COTTON GENOTYPE RESPONSE TO GREEN-MANURED ANNUAL LEGUMES

The use of cool-season annual legume cover crops in cotton (Gossypium hirsutum L.) production as an N source and for erosion control often results in reduced cotton population density. The objective of this study was to determine if genotypic differences exist among available southeastern USA-adapted cotton varieties for performance when grown following green manured annual legumes. In 1988 and 1989, a field experiment was conducted on a Typic Paleudult in which five cultivars were grown following winter fallow or dessicated and disc-incorporated crimson clover (Trifolium incarnatum L. 'Tibbe') and vetch (Vicia villosa Roth 'Cahaba White'). Nitrogen fertilizer was applied at 95 lb N/acre across the entire experiment. Due to poor establishment of vetch in 1989, data were not used following vetch that year. Population density did not differ among cover crops in 1988. In 1989, a cover crop x cultivar interaction occurred with the cotton cultivar Coker 315 having 30% fewer plants following clover than winter fallow. Total seed-cotton yield was not affected by cover crop treatment either year, but maturity was delayed (measured as percent of total yield in the first harvest) both years in cotton grown following cool-season legumes. The results from this study suggest that when using a cool-season annual legume cover crop as a green manure, cultivar selection criteria do not need to be modified.