Plant bugs, Lygus lineolarius (Palisot de Beauvois) and Neurocolpus nubilius (Say), can delay early fruiting of cotton (Gossypium hirsutum L.), and thus increase risks associated with other cotton insect pests. Injury from plant bugs might be lessened by seeding mixtures of cotton genotypes (blends) rather than pure lines. Our objectives were to evaluate plant bug injury in pure lines and all possible two-component blends of five cotton genotypes and to illustrate the use of diallel analysis for evaluating these blends for plant breeding purposes. Five cotton genotypes, which had distinguishing morphological traits, and 10 blends (all possible two-part combinations of the five genotypes) were evaluated in tests at Marianna, AR, in 1991 and at Clarkedale, AR, in 1991 and 1992. Following plant bug infestation, squares were randomly collected from each plot and evaluated for plant bug injury to anthers. Blending ability for plant bug injury was evaluated using a diallel analysis with the pure lines representing parents and the blends representing the F1 generation. Variation among the genotypes evaluated as pure lines was consistent with previous reports. The diallel analysis indicated significant general blending ability (additive effects) and nonsignificant specific blending ability (nonadditive effects) for plant bug injury in each test. Plant bug injury to blends was intermediate to injury to their respective component genotypes. Blends had no advantage over pure lines of the genotypes with respect to plant bug injury. No synergism was found in the blend of the two most resistant lines. This approach may be an effective method for choosing potential parents in a breeding program that emphasizes host plant resistance.
