Influence of Longevity of Use on Cotton Cultivars' Performance1

The objective of this study was to determine whether continued use of cotton (Gossypium hirsutum L.) cultivars over 8 to 12 years markedly affected performance. The four cultivars and the year the seed of each was received for evaluation trials were ‘Coker 201’, 1967, 1971, and 1976; ‘Coker 310’, 1969, 1972, and 1976; ‘Stoneville 213’, 1965, 1971, and 1976; and ‘Deltapine 16’ 1967, 1972, and 1976. Seed of the 12 cultivar‐age versions were all produced at Stoneville, Miss. in 1976. In 1977, evaluation trials were grown at two locations each in South Carolina and Mississippi. Cultivars constituted whole plots and the three age versions of each cultivar constituted sub‐plots. Six replications were used in all studies. No significant differences among age versions were detected for lint yield, 50% fiber length, and fiber strength for any cultivar. However, certain small but statistically significant differences were detected for lint percentage, boll size, seed index, 2.5% fiber length, elongation, and micronaire. No evidence of major changes in cultivar performance with increasing age of the cultivar was detected. Apparently, such factors as inbreeding depression, seed contamination, reselection within a cultivar, and accumulation of seed carrying pathogens were not major problems in the maintenance of cotton cultlvars. Commercial companies appear to have effectively maintained the purity and characteristics of these esablished cotton cultivars.