Effect of cadmium on growth, mineral composition and enzyme activity of Sugarcane

An attempt has been made to study the effect of differential levels of Cd (0, 5, 10, 100, 200 ppm Cd as cadmium chloride) on growth, cell division, chlorophyll content, and activity of catalase and peroxidase enzymes, foliar anatomical characters and essential nutrient contents in sugarcane (Sachharum sp. hybrids CoLk 8102 and CoJ 64) planted under soil pot culture conditions. Very low levels of Cd (5 and 10 ppm) decreased most of the growth attributes studied, viz. leaf number, leaf area, plant height, leaf width, fresh and dry weight of different plant parts, reduction being more with an increase in Cd supply. In variety CoLk 8102, the depression was 45, 51 and 71% in leaf number, plant height and leaf area respectively whereas CoJ 64 exhibited 18, 11 and 15% depression at 200 ppm Cd supply. Cytological studies indicated steady decline in mitotic index with increasing Cd dose in both the varieties. Chlorophyll a and b and soluble protein contents decreased with an increase in Cd supply in both the varieties. Peroxidase activity was found high while catalase activity was low in Cd supplied plants. Foliar anatomical studies indicated marked reduction in number of minor veins of LTM leaves but the major veins were not affected due to Cd addition in growth medium. Essential nutrients, viz. P, Fe, Mn, Cu and Zn determined in different plant parts revealed lower content of P, Fe, Mn Cu and Zn in leaves and higher content of Fe and P in root tissue at higher Cd levels (100 and 200 ppm Cd). Results obtained indicated that high dosages of Cd (100 and 200 ppm Cd) exerted significant inhibitory effect on shoot and root growth, cell division coupled with changes in mineral composition, activity of catalase and peroxidase enzymes which in turn resulted in reduction in biomass yield of sugarcane. Both the varieties were affected due to excess Cd, effect being less pronounced in variety CoJ 64 in terms of lower decrease in growth attributes.