WHEAT AND NICKEL: UNDERSTANDING PLANT RESPONSES FOR IMPROVED TOLERANCE STRATEGIES

Nickel (Ni) contaminated soil is a persistent risk lowering agricultural crop productivity and posing significant health risks to humans worldwide. Therefore, a 30-days laboratory experiment was conducted to investigate the physiological and enzymatic responses of five varieties of wheat plants to different Ni treatments (0, 200 and 400 mM). Germination, growth, photosynthetic activities, and antioxidant responses were measured to assess the impact of Ni effect on these parameters. The results showed that germination rates reached 100% under control conditions, but they significantly declined to 47% at 400 mM of Ni. The varieties Lalma and Paseena exhibited sensitivity, while Wadan and PS-13 demonstrated tolerance to stress promoted by Ni. With in-creasing Ni concentrations, fresh shoot weight and shoot length were reduced, with Lalma and Paseena being the most affected. In contrast, Wadan and PS-13 showed higher tolerance to Ni. Also, stress caused by Ni decreased chlorophyll and carotenoid con-tent in all wheat varieties (Lalma, Paseena, and Zincol), except for Wadan and PS-13, which displayed greater tolerance. Antiox-idant enzyme activities, including peroxidase, ascorbate peroxidase, and catalase, increased in Lalma, Paseena, and Zincol under Ni stress. PS-13 exhibited the highest antioxidant enzyme activity. Leaf gas exchange parameters declined with increasing Ni levels, with PS-13 showing greater tolerance. Proline production significantly increased in Lalma and Paseena under stress caused by Ni. Principal component analysis (PCA) and heat maps revealed distinct trait variations. PS-13 displayed high toler-ance, while Lalma and Paseena were more susceptible. In conclusion, this study demonstrates the diverse responses of wheat vari-eties to Ni-induced stress, providing crucial insights into physiological and biochemical changes. These findings are pivotal for developing strategies to enhance nickel stress tolerance in wheat cultivation, ultimately mitigating the adverse consequences on crop productivity, particularly in Ni-contaminated environments.