Agronomic and Genetic Analysis of Tarnished Plant Bug Tolerance in Cotton

We investigated at Stoneville, Miss., in 1973, the effects of heavy and light infestations of tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), on six genetic populations of cotton, Gossypium hirsutum L. Mustard Brassica juncea (L.) Czern, planted in rows adjacent to cotton, was used to attract and accumulate large numbers of plant bugs. The light infestations of plant bugs were maintained by six early-season insecticide applications. The genetic populations used were ‘Stoneville 213,’ ‘Coker 201,’ their reciprocal F₁ and F₂ hybrids, and the reciprocal F₁ backcrosses to the recurrent parents. Lint yield, six yield components, and five fiber properties were determined for plants harvested on four dates: September 12 and 21, October 4, and November 9. The presence of plant bugs resulted in more terminal damage on small plants, and higher lint percentage and decreased boll size and seed/boll on mature ones. Plant bugs had no effect on seed index, lint index, and fiber properties. The reduced number of bolls/plot caused by plant bugs resulted in decreased lint yields. Lint yield and bolls/plot of the more tolerant cultivar (Stoneville 213) were not appreciably reduced by plant bugs until the last harvest. However, in the less tolerant cultivar (Coker 201) yield and number of bolls/plot were reduced most in the first two harvests. No reciprocal genetic effects were detected for any characteristic in this study. An analysis of generation means indicated that additive gene action and additive Χ additional epistasis, were both significant in accounting for terminal damage. Analyses of generation means for lint yield and bolls/plot indicated that additive gene action was responsible for conferring tolerance to plant bugs. No dominance or epistatic effects involved in tolerance to plant bugs were detected. Once the plants had recovered from the early-season plant bug damage, significant dominance for late-season production was detected.