Antioxidative parameters in the seedlings of pigeonpea (Cajanus cajan (L.) Millspaugh) in response to Zn and Ni stresses.

The zinc (Zn) and nickel (Ni) as oxidative stress factors and associated responses of 6-day-old seedlings of two pigeonpea (Cajanus cajan (L.) Millspaugh) cultivars namely LRG30 and ICPL87 were studied. Zinc and Ni exposure increased lipid peroxidation in relation to their concentration. Reduction in dry matter accumulation of roots and shoots was noticed in Zn and Ni treatments. The activities of antioxidative enzymes such as superoxide dismutase, peroxidase and glutathione reductase registered higher values and the activity of catalase and the antioxidative substances such as ascorbic acid and total glutathione contents registered lower values in all the Zn and Ni treatments when compared to their controls. The levels of catalase, peroxidase and glutathione reductase and ascorbic acid and total glutathione contents were high in cv. LRG30 than in cv. ICPL87 in response to Zn and Ni treatments. However, the activity of superoxide dismutase, the major scavenger of O(2)(&z.rad;-) radical registered higher values in cv. ICPL87. The cv. LRG30 is less sensitive to Zn and Ni treatments compared to the cv. ICPL87. Correlation coefficients between the different antioxidant parameters and metal dose level, or dry matter accumulation, were established, assessing for an induced-oxidative stress. Additional evidence was provided by comparing the sensitivity of the two cultivars.