Carbon isotope discrimination and its relationship with water use efficiency in bread and durum wheat under water stress

Water use efficiency (WUE) is considered as a potential physiological trait that can be exploited in crop improvement programmes. However, progress in this direction is hindered due to non-avallabllity of a reliable screening method. Carbon isotope dlscriminatlon-(Δ) has been associated with differences in WUE of genotypes. However, despite numerous reports, the relationship between Δ¹³C and water use efficiency, as such under varied environments, is unclear. The present study investigates the relationship between WUE and Δ¹³C and interactions there on in order to enhance the potential application of CID In selection and breeding for higher WUE. Results reveal a positive correlation between CID and WUE. Bread wheat types showed higher discrimination under normal conditions than the durum wheat type. While under water stress the discrimination decreased for water stress tolerant types. The low CID values were recorded for C-306 whose tolerance to water stress Is known. Durum genotype, PDW-233. Showed low ¹³C discrimination and produced more mass under normal and stressful conditions. Across genotypes and treatments, a positive correlation between CID and WUE (r = 0.598*) was evident.