Cotton (Gossypium hirsutum) and Palmer amaranth (Amaranthus palmeri) development as influenced by Palmer amaranth competition

Abstract

Research was conducted to determine the influence of phics. Palmer amaranth (Amaranthus palmeri S.Wats.) competition on cotton (Gossypium hirsutum L.) growth and development in Central Texas. Growth and development of both species were measured throughout the cotton-growing seasons of 1996 and 1997. The cotton variety was Delta and Pineland 50, commonly grown dryland variety by central Texas area producers. The cotton was planted at 1 62,000 seeds per ha and the Palmer amaranth at 0, 1 , 2, 3, 4, 6, 8, 10, and 12 plants per 9. 14 m of row. Cotton canopy was not significantly altered by competition with Palmer amaranth. Cotton shoot biomass at mid-season was erratically affected by 1, 2, 3, 4, and 6 Palmer amaranth per row, however, densities exceeding 6 Palmer amaranth plants per row significantly decreased cotton shoot biomass by greater than 35%. Cotton plants 25, 75. and 1 25 cm away from a Palmer amaranth plant.were mapped for total boll set and boll position Total number of bolls and position of bolls were not significantly influenced by Palmer amaranth at any of the distances. Palmer amaranth densities exceeding 3 Palmer amaranth plants per row significantly reduced cotton lint yields by 25%. . Cotton lint qualities, including micronair, length, strength, and uniformity, were not significantly reduced by Palmer amaranth at any of the densities. Palmer amaranth canopy development was not influenced at the Palmer amaranth densities evaluated. Palmer amaranth mid-season shoot biomass was significantly larger when Palmer amaranth densities exceeded 6 versus 0 Palmer amaranth plants per row. By the end of the season, the Palmer amaranth biomass maintained a trend similar to the mid-season biomass. However, the end of the season biomass pooled over years fit a positive linear equation of y = 545x + 650. Intraspecific competition was not evident in Palmer amaranth canopy development or biomass accumulation at the densities of Palmer amaranth evaluated in this experiment.