The Proper Supply of S Increases Amino Acid Synthesis and Antioxidant Enzyme Activity in Tanzania Guinea Grass Used for Cd Phytoextraction

Increased Cd concentrations in the environment impair plant growth, but plants properly supplied with S may develop greater tolerance to the damage caused by Cd and be used in the remediation of contaminated environments. The aim of this study was to evaluate the Cd-phytoextraction potential of Panicum maximum cv. Tanzania grown with S rates and to identify alterations in the concentrations of nutrients and amino acids and in the activity of some antioxidant enzymes under Cd stress conditions. Combinations of five S rates (0.1, 1.0, 1.9, 2.8, and 3.7 mmol L^?1) and five Cd rates (0.0, 0.5, 1.0, 1.5, and 2.0 mmol L^?1) in a nutrient solution were provided in two plant growth periods. Concentrations of N, P, and Zn increased, while K, Fe, and Mn decreased with exposure to Cd. The concentration of Ca decreased as the S supply was increased. Isoleucine, leucine, proline, and valine concentrations increased with exposure to Cd and with higher levels of S. The APX activity was higher at the highest Cd exposure level. Activity and number of SOD and GR isoforms in the roots and of CAT in the shoots of the regrown plant decreased at the highest level of contamination by Cd, which was lessened by the supply of greater S rates. Tanzania guinea grass grown with an adequate supply of S has the potential for phytoextraction of Cd-contaminated environments.