Foliar spray of salicylic acid and gamma-aminobutyric acid mitigates chromium toxicity in barley by regulating antioxidant defense, nutrient uptake, and secondary metabolites

Chromium (Cr) contamination severely hinders plant growth and biomass production. Salicylic acid (SA) and gamma-aminobutyric acid (GABA) play a vital role in improving plant stress resilience. So for, their synergistic effects in mitigating Cr toxicity remain unexplored. Thus, this research aimed to examine the effects of SA and GABA in mitigating the toxic effects of Cr in barley.

The study included Cr stress (0 and 40 mg kg^− 1), two barley cultivars (Sultan-17 and Haider-93), and foliar sprays of SA (1 mM) and GABA (1 mM).

Chromium toxicity significantly decreased growth and yield in both cultivars by increasing hydrogen peroxide (H₂O₂: 84%), Cr accumulation, and decreasing leaf water content (37–42%), chlorophyll synthesis (36–40%), and nutrient uptake. The foliar spray of SA + GABA markedly retrieved the toxic impacts of Cr by minimizing the Cr accumulation in roots (54–58%), leaves (46–50%), H₂O₂ (55–62%), increasing the chlorophyll synthesis, leaf water contents (52–59%), osmolytes synthesis, and antioxidants activities (9–91%), thereby improving the growth and yield. Additionally, SA + GABA improved the secondary metabolites production and maintained the ionic balance by increasing the nutrient uptake, thereby improving the barley growth and yield. Overall, cultivar Sultan-17 performed appreciably well compared to Haider-93 owing to its better potential to counteract Cr.

Thus, co-applied SA and GABA mitigate Cr toxicity by improving antioxidant defense, photosynthetic pigments, secondary metabolites production, and restricting the Cr uptake. These findings provides foundation to develop eco-friendly and economical measures to enhance crop productivity and contaminated soils.