ASSESSMENT OF CADMIUM AND COBALT INDUCED RESPONSES IN THELYPTERIS DENTATA (FORSSK.) E.P. ST. JOHN: A POTENTIAL HEAVY METAL ACCUMULATOR

This hydroponic study investigated the effects of cadmium (Cd) and cobalt (Co) toxicity on Thelypteris dentata (Synonym.Christella dentata Forssk., Family Thelypteridaceae), a fern species with potential heavy metal accumulation capabilities.Morphological, biochemical, and antioxidative enzyme responses were evaluated at varying concentrations (0, 100, 600, and 1200 ppm) over 5 and 15 days time interval and changes were monitored after 5 and 15 days of exposure time.The concentrations ranging from 100-1200 ppm were chosen considering their environmental relevance and their toxicity thresholds from previous research studies.Short-term exposure (5 days) revealed increased antioxidative enzyme activities (APX, POD, SOD) in Cd and Co-treated plants, except for APX at 1200 ppm concentration of Cd.However, prolonged exposure (15 days) caused significant declines in growth rate, biomass, and relative water content, accompanied by interveinal chlorosis, wilting, and necrosis in Cd-treated plants, leading to the complete death of plants.Cd and Co accumulation increased with increase in concentration in both fronds and roots.The study indicates that T. dentata cannot tolerate Cd concentrations 100 ppm and Co concentrations >600 ppm.Bioconcentration and translocation factors <1 suggest an exclusion mechanism, with high Cd and Co accumulation in roots.Therefore, it can be concluded that Thelypteris dentata exhibits greater tolerance to Co than Cd under long-term heavy metal stress which makes it a potential indicator of Co-contaminated soil.