Enhanced Salt Stress Tolerance in Maize Using Biostimulant and Biosurfactant Applications

This research was conducted to investigate effects of biostimulants containing plant growth-promoting rhizobacteria and enriched biosurfactants, which were tested individually and in combination (biostimulant + enriched biosurfactant) on plant growth parameters, physiological and biochemical properties of maize seedlings under different salinity conditions (0, 100, 200 mM NaCl). In the experiment, biostimulant (B: 0.3 g/L), enriched biosurfactant (E-S: 3 mL/L), and their combination (B + E-S) were applied by foliar spray at each NaCl level. Salt stress negatively affected the growth and physiological traits of maize seedlings, while biostimulant and enriched biosurfactant improved these parameters. Under severe salinity stress (200 mM NaCl), the biostimulant, enriched biosurfactant, and their combined application markedly mitigated oxidative and osmotic damage. Compared with the untreated 200 mM NaCl group, these treatments (B, ES, B + ES) reduced proline accumulation by 65%, 52%, and 70%; hydrogen peroxide (H2O2) level by 53%, 39%, and 58%; and malondialdehyde (MDA) content by 72%, 50%, and 73%, respectively. These reductions indicate a substantial decrease in oxidative stress and membrane lipid peroxidation. In conclusion, biostimulant and enriched biosurfactant applications may be a promising approach to reduce the negative effects of salinity stress on maize.