Salicylic acid alleviates salinity-caused damage to foliar functions, plant growth and antioxidant system in Ethiopian mustard (Brassica carinata A. Br.)

Abstract

Background: Soil salinity is considered as one of the major environmental factors that has reduced plant productivity worldwide. This study investigates the impact of salinity on plant growth attributes, biochemical and physiological leaf characteristics in two cultivars (Adet and Merawi) of Brassica carinata and also explores the role of salicylic acid (SA) in mitigating the effect of salt stress. Methods: Four-week-old cultivars were treated with NaCl (50, 100 and 150 mM) and SA (0.5 mM) and watered regularly with 100% field capacity. Thus, they were grown under eight different treatments (T1 = no NaCl, no SA; T2 = 0 mM NaCl with 0.5 mM SA; T3 = 50 mM NaCl without SA; T4 = 50 mM NaCl with 0.5 mM SA; T5 = 100 mM NaCl without SA; T6 = 100 mM NaCl with 0.5 mM SA; T7 = 150 mM NaCl without SA; and T8 = 150 mM NaCl with 0.5 mM SA). Nine-week-old cultivars were sampled for analyzing the growth attributes, plant water status, nitrate reductase activity, proline accumulation, photosynthetic traits, lipid peroxidation level and activity of antioxidant enzymes. Results: Salinity treatments hampered the overall plant growth performance in a dose-dependent manner. Salinity also reduced photosynthetic efficiency by inhibiting chlorophyll synthesis, nitrate reductase activity, chlorophyll fluorescence, stomatal conductance, net photosynthetic and transpiration rates and plant water status. On the other hand, SA application alleviated the adverse effects of salinity and improved the performance of the studied parameters in both the cultivars. Higher dose of salinity increased proline production, but SA application mitigates this impact in both the cultivars studied. The activity of antioxidant enzymes increased under salt stress in a dose-dependent manner. SA treatment to normal or salinity-stressed plants increased the enzymes activity, showing that SA has a crucial role in modulating the cell redox balance and protecting the plants from oxidative damage. SA significantly reduced the salinity-caused effects on the overall performance of plants and their antioxidant systems in both the cultivars. Of the two cultivars, Adet was more tolerant to salinity than Merawi. Conclusions: Foliar application of SA improved the performance of Ethiopian mustard cultivars and mitigated the damage caused by salt stress.