Abstract
The present study is based on the application of H(2)S as an exogenous antidote in Spinacia oleracea (spinach) plants grown in Cd-contaminated (50 ppm) soil. The different doses of H(2)S in the form of NaHS (10, 50, 100, 200, and 500 μM) have been applied as a foliar spray to regulate the physiological attributes under Cd toxicity. Over to control, the plants grown in Cd alone showed a reduction in the fresh biomass by 48% with more production of oxidative biomarkers (H(2)O(2), SOR, and MDA content) and antioxidative enzymes (SOD, POD, APX, and GR). Further, with the exogenous application of H(2)S, among all the doses the fresh biomass was found to be maximally increased at 100 μM dose by 76%, and the Cd content was reduced significantly by 25% in the shoot compared to plants grown in Cd treated soil alone. With the decrease in Cd content in the shoot, the production of H(2)O(2), SOR, and MDA content was reduced by 52%, 40%, and 38% respectively, at 100 μM compared to the plants grown in Cd-treated soil. The activities of estimated antioxidative enzymes showed a reduction in their activities up to 100 μM. Whereas, Glutathione reductase (GR) and Phytochelatins (PCs) showed different trends with their higher values in plants treated with NaHS in the presence of Cd. At 100 μM the GR and PCs, respectively showed 48% and 37% increment over Cd-treated plants alone. At this dose, the relative expression of SOD, POD, APX, GR, and PCS5 (Phytochelatin synthetase enzyme) genes, and other functional activities (SEM and fluorescence kinetics) supported the best performance of plants at 100 μM. Therefore, among all the doses, 100 μM dose of H(2)S has significantly reduced the Cd toxicity by maintaining the growth and other functional traits of plants. The correlation analysis also supported the result by showing a relationship between H(2)S application and Cd uptake. So, with this strategy, the plants grown in metal-contaminated fields can be improved qualitatively as well as quantitatively. With further experimentation, the mode of application could be explored to increase its efficiency and to promote this strategy at a wider scale. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-023-01389-3.