Full-season interference and soil water relations of silverleaf nightshade (Solanum elaeagnifolium) with upland cotton (Gossypium hirsutum)

Abstract

Full-season interference of silverleaf nightshade (Solanum elaeagnifolium Cav. #1 SOLEL) with upland cotton (Gossypium hirsutum L. 3 'Paymaster 145') was evaluated in five field experiments during 1984 and 1985. The experiments were established in dryland and irrigated environments at weed densities ranging from 0 to 32 plants/10 m of crop row. Dry weight of silverleaf nightshade increased from 0.08 to 0.39 kg/plot for each additional weed/10 m of row. Intraspecific competition among weed plants was not evident. However, cotton plant height was reduced at weed densities of 4 plants/10 m of row and above. When compared to cotton grown under weed-free conditions, the threshold densities at which initial lint yield reductions occurred ranged from 4 to 32 weed plants/10 m of row under the five environments. Irrigated cotton more effectively competed with the weed than did dryland cotton suggesting that moisture is one of the primary competition factors between this crop and weed. The lin~ yield component, boll size, was reduced at densities of 2 weeds/10 m of row and above. Silverleaf nightshade reduced mechanical harvest efficiency only at the 16- and 32-weed densities. Fiber properties were not affected by the weed. A regression model predicted t~at lint yield reduction would be approximately 1.54% for each silverleaf nightshade plant/10 m of cotton row. Within the 0 to 30 cm range, the distance silverleaf nightshade was established from the crop row did not affect the weed's interference with cotton. Aciditional index words, Competition, weed biomass, crop height, lint yield, boll size, harvest efficiency, fiber quality, predictor model, distance from row, SOLEL.