Studies on genotypic variability and inheritance of waterlogging tolerance in wheat

A study was undertaken to assess the combining ability effects, variance components, heterotic responses, heritability and correlations of waterlogging tolerance in a diallel cross involving five diverse bread wheat genotypes with contrasting tolerance response to waterlogging stress. The results showed that genotypic variability accounted for most of the variation among genotypes studied. Highly significant general combining ability (GCA) and specific combining ability (SCA) were observed for most of the characteristics studied, indicating that both additive and dominance gene effects were important in the inheritance of the waterlogging tolerance. GCA effects, however, were relatively more prevalent than SCA effects on most of the characteristics studied. The tolerant genotypes PRL/Sara and Ducula were the best combiners for waterlogging stress tolerance and for most other agronomic characteristics studied. Relatively high estimates of heritability and predictability ratios were also observed for most characteristics relevant to waterlogging tolerance, confirming the importance of both additive and non-additive gene effects in controlling the waterlogging tolerance in wheat genotypes studied. The degree of dominance for waterlogging tolerance characteristics was estimated to be in the partial and complete dominance range. Under waterlogging conditions, grain yield correlated with genotypically and phenotypically positively with all its components, biomass yields, plant height, days to heading, number of green leaves on the main stem and stress tolerance index, and negatively with percentage leaf chlorosis, area under leaf chlorosis progress curve and stress susceptibility index. Substantial mid- and high parent heterotic responses were observed for most characteristics in some crosses.