Sucrose-Enzyme Relationships in Immature Sugarcane as Affected by Varying Levels of Nitrate and Potassium Supplied in Sand Culture

Abstract

Immature sugarcane plants grown in sand culture were subjected to conditions of potassium and nitrate stress in order that abnormal carbohydrate levels would be induced. The objective was to learn what areas of sugar metabolism were involved in the degradation of sucrose. The methods centered upon leaf enzymes, of which the following were identified and measured: Amylase, invertase, hexokinase, acid phosphatases, phosphorylase, phosphohexose isomerase, aldolase, triose phosphate dehydrogenase, phosphoglyceryl kinase, pyruvic carboxylase, condensing enzyme, α-ketoglutaric carboxylase, isocitric dehydrogenase, cytochrome-C reductase, fumarase, transaminase, oxalacetic carboxylase, peroxidase, catalase, and polyphenol oxidase. The enzyme preparations consisted of dialyzed water-soluble protein extracted from freeze-dried leaf tissue and precipitated with ammonium sulfate between 32- and 95-percent saturation. Sugar determinations for leaf and sheath tissue included total ketoses, sucrose, fructose, total reducing sugars, and glucose. Sheath-percent-moisture, total dry weight, and leaf protein were also measured. Treatments were applied from 9 weeks to 27 weeks of age and a total of seven harvests were made at 21-day intervals.