Stability of Carbon Isotope Discrimination and Grain Yield in Durum Wheat

Abstract

Carbon isotope discrimination (Δ) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in bread wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), with potential value for durum wheat (Triticum turgidum convar. durum Desf. MacKey). We evaluated the genetic variation for Δ, the relationship between Δ and grain yield, and the magnitude of genotype × year (G × Y) interactions in durum wheat. Field experiments were conducted under Mediterranean conditions on 144 durum wheat accessions during three successive years. Grain yield and carbon isotope discrimination of flag leaves (ΔF) and kernels (ΔK) were measured. Large genotypic and year variation was observed for ΔF and ΔK. Flag leaf Δ was correlated with grain yield in 2 yr characterized as having greater water limitation (r = 0.29 − 0.38, P < 0.001). Conversely, ΔK and grain yield were significantly correlated in all 3 yr (r = 0.49 − 0.52, P < 0.001). In addition, G × Y interactions were significant for ΔF, ΔK and grain yield. However, significant correlations (P < 0.001) were noted for ΔK across years. As a result, ΔK may serve as a better predictive criterion for higher grain yield under Mediterranean conditions.