Water-Solubility of Dry Matter in Relation to Calcium Nutrition of Normal Orange and Lemon Leaves

Abstract

1. The ash of normal citrus leaves of the same age shows practically no difference in composition for the citrus varieties examined. When the dry matter of these leaves is extracted with water, the ash and the calcium of the soluble fraction of mature normal Washington Navel and Valencia orange leaves are greater than those of Eureka lemon. 2. The water content of these leaves as a percentage of their fresh weight changes very little until after the leaves have reached their full size and have begun to mature. 3. The percentage of the total magnesium that is water-soluble is usually at a minimum at the time when the leaves have reached their full size and are still thin. 4. The percentage of the total sodium soluble in water decreases with increasing age of the leaves. Over 90 per cent of the potassium of the dry matter of citrus leaves is water-soluble. The water-soluble phosphorus of the dry matter decreases with increasing age of the leaves. 5. The relationship between the calcium nutrition of these citrus varieties and certain physiological characteristics is discussed to show the bearing the present paper has on the future direction of the investigation of citrus nutrition.