Seasonal uptake of phosphorus, potassium, calcium and magnesium by young peach trees

Abstract

Two-year-old peach trees, grown in sand culture were destructively sampled over a period of 14 months, to determine the uptake of phosphorus, potassium, calcium and magnesium in the new growth (leaves, fruit and new shoots) and in the permanent structure (roots, wood and bark). Samples were taken at three-weekly intervals and the accumulation during five distinct phenological stages, i.e. bud-break, termination of shoot elongation, harvest, commencement of leaf fall and completion of leaf fall, was examined. The total content of these elements increased from bud-break or shortly afterwards, through the period of shoot elongation until harvest. P content again increased during the leaf-senescence period, while Ca content increased initially but declined sharply during leaf fall, which lasted six weeks. Mg content declined rapidly during this period. K content declined after harvest, remained constant for a period and then declined rapidly during the leaf-fall period. The leaves of the young peach tree contained the largest proportions of the K, Ca and Mg content in the tree. Leaf fall therefore accounted for most of the losses during the leaf-fall period. Peach fruit contained relatively large quantities of K which were removed during harvest.