Effects of Variable Calcium and Manganese on the Enzyme, Nucleotide, and Nutrient Constituents of Sugarcane Grown by Sand Culture

Abstract

Immature sugarcane was subjected to variable calcium (Ca) and manganese (Mn) in sand culture. Two levels of Ca were provided in factorial combination with three levels of Mn. Leaf samples were harvested for analysis after 3 months of treatment. There were three objectives: 1, To determine whether Ca could modify the rate of Mn uptake; 2, to determine main effects and interactions of Ca and Mn on specific enzymes; and 3, to study Ca and Mn effects on sugar and nucleotide content of leaves. The following results were obtained : 1. High Ca, 10 meq./liter, enhanced Mn uptake rather than cause Mn suppression. 2. Silicon content was decreased by high Mn (100 p.p.m.), but only when Ca was low. Ca thus is able to interfere with the Mn X Si interaction by which increasing Mn supply decreases Si uptake. 3. Leaf sucrose content was generally higher among plants receiving low Ca. This verifies observations by other workers. 4. High Mn appeared to substitute for high Ca in its influence upon sucrose content and amylase activity. A high-Ca effect upon amylase is induced by Mn without increasing Ca content. 5. High Mn greatly retarded amylase action when Ca supply was low, but had no effect when Ca supply was high. 6. Peroxidase action was relatively high among plants containing less sucrose, verifying earlier observations at this laboratory. High Ca greatly stimulated the enzyme. 7. Content of acid-soluble nucleotides did not vary greatly among treatments. Reducing sugar and total phosphorus content of nucleotide preparations varied strikingly. Sugar content was greatest in preparations from plants receiving both high Ca and high Mn. More than twice as much phosphorus was found in hydrolyzed, low-Ca nucleotide preparations than was present in those of plants receiving high Ca. Ca thus appears to affect the interconversion of organic and inorganic phosphorus. 8. Both Ca and Mn affected the number, concentration, and paper chromatographic properties of unknown fluorescing constituents obtained by anion-exchange chromatography. Adenosine, uridine, cytidine, and glucoseamine were tentatively identified. 9. Paper chromatograms revealed that the sugars glucose, maltose, and raffinose appeared in all peak U.V.-absorbing fractions. Glucoseamine and turanose were apparently present only in plants receiving both low Ca and low Mn. Results of this study suggest that Ca interacts with Mn in mineral absorption and enzyme effects, that Ca can alter known Mn X Si relationships, and that the consequences of variable Ca and Mn content are felt by the plant over a broad range of biochemical reactions.