Genetic component analysis of waterlogging tolerance in cucumber

Water-logging is one of the most important environmental stresses that severely limits crop growth and productivity. The objectives of this study was to estimate the genetic variation of F₃ families for waterlogging tolerance of cucumber by (i) estimating the variance component, broad and narrow-sense heritabilities of waterlogging traits and (ii) to determine the phenotypic and genetic correlations between these traits in the F₃ families in a greenhouse experiment. A set of 144 F₃ families derived from a cross between a PW0801 (susceptible) and PW0832 (tolerant) cucumber breeding lines were assessed for three waterlogging traits, tolerance (TOL), adventitious root formation (ARF) and shoot dry weight (SDW). The results showed that F₁ generation in the waterlogged treatment had substantial increase in mean value across all traits with values higher than mean of the two parents. The phenotypic and genetic correlations among waterlogged traits were significantly positive between TOL and ARF, TOL and SDW, and ARF and SDW. The magnitude of the variance component estimates for variations among F₃ family mean (σ²F₃) were generally higher than that of the mean variation of the F₃ families (σ²_mF3). The estimates of the additive genetic variance (σ²_A) for all treatments were high and positive in magnitude while their dominance variance (σ²_D) estimates were negative and smaller. Finally, with the wide range of genetic variability among F₃ family means coupled with the high narrowsense heritabilities suggest that cucumber cultivars with high level of waterlogging tolerance could be developed through breeding programme with the parental lines selected in the present study.