Boosting Salt Tolerance in Camelina cultivars through synergistic Impact of Exogenous Silicon and Selenium by modulating physiological attributes and Antioxidant activities

Abstract

Salt stress (SS) has emerged as one of the most pressing environmental threats to the production sustainability of oil-seed crops like camelina which necessitates finding out pro-environment and biologically feasible amelioration approaches. A study was performed to investigate the effects of exogenously applied silicon (Si) and selenium (Se) on two camelina varieties (Australian and Canadian) under SS conditions. The trial was comprised of two doses of Si and Se (5 and 10 ppm each) along with two co-application treatments entailing Si (5pp) + Se (5ppm) and Si (10 pp) + Se (10 ppm), whereas control treatments were kept for comparison purpose. The response variables included root-shoot length, fresh and dry weights, as well as leaf photosynthetic pigment content (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids), leaf gas exchange attributes, biochemical characters (total proline, total soluble sugar, total soluble protein, and total free amino acid) and antioxidant activities (APX, POD, CAT, and SOD). Results showed that SS significantly reduced all growth attributes of camelina, whereas the Australian camelina variety demonstrated greater salinity tolerance in comparison to the Canadian variety. The co-application of Si (10 pp) + Se (10 ppm) outperformed the rest of the treatments by recording the highest leaf chlorophyll a (1.69 mg/g FW), chlorophyll b (1.02 mg/g FW), carotenoids (2.89 mg/g FW), photosynthetic rate (17.02 µmole CO₂ m^− 2 s^− 1), transpiration rate (3.65 µmole CO₂ m^− 2 s^− 1), stomatal conductance (0.38 µmole CO₂ m^− 2 s^− 1), total proline (199.38 µmole/g DW), total soluble sugar (120.95 µmole/g FW), total soluble protein (12.02 mg/g DW) and total free amino acid (37.15 mg/g DW) in Australian camelina as compared to Canadian camelina. The same treatment also remained effective in triggering the activity of APX (3.89 Unit/min/g FW), CAT (165.19 Unit/min/g FW), POD (178.95 Unit/min/g FW), and SOD (237.63 Unit/min/g FW). Thus, the combined exogenous application of Si and Se holds bright perspectives in alleviating the deleterious impact of SS especially for the Australian variety, and could be recommended to camelina growers after thorough field investigations.