Synergistic effects of gibberellic acid, biochar, and rhizobacteria on wheat growth under heavy metal and drought stress

Abstract Wheat (Triticum aestivum L.), a vital crop constituting approximately 20% of global caloric intake, faces significant threats from heavy metal contamination, particularly cadmium (Cd) and chromium (Cr), along with drought stress, jeopardizing global food security. This study aimed to investigate the combined effects of these stressors and the potential of plant growth enhancers such as gibberellic acid (GA3), biochar (BC), and rhizobacteria to improve wheat growth. Conducted in a controlled greenhouse environment at The Islamia University of Bahawalpur, the experiment utilized a completely randomized design with three replications across 72 pots, each filled with clay loam soil. The experimental layout included 24 treatment combinations involving cadmium stress (6 mg/kg), chromium stress (300 and 600 mg/kg), drought stress simulated at -0.8 MPa soil water potential, and various applications of GA3 (200 mg L− 1) and biochar (0.6% and 0.9% w/w). Seedlings of T. aestivum cv. Dilkash-21, treated with Agrobacterium fabrum, showed significant growth metrics, with root lengths of 9.36 cm under 6 mg/kg Cd stress compared to 5.53 cm in controls. The treatment also increased shoot and root fresh weights by 24.7% and 22.5%, respectively, while chlorophyll content peaked at 2.26 mg/g under 6 mg/kg Cd. Additionally, electrolyte leakage decreased to 10.5%, and the vigor index improved to 1586.05 under Cd stress. These findings indicate that utilizing GA3 and biochar can mitigate the adverse effects of environmental stressors on wheat. Future research should focus on the underlying mechanisms of these treatments and explore their application in field conditions to further enhance wheat productivity and resilience against environmental stress.