Inheritance of evapotranspiration and transpiration efficiencies in diallel F1 hybrids of durum wheat (Triticum turgidum L. var. durum)

Inheritance of water use and transpiration efficiency was studied in diallel F1 hybrids from six cultivars of T. durum, selected for their different responses to drought stress. Plants were grown in 10 l pots at optimal (control) and low soil moisture levels in the glasshouse. GCA and SCA effects were significant at both soil moisture levels. Results demonstrated that evapotranspiration (ETE) and transpiration efficiency (TE) were under additive and dominant gene control. Interactions of GCA and SCA with moisture levels were also highly significant. GCA effects were the major components of the genetic variance of the biological and generative measures of ETE and TE. Narrow sense heritabilities for both ETE and TE based on grain yield were higher at the soil stress moisture level. Heritability estimates of ETE and TE based on the total biological yield, however, declined under the lower soil moisture level. Measures of ETE and TE showed significantly high and positive genotypic and phenotypic correlations among them as well as with grain yield and harvest index. In most cases, genotypic correlations were higher than phenotypic correlations. The results suggest that selection for high ETE and TE in terms of grain yield should be undertaken under both stress and optimal conditions. Selection in early segregating generations may lead to effective identification of desirable recombinants.