HARNESSING THE EFFECTS OF CADMIUM STRESS AND AMELIORATION BY NITRIC OXIDE AND HYDROGEN SULFIDE ON MINERAL NUTRIENT BALANCEAND ITS UPTAKE ALONG WITH NITROGEN METABOLISM IN SOLANUM LYCOPERSICUM L.

Cadmium (Cd) contamination in soil and water severely affects plant growth by disrupting nutrient homeostasis. This study investigates the potential ameliorative role of nitric oxide (NO) and hydrogen sulphide (HS) on mineral nutrient uptake, its balance and key nitrogen metabolism enzymes in Solanum lycopersicum L. The results indicated that the exposure to low Cd concentration (5ppm) led to an increase in dry biomass accumulation, suggesting a possible hermetic effect. However,higher Cd levels (25 ppmand 50 ppm) decreased the dry weight indicating Cd induced toxicity. Moreover, the plants subjected to Cd stress exhibited reduced uptake of essential nutrients, particularly potassium (K), calcium (Ca), magnesium (Mg) and iron (Fe). At the same time, they accumulateexcessive sodium (Na) and chloride (Cl).The activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) were significantly inhibited under Cd toxicity, leading to impaired nitrogen assimilation. The exogenous application of NO and H2S mitigated Cd induced damage by enhancing nutrient uptake, restoring ion balance, and improving nitrogen metabolism enzyme activity. The combined NO + H2S treatment was the most effective, suggesting a synergistic role in Cd stress tolerance. These findings highlight the potential of NO and H2S as protective agents in managing heavy metal stress in plants.