Manganese, copper and molybdenum nutrition of papaya

Abstract

Papaya cv Honeydew, was grown in refined sand with complete nutrition and with deficiency levels of Mn, Cu and Mo. Deficiency symptoms of Mo and Cu were induced earlier than those of Mn. Depressions in growth and dry matter were less marked with Mn deficiency than with those of Mo and Cu. Mn, Cu or Mo deficiencies decreased the tissue concentrations of the deficient element and the specific activity of catalase, and increased the activities of peroxidase and ribonuclease. The specific activity of acid phosphatase was stimulated and that of cytochrome-c oxidase was depressed by deficiency of Mo or Cu. In addition to reduced soluble protein caused by deficiencies of Mn, Cu and Mo, the specific activity of nitrate reductase was depressed in the leaves of Mo-deficient plants.