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Effect of Low Levels of Calcium on Exudation of Sugars and Sugar Derivatives from Intact Peanut Roots under Axenic Conditions ¹

^a Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

The effects of 10, 20, 35 and 50 mg of Ca²⁺ per liter on the qualitative and quantitative exudation of sugars from roots of 5-week-old peanut plants, Arachis hypogaea L., grown axenically in nutrient solutions, were measured. Nutrient solutions in which plants had been growing were collected at weekly intervals for 4 weeks, sugars in them were measured by gasliquid chromatography of the trimethylsilyl derivatives. Arabinose, ribose, xylose, fructose, mannose, glucose, galactose, mannitol, galacturonic acid, inositol, sucrose, and five unknowns were found. Qualitative and quantitative differences in exudates were correlated with age of the plants and calcium level. Four times more sugar was exuded at 10 mg than at 50 mg of Ca²⁺ per liter but no significant differences in growth were observed. Ion efflux measurements suggested that low levels of Ca²⁺ increased root cell membrane permeability.

¹ This work was supported in part by Plant Science Division, Agriculture Research Service, United States Department of Agriculture under Cooperative Agreement 12-14-100-9711(34). This is a portion of research presented by the senior author in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Contribution No. 226, Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg, Va. 24061.