| Popis: |
The improvement of grain mould resistance in sorghum (Sorghum bicolor) has been difficult, presumably because of the complex inheritance of the trait. Grain mould results from infection by one or more parasitic fungal species, most commonly Fusarium moniliforme [Gibberella fujikuroi] and Curvularia lunata [Cochliobolus lunatus]. The objective of this study was to determine the inheritance of grain mould resistance by generation means analysis. The F1, F2, and backcross generations of a cross between 'Sureno' (a dual-purpose food grain and forage variety, resistant to grain mould) and 'RTx430' (a widely adapted inbred line, highly susceptible to grain mould) were evaluated in eight different field environments in Texas, USA. Significant differences in grain mould incidence between the generations evaluated in 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 mould 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 mould resistance. The results of this study indicate that selection in specific environments is useful for enhancing resistance to mould in these environments, but it may not be as effective in providing grain mould resistance across a wide range of environments |
Plný text