Abstract
Cadmium (Cd) toxicity reduces growth and yield of crops grown in metal-polluted sites. Research was conducted to estimate the potential of hydrogen sulphide (H2S) to mitigate toxicity caused by Cd in fenugreek seedlings (Trigonella foenum-graecum L.). Different concentrations of CdCl2 (Cd1-1 mM, Cd2-1.5 mM, Cd3-2mM) and H2S (HS1-100 mu M, HS2-150 mu M, HS3-200 mu M) were assessed. Seeds of fenugreek were primed with sodium hydrosulphide (NaHS), as H2S donor. Seedlings growing in Cd-spiked media treated with H2S were harvested after 2 weeks. Cd stress affected growth of fenugreek seedlings. Cd toxicity decreased leaf relative water content (LRWC), intercellular CO2 concentration, net photosynthesis, stomatal conductance and transpiration. However, application of H2S significantly improved seedling morphological attributes by increasing the activity of antioxidant enzymes, i.e. APX, CAT and SOD, in Cd-contaminated soil. H2S treatment also regulated phenolic and flavonoid content. H2S-induced biosynthesis of spermidine (Spd) and putrescine (Put) could account for the enhancement of growth and physiological performance of fenugreek seedlings under Cd stress. H2S treatment also reduced H2O2 production (38%) and electrolyte leakage (EL, 51%) in seedlings grown in different concentrations of Cd. It is recommended to evaluate the efficacy of H2S in alleviating Cd toxicity in other crop plants.