Sheokand, SunitaAnita Kumari2017-09-062017-09-062004http://krishikosh.egranth.ac.in/handle/1/5810030541The present investigations were conducted on pea genotype hisar harit to study the accumulation of cd in different plant parts and to evaluate the causes of cd toxicity in relation to antioxidant defence mechanism and its possible amelioration by ascorbic acid and putrescine. in the first experiment plants were grown in dune sand treated with 0, 100, 200 and 400 m cdcl2. Cd caused significant but variable decline in dry weight of all the plant parts, though it accumulated mainly in the roots. in the second experiment the effect of cd on reactive oxygen species (ros) scavenging enzymes was studied. The plants were treated woth 0, 100, 400 and 800 m cdcl2 at the vegetative stage and sampled after 3 and 9 day. Cd induced a significant increase in lipid peroxidation in the leaves and nodules, but had no appreciable effect on total soluble protein and non-protein thiols. A concentration dependent increase in ros production was observed, which could be compensated to some extent by increased activity of sod, apx and cat isoforms in leaves. higher concentrations of cd resulted in a decrease in sod and apx activity could be compensated to some extent by increased catalase activity in the nodules. in the third experiment the effect of ascorbic acid and putrescine on cd induced toxicity in leaves and nodules was studied. Ascorbic acid was more effective in ameliorating the deleterious effects of cd on plant growth, lipid peroxidation and ros production. Among the antioxidant enzymes, asa had a positive effect on apx isozymes in cd treated plants. Among the two putrescine concentration used, the lower concentration of 0.5 mm. Was more effective in ameliorating the toxic effects of cd. Putrescine had a positive effect on catalase and sod isozymes. Key words: Pisum sativum L. , cadmium, antioxidative enzymes, reactive oxygen species(ROS).enEffect of Cd toxicity and its possible alleviation by putrescine/spermidine and ascorbic acid in Pisum sativum L.Thesis