Assessment of the physio-biochemical performance of Tunisian barley landraces under deficit saline-irrigation during grain filling stage

Salinity is one of the main and important abiotic stresses that adversely affects crop growth, development and production. In this study, two barley (Hordeum vulgare L.) landraces were subjected to three treatments of deficit saline-irrigation (12 dS/cm) (T0 = 100%ETc, T1 = 75%ETc, and T2 = 50%ETc) during grain filling stage. Carbon isotope discrimination (Δ13C) was associated with some physio-biochemical parameters to evaluate barley response to saline conditions. Results of this study showed that deficit saline-irrigation significantly (p < 0.05) decreases Δ13C in both barley landraces. Moreover, photosynthetic rate (A), transpiration (E), stomatal conductance (gs), and instantaneous water use efficiency (iWUE) were significantly affected by treatments. Relative water content (RWC), chlorophyll a, and chlorophyll (SPAD) value were significantly (p < 0.01 and p < 0.001) were affected by deficit saline-irrigation. In addition, phenolic compounds were affected by treatments and landraces (except syringic and p-coumaric acids), and their interactions (except syringic acid). Moreover, high correlations were noticed between Δ13C and physio-biochemical parameters. Results suggested that both barley landraces make a higher iWUE, and a weak variation in phenolic compounds. Moreover, Δ13C associated with physio-biochemical traits can also be good criteria for screening of salt-tolerance of barley during grain filling stage. Taken together, our study suggests that the response to deficit saline-irrigation in barley landraces involves an interplay between various physiological and biochemical mechanisms mainly related to Δ13C.