Seed Damage by Pink Bollworm to Race Stocks, Cultivars, and Hybrids of Cotton
1978
Wilson, F. D. | Wilson, R. L.
Noncultivated race stocks of cotton (Gossypium hirsutum L.) previously selected via diet bioassays for antibiosis to pink bollworm (Pectinophora gossypiella Saunders), were field-tested for resistance along with cultivars and race stock ✕ cultivar F₁ hybrids. No race stock or hybrid was consistently more resistant than the cultivars in 1975. In 1976, one race stock, Texas 40, and two hybrids showed some resistance. The general lack of resistance in the field among race stocks previously selected for antibiosis in diets was disturbing but not necessarily unexpected because the two types of tests might have measured different facets of resistance. Results showed the need for a more direct measure of antibiosis in diet-selected stocks, such as placing larvae on bolls of live plants. Genetic differences in hybrids were attributed to differences among their race-stock parents. Race stock ✕ harvest-date interactions in both years, and cultivar ✕ harvest-date interactions in 1975 were caused by hybrid combinations in which seed damage by pink bollworm increased at different rates. Gene action was presumably primarily additive because cultivar ✕ racestock interactions were nonsignificant and because most hybrid/harvest-date combinations did not differ from the midparent (MP). One hybrid array deviated consistently from MP in the direction of increased seed damage and one deviated in the opposite direction. Correlations between seed damage and six agronomic characters showed no consistent pattern.
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