THE INFLUENCE OF ROOTSTOCK ON THE MINERAL COMPOSITION OF VALENCIA ORANGE LEAVES

Abstract

Valencia buds on 6 different understocks were grown in a random-plot arrangement on a typical Florida citrus soil designated as Lakeland fine sand. Uniform applications of mixed fertilizers (containing N, P, K, Ca, Mg, Mn, Zn, Cu and B) were made thrice annually for 5 yrs. Trunk circumference measurements showed that the rootstock significantly affected tree size in the following order: rough lemon, Rusk citrange, sweet orange, Cleopatra mandarin, Bowen grapefruit, sour orange. Foliar analyses showed that the absolute amount of N per leaf was directly correlated with tree size. No other element was consistent in this respect, although significant differences in the percentages of N, P, K, Ca, Mg, Mn, Zn, Cu and B in the leaves were induced by different rootstocks. The % of Na in the leaves was not affected. The more vigorous trees tended to accumulate higher percentages of most of these elements than did the less vigorous. The understock influenced the concn. of the micro-nutrient elements more profoundly than it did the macro-nutrient elements.