Abstract
In recent times, increasing interest has been directed toward the application of phytohormones such as indole-3-acetic acid (IAA), gibberellic acid (GA), and strigolactones (SLs) due to their potential in alleviating abiotic stress in various plant systems. These hormones are known to support critical physiological processes, particularly by enhancing the functioning of the ascorbate-glutathione (AsA-GSH) cycle, which is pivotal in maintaining redox balance. They contribute to improved plant development, photosynthetic performance, biomass accumulation, antioxidant defense activation, and reduction of oxidative damage. The present study evaluates the protective effects of exogenously applied IAA (100 µM), GA (100 µM), and SLs (5 µM) on wheat (Triticum aestivum L.) grown in soil amended with lead (Pb) and arsenic (As) at concentrations of 0, 100, and 200 mg kg⁻(1). Findings indicated that exposure to Pb and As substantially hindered growth parameters, photosynthetic attributes, the AsA-GSH redox cycle, subcellular distribution, and proline metabolism. Simultaneously, oxidative stress indicators and the transcriptional as well as biochemical levels of both enzymatic and non-enzymatic antioxidants were significantly elevated under heavy metal stress. However, the exogenous application of IAA, GA, and SLs mitigated these adverse effects by promoting plant growth and photosynthetic efficiency, upregulating antioxidant enzyme activities and related gene expressions, and lowering oxidative stress and heavy metal uptake. Additionally, these treatments optimized cellular compartmentalization, moderated proline levels, and strengthened the AsA-GSH cycle. Collectively, these outcomes underline the potential of hormone-based interventions as viable approaches for improving crop performance under heavy metal stress and contribute to the development of eco-friendly strategies for sustainable agriculture.