Effect of Glaucousness on Carbon Isotope Discrimination and Grain Yield in Durum Wheat

The effect of glaucousness on yield and transpiration efficiency was studied in durum wheat under Mediterranean conditions. Two groups of 16 genotypes, with contrasting glaucousness, were compared over 2 years for flag leaf and kernel carbon isotope discrimination, residual transpiration, specific leaf dry weight, biomass and grain yield. Significantly higher carbon isotope discrimination and lower specific leaf dry weight were noted in the glaucous lines. No significant effect of glaucousness was found on residual transpiration. Glaucous genotypes also exhibited higher grain yield, which was strongly correlated to the carbon isotope discrimination values. Results suggest that glaucousness has a negative effect on transpiration efficiency, which could be related to modifications of leaf energy balance. Higher stomatal conductance, reflected by the high carbon isotope discrimination, could mainly explain the higher grain yield found in the glaucous lines.