Ash content might predict carbon isotope discrimination and grain yield in durum wheat

•  Dry mass per unit of leaf area (LDM) and ash content were evaluated as alternative criteria for carbon isotope discrimination (Δ) in durum wheat (Triticum durum) flag leaves and grains. •  Using correlation analysis the relationships between the three parameters (LDM, Δ, ash content) and productivity were determined over three consecutive years in 37 field-grown durum wheat genotypes under contrasting drought conditions. •  Highly significant differences were found between years and among genotypes for all measured traits. Grain Δ and ash content, and LDM and flag leaf Δ were negatively correlated under nondroughted conditions. Positive correlations were found between grain yield, harvest index and both Δ and ash content of the flag leaf under drought. No significant correlations were found between LDM and both Δ and grain yield. •  Differences in LDM do not predict variations in Δ, whereas ash content of grain and flag leaf (under droughted conditions) might be useful in predicting Δ and grain yield. Ash content might provide an alternative screening method in the improvement of drought tolerance and yield stability in durum wheat.