Relationship of Carbon Isotope Discrimination to Water Use Efficiency and Productivity of Barley Under Field and Greenhouse Conditions

This study was conducted to evaluate the application of carbon isotope discrimination (CID) as a selection criterion for improving water use efficiency (WUE) and productivity of barley (Hordeum vulgare L.) under field and drought‐stress conditions in a greenhouse. A total of 54 genotypes were screened for variability in CID under field conditions, while 23 genotypes were evaluated under water‐deficit conditions in the greenhouse. A survey of leaf CID of 54 genotypes at two field locations showed more than 2.14‰ difference between extreme genotypes. Significant (P ≤ 0.05) genotypic variation was found in WUE and CID that had a negative strong correlation. There was a negative correlation between leaf CID and aerial biomass in the greenhouse and among six‐row genotypes in the field. Correlations between leaf CID across field locations and across irrigation regimes in the greenhouse were significant (experiment 1, r = 0.79 and 0.94 for six‐ and two‐row genotypes), suggesting stability of the CID trait across different environments. Overall, these results indicate the potential of leaf CID as a reliable method for selecting for high WUE and productivity in barley breeding programmes in the Canadian prairies. Further work is currently underway to determine heritability/genetics of leaf CID and application of molecular marker‐assisted selection for the traits in barley breeding programmes.