Ascorbic and citric acids mitigate cadmium stress and reduce metal accumulation in spinach grown in alkaline...

Cadmium (Cd) is a toxic heavy metal released through various industrial processes, mining, batteries disposal and agro-chemicals application posing serious risks to agricultural production and food safety. Limited research has investigated the potential of organic chelators, such as ascorbic acid (AsA) and citric acid (CA), to mitigate Cd toxicity and reduce its bioaccumulation in plants. Current pot study was conducted to evaluate the effects of Cd stress on two spinach varieties, i.e., Green Gold (Hybrid) and AARI Desi (Conventional), grown in sandy clay loam soil, and assessed the efficacy of foliar-applied AsA, CA, and their combination in alleviating Cd-induced stress. Stress was applied by irrigating the crop with Cd-contaminated water (1 mg L^-1) whereas organic acids, AsA and CA, were applied at 10 mM concentration as individual treatments and 5 mM + 5 mM as combined treatment. Cd stress significantly reduced root and shoot growth, physiological attributes, and biochemical parameters, while enhancing antioxidant enzyme activity and Cd accumulation in both varieties. Foliar applications of AsA, CA, and particularly combined application significantly improved plant growth and biomass, chlorophyll concentration, and biochemical traits, while markedly reducing Cd uptake in roots and leaves. The combined application of AsA and CA reduced the Cd concentration in shoots by 36% and in roots by 40% and increased shoot dry weight up to 43% and root dry weight up to 50% compared to cadmium stressed plants. Overall, the study demonstrates that AsA, either individually or in combination with CA, enhances the antioxidant defense and promotes metal chelation, thereby reducing oxidative damage and Cd bioaccumulation. This ultimately leads to improved growth and physiological performance of spinach under Cd stress.