Inheritance of resistance to pendimethalin herbicide induced stem damage in soybean

Selective herbicides are valuable weed control tools; however, selectivity is not always complete, resulting in crop damage. Stem breakage, lodging, and enlarged hypocotyls (brittle bean syndrome) limit yields of soybean [ Glycine max (L.) Merr.] genotypes treated with pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro benzenamine]. Developing genotypes with resistance to pendimethalin injury would eliminate or reduce this problem. Genetic studies were conducted to determine the inheritance of resistance to pendimethalin induced stem damage. The F-2:3 progeny of crosses involving resistant ('Asgrow A4715' and 'Flyer') and susceptible ('Essex' and K87-7-95) genotypes were screened in a greenhouse. Each genotype was treated with 1.68 kg ha(-1) pendimethalin preemergence and irrigated as needed. Plants were scored at V4 for stem breakage. Progeny distributions indicated that resistance to brittle bean syndrome damage behaved as a quantitative trait. Dominance for stem breakage was expressed in the population of A4715 x Essex. Flyer was more sensitive to herbicide damage than Asgrow A4715 because it has fewer genes for resistance or different alleles. The F-2:3 variance component heritability estimates ranged from 0.19 to 0.52. Gain from selection for resistance to pendimethalin injury is possible, and resistant progeny can be recovered from segregating populations.