Seasonal Trends in Concentration of Nitrogen, Phosphorus, Potassium, Calcium, and Magnesium in Leaf Portions of Apple, Blueberry, Grape, and Peach1

Abstract

Abstract Concentration of N, P, K, Ca and Mg in foliage samples every 3 weeks starting in mid May was determined. Prior to analysis, leaf blades were separated into margin and midrib portions and the petioles of apple (Malus domestica Borkh) and muscadine grapes (Vitis rotundifolia Michx) were removed and analyzed separately. Differences were evident in the concentration of N, K, and Mg between portions of the leaf blade in each of the plants analyzed. Leaf blade portions of highbush blueberry (Vaccinium corymbosum L.) or grape did not differ in P concentration. Changes in the concentration of an element within a portion of the leaf were normally accompanied by similar changes in the other portion or portions. Notable exceptions were the marked increases in grape petiole Ca and Mg during mid and late season with much less change in leaf blade content. Ca appeared to accumulate in the midrib portion to a much greater extent than the leaf margin portion of peach (Prunus perisca (L.) Batsch). The only indication of a late season mobilization of an element from the leaf margin was the decrease in N in the margin and a concurrent increase in themidrib portion of peach leaves.