Enhancing Wheat Tolerance to Cadmium Stress through Moringa Leaf Extract Foliar Application

Cadmium, a hazardous heavy metal prevalent in plants and soil, poses a significant threat to human health, particularly as approximately 60% of the global population consumes wheat, which can accumulate high levels of Cd through its roots. This uptake leads to the translocation of Cd to the shoots and grains, exacerbating the potential health risks. However, promising results have been observed with the use of moringa leaf extract (MLE) foliar spray in mitigating the adverse effects of Cd stress. The current experiment was conducted to find out the Cd stress tolerance of wheat varieties V1 = Akbar-19 and V2 = Dilkash-2020 under exogenous spray of MLE. The treatments of this study were T0 = 0% MLE + 0 µM Cd, T1 = 3% MLE + 0 µM Cd, T2 = 0% MLE + 400 µM Cd, and T3 = 3% MLE + 400 µM Cd. Cd stress demonstrated a significant reduction in morphological attributes as shoot and root fresh weight (22%), shoot and root dry weight (24.5%), shoot and root length (22.5%), area of leaf and number of leaves 30.5%, and photosynthetic attributes (69.8%) in comparison with control. Exposure of wheat plants to Cd toxicity cause oxidative stress, increased H₂O₂, and MDA up to 75% while foliar application of MLE reduced the activities of reactive oxygen species (ROS). The activity of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbic acid (AsA) increased up to 81.5% as well as organic osmolytes such as phenolics, total soluble proteins, and total soluble sugars were improved up to 77% by MLE applications under Cd stress. Higher accumulation of ionic contents root Na⁺ (22%) and Cd (44%) was documented in plants under Cd stress as compared to control, while uptake of root mineral ions Ca²⁺ and K⁺ was 35% more in MLE-treated plants. In crux, Cd toxicity significantly declined the growth, photosynthetic, and biochemical parameters while 3% MLE application was found effective in alleviating the Cd toxicity by improving growth and physiological parameters while declining reactive oxygen species and root Na⁺ as well as Cd uptake in wheat.