SYNTHESIS AND STORAGE OF SUCROSE IN RELATION TO ACTIVITIES OF ITS METABOLIZING ENZYMES IN SUGARCANE CULTIVARS DIFFERING IN MATURITY

Metabolic changes in the contents of sucrose and hexoses in relation t o the activities of invertase, sucrose synthase and sucrose-phosphate synthase in early (CoJ 64) and late (Co 1148) maturing cultivars of su garcane have been studied. During early stages of cane growth, lower a ctivities of sucrose synthase and sucrose-phosphate synthase in leaf b lade in CoJ 64 over Co 1148 were observed. However, sucrose Content in sheath/blade was higher in CoJ 64 than in Co 1148. With the advancing age, the activity of soluble acid invertase (pH 5.4) in stem declined more rapidly in CoJ 64. This resulted in building up of high ratio of sucrose/invert sugars in stem tissue of this cultivar. Feeding unifor mly-labelled sucrose and glucose to the cut discs of leaf sheath resul ted in higher uptake of C-14 in CoJ 64 than in Co 1148. Uptake by stem tissue discs of C-14 from sucrose was' less than that from hexoses. B ased on these results, it is suggested that (i) the rapid fall in the activity of soluble acid invertase in stem concomitant with fast accum ulation of sucrose in this tissue is an index of early maturity of the cane, and (ii) high content of sucrose in sheath is a reflection of a n efficient translocation of this sugar in early maturing cultivars.