit production, retention, and final size. Treatments included plant densities of 5, 10, 15, and 20 plts m-2 and irrigation levels of 0, 50, and 100% ETa replacement. Boll number and weights were determined at every position-by-node site. Bolls M-2 accounted for 87% of the variability in yields that ranged from 8.7 to 145 kg-lint per M2. First position fruit numbers increased at the greatest rate as water supply increased, followed by second and third position fruit numbers. Final boll size of first and second position fruit increased as water supply per plant increased whereas third position boll weights remained constant. Boll retention was unaffected by water supply or plant density.
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