Effect of Cadmium on Soluble Sugars and Enzymes of their Metabolism in Rice

The effect of cadmium on the content of starch and sugars, and changes in the activities of the enzymes of sugar metabolism were studied in growing seedlings of rice (Oryza sativa L.) cultivars Ratna and Jaya. During a 5- to 20-d exposure at 100 M or 500 M Cd(NO₃)₂ in the growth medium an increase in the content of total soluble sugars and reducing sugars, and decrease in the content of non-reducing sugars was observed. Cd-induced increase in the sugar content was greater in shoots than in roots. No definite pattern of changes in starch content or in -amylase activity was observed. Presence of 100 or 500 M Cd(NO₃)₂ increased the activities of sucrose degrading enzymes, acid invertase and sucrose synthase, whereas the activity of sucrose phosphate synthase declined.