Heritability of Tolerance to Soybean Cyst Nematode in Soybean

Abstract

Tolerance to Heterodera glycines Ichinohe, soybean cyst nematode (SCN), has recently been identified as an additional control strategy to limit yield losses in soybean, Glycine max (L.) Merr. Heritability estimates are necessary for determining breeding strategies to increase tolerance to SCN. The objectives of this study were to determine the heritability of tolerance in three soybean crosses and determine the degree of association between tolerance and seed yield in untreated and nematicide‐treated plots. A tolerance index (TI) was calculated using the formula: (seed yield of untreated subplot ÷ seed yield of nematicide‐treated subplot) ✕ 100. Fifty‐four F2‐derived lines in the F4 and F5 generations and parents were evaluated for TI in SCN‐infested soil for 2 yr at two locations. The Athens, GA location was infested with SCN Race 3 and Waynesboro, GA with SCN Race 4. Heritability for TI averaged 19% based on variance component estimates (three replications and two locations) and 26% for realized estimates (selection of top 11% of lines based on two‐location means). There was a positive association between TI and seed yield in untreated subplots (r = 0.78 to 0.90), but there was an inconsistent association between TI and seed yield in nematicide‐treated subplots. The variance component estimates of heritability for seed yield in untreated subplots averaged 31% (three replications and two locations). These results indicated that susceptible genotypes can be evaluated for seed yield without nematicides in SCN‐infested soil in the early phases of a breeding program to increase tolerance.