Comparative effect of salinity on growth, grain yield, water use efficiency, δ13C and δ15N of landraces and improved durum wheat varieties

Abstract

Supplemental irrigation with low-quality water will be paramount in Mediterranean agriculture in the future, where durum wheat is a major crop. Breeding for salinity tolerance may contribute towards improving resilience to irrigation with brackish water. However, identification of appropriate phenotyping traits remains a bottleneck in breeding. A set of 25 genotypes, including 19 landraces and 6 improved varieties most cultivated in Tunisia, were grown in the field and irrigated with brackish water (6, 13 and 18dSm−1). Improved genotypes exhibited higher grain yield (GY) and water use efficiency at the crop level (WUEyield or ‘water productivity’), shorter days to flowering (DTF), lower N concentration (N) and carbon isotope composition (δ13C) in mature kernels and lower nitrogen isotope composition (δ15N) in the flag leaf compared with landraces. GY was negatively correlated with DTF and the δ13C and N of mature kernels and was positively correlated with the δ15N of the flag leaf. Moreover, δ13C of mature kernels was negatively correlated with WUEyield. The results highlight the importance of shorter phenology together with photosynthetic resilience to salt-induced water stress (lower δ13C) and nitrogen metabolism (higher N and δ15N) for assessing genotypic performance to salinity.