UPTAKE OF SULFUR BY 4 COTTON CULTIVARS GROWN UNDER FIELD CONDITIONS

There has never been an intensive study of the sulfur (S) nutrition of cotton (Gossypium hirsutum L.) when grown under field conditions. Field studies were conducted on two non-irrigated soils to evaluate the S-uptake characteristics of four selected cotton cultivars that are representative of those produced in the Southern United States. Four cultivars with diverse genetic backgrounds, Deltapine 90, Coker 315, Paymaster 145, and Stoneville 825 were grown on a Norfolk fine sandy loam (fine loamy, siliceous, thermic, Typic Kandiudults) and a Decatur silt loam (clayey, kaolinitic, thermic, Rhodic Paleudults). Whole plants were collected at two-week intervals over the growing season starting at 15 days after planting. The plants were partitioned into leaves, stems, burs, seed, and lint, and analyzed (except for lint) for S. Total S uptake when averaged over both soils and all four cultivars was 20.4 (+/-9.4) kg/ha [or 2.7 (+/-0.7) kg S per 100 kg lint produced]. Sulfur uptake on the Norfolk soil (15.6 (+/-8.5) kg/ha) was lower compared to the Decatur soil [25.1 (+/-7.9) kg/ha]. There were no cultivar differences in total S uptake on the Norfolk soil, but total S uptake on the Decatur soil was affected by the interaction between sampling date and cultivar. The concentration of S and S uptake by some plant parts were affected by the interaction between sampling date and cultivar, however, cultivar differences were not consistent among soils or over the growing season. Maximum daily accumulation of S occurred during the final two week sampling period at the end of the growing season (cumulative heat unit 1193-1444) during which an average of 29.5% of the total S was accumulated.