Effect of cadmium and chromium on fast growing pulp wood Tree species

Abstract

The present study investigated the effects of Cadmium (Cd) and Chromium (Cr III & Cr VI) on dry matter production, enzyme activity and metal extraction potential of three fast growing pulp wood species viz., She Oak (Casuarina junghuhniana Miq.), The Forest Red Gum (Eucalyptus tereticornis Sm.) and The White Lead tree (Leucaena leucocephala Lam. de Wit). Metal elements were applied in the form of Cd(Cl2)2 and K2CrO4 and Cr(NO3)3.9H2O at variegated concentrations viz., T1 (Control), T2 (lower level- 25 mg L -1 Cd, 10 mg L -1 Cr (VI) and 25 mg L-1 Cr (III)), T3 (Critical level - 50 mg L-1 Cd, 20 mg L-1 Cr (VI) and 50 mg L-1 Cr (III)) and T4 (higher level - 100 mg L -1 Cd, 40 mg L -1 Cr (VI) and 50 mg L -1 Cr (III)) under controlled conditions of light and temperature for 3 weeks. The biometrical parameters like, shoot length, root length, shoot dry weight, root dry weight and total dry matter production were recorded at 21 Days After Sowing (DAS). Similarly, activities of plant enzymes (catalase and peroxidase) and uptake of trace metals (Cd, Cr (VI) and Cr (III)) by the above said three species were also analyzed at 21 DAS. Decline in total dry matter production and enzyme activities were founded in all the three species after 25 mg L-1 and 10 mg L-1 and 25 mg L-1 for Cd, Cr (VI) and Cr (III) application respectively. Leucaena leucocephala was most affected followed by Eucalyptus tereticornis. But, Casuarina junghuhniana showed tolerance towards trace metal toxicity. Regarding uptake of trace metal, Eucalyptus tereticornis accumulated more Cd, Cr (VI) and Cr (III) compared to other species. In this study, Cr (VI) appeared to be more toxic to pulp wood tree species as compared to Cr (III) and Cd at germination stage (21 DAS) and Cd got accumulated more in plants than Cr (III) and Cr (VI).