Interference of Unicorn-Plant (Proboscidea louisianica) with Cotton (Gossypium hirsutum)

Full-season interference from unicorn-plant [Proboscidea louisianica(Mill.) Thell. # PROLO] at densities ranging from 0 to 32 weeds/10 m row was measured on weed and cotton (Gossypium hirsutumL. ‘Westburn M′) parameters in three Oklahoma environments. Linear regression models using log10transformations were superior to linear and comparable to quadratic models in estimating the impact of inter- and intraspecific competition. Weed measurements on an individual plant basis were not reliable indicators of interference. Weed dry biomass, ground cover, and seed capsule production/plot generally increased with increasing weed densities. In the three environments, densities of two, four, and eight weeds/10 m row initially reduced cotton plant height. Maximum height reductions averaged 20, 28, and 43% in the three environments but did not detrimentally affect the mechanical harvest of cotton. As unicorn-plant density (expressed in log10units) doubled (within a range of 1 to 32 plants/10 m of row), lint yield reductions ranged from 84 to 146 kg/ha. Maximum lint yield losses averaged 59, 65, and 74% in the three environments. Transforming lint yield/plot to a percentage of that from weed-free plots resulted in a single quadratic equation applicable over environments. Unicorn-plant at the highest weed density reduced fiber fineness, uniformity, and length, but not fiber strength.