Inheritance of grain mold resistance in grain sorghum without a pigmented testa
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abstract
The improvement of grain mold resistance in sorghum [Sorghum bicolor (L.) Moench] has been difficult, presumably because of the complex inheritance of the trait. The objective of this study was to determine the inheritance of grain mold resistance by generation means analysis. The F1, F2, and backcross generations of a cross between 'Sureo' (a dual-purpose food grain and forage variety, resistant to grain mold) and 'RTx430' (a widely adapted inbred line, highly susceptible to grain mold) were evaluated in eight different field environments. Significant differences ha grain mold incidence between the generations evaluated ha this study were observed in all environments. Combined analysis detected a significant generation five-environment interaction indicating that the genotypes reacted differently to each environment. Generation means analysis of transformed grain mold scores detected additive effects in all eight environments, and dominance effects were detected in seven of eight environments. Epistatic effects were detected in only two of eight environments, but combined analysis indicated that higher order interactions were important when evaluated across environment. Broad-sense heritability estimates ranged from 0.46 to 0.82, while narrow-sense heritability estimates ranged from 0.39 to 0.59. At least four to 10 genes were estimated to contribute to grain mold resistance. The results of this study indicate that selection in specific environments is useful for enhancing resistance to mold in these environments, but it may not be as effective in providing grain mold resistance across a wide range of environments.
