Salinity Induces Accumulation of Soluble Sugars and Alters the Activity of Sugar Metabolising Enzymes in Rice Plants

Changes in the starch and sucrose contents, and the sucrose phosphate synthase, acid invertase, and starch phosphorylase activities were studied in the seedlings of salt sensitive and salt tolerant rice cultivars growing under two NaCl concentrations (7 and 14 dS m-1) for 20 d. Under salinity, the starch content in roots declined more in salt sensitive cvs. Ratna and Jaya than in salt tolerant cvs. CSR-1 and CSR-3 and was unchanged in shoots. The contents of reducing and non-reducing sugars, and the activity of sucrose phosphate synthase was increased more in the sensitive than in the tolerant cultivars. Acid invertase activity decreased in shoots of the salt tolerant cultivars, whereas increased in salt sensitive cultivars. Starch phosphorylase activity decreased in all cultivars.