Salinity stress mitigation in wheat through synergistic application of ascorbic acid, nanoparticles and Salvadora oleoides extract

Salinity stress adversely affects wheat growth and productivity, necessitating effective mitigation strategies. This study investigates the combined impact of ascorbic acid (AsA), silver nanoparticles (NPs), and Salvadora oleoides aqueous leaf extract (LE) on wheat tolerance to salinity stress. A randomized complete design (RCD) was employed with fourteen treatments: T1 (5 mM AsA), T2 (10 mM AsA), T3 (20 ppm AgNPs), T4 (40 ppm AgNPs), T5 (5% S. oleoides LE), T6 (10% S. oleoides LE), T7 (20 ppm AgNPs + 5 mM AsA), T8 (20 ppm AgNPs + 10 mM AsA), T9 (40 ppm AgNPs + 5 mM AsA), T10 (40 ppm AgNPs + 10 mM AsA), T11 (20 ppm AgNPs + 5% S. oleoides LE), T12 (20 ppm AgNPs + 10% S. oleoides LE), T13 (40 ppm AgNPs + 5% S. oleoides LE), and T14 (40 ppm AgNPs + 10% S. oleoides LE). Wheat plants were subjected to salinity stress (SS) and no-stress conditions (NoSS) for 50 days. Chlorophyll content, DPPH activity, total soluble proteins and sugars, antioxidant enzyme activities, lipid peroxidation, leaf ion concentrations, and nutrient uptake were analyzed. Under SS, T6 (10% LE) showed the lowest chlorophyll-a (90.04%) and b (57.84%). DPPH activity was highest in NoSS with T9 (40 ppm NPs + 5 mM AsA) at 14.40%, and lowest in SS with T6 (10% LE) at 6.67%. Total soluble proteins and sugars were highest in NoSS with T9 (40 ppm NPs + 5 mM AsA) and T6 (10% LE). In SS, SOD activity peaked with T6 (10% LE) at 8.39 U/mg protein, while CAT activity was highest with T9 (40 ppm NPs + 5 mM AsA) at 6.25 U/mg protein. Lipid peroxidation was highest in SS with T6 (10% LE) at 14.67 µM MDA/g fresh weight. Leaf Na and Cl concentrations were highest in SS with T9 (40 ppm NPs + 5 mM AsA), at 14.26% and 44.15%, respectively. The combined application of 40 NPs and 5 AsA (T9) proved most effective in enhancing chlorophyll content and DPPH activity under NoSS, while 10% LE (T6) showed significant improvements in SOD activity and lipid peroxidation mitigation under SS. Future research should explore optimizing treatment concentrations and combinations to further enhance wheat stress tolerance and evaluate long-term effects on crop yield and quality.