Current Shoot and Leaf Growth in Japanese Persimmon, Diospyros kaki cv. Fuyu, in Relation to the Development of the Tissue System in the Leaf

Abstract

The growth of vegetative organs in Japanese persimmon, Diospyros kaki cv. Fuyu, was investigated by examining the growth rates of the current shoots and leaves. Leaf growth was related to development of the tissue systems.
The development of current shoots, in terms of elongation and weight, was different according their position on the mother shoot (two year old branches), with distal shoots displaying greater development than proximal shoots. The rate of both elongation and growth in fresh weight of the shoots was highest in early May, and declined rapidly thereafter. The rate of dry weight growth peaked in mid-May.
Leaf area increased markedly during the early stage of shoot development (mid-May), and the rate of leaf area growth declined in late May. The increase in fruit diameter growth typically commenced in mid-June, one to two weeks after the leaf area maximum was attained. The growth of basal leaves both began and finished earlier than that of upper leaves, even though the surface areas of leaves in upper positions were generally larger. The maximum growth rate in whole-leaf dry weight appeared in late May, thereafter decreasing throughout the growing season.
Shoots began to decline in dry matter percentage immediately after the start of shoot elongation, until mid-May. Thereafter the dry matter percentage of the shoots increased markedly until early July, and continued to increase gradually until the ripening stage. On the other hand, the dry matter percentage of the leaves was low during the period from leaf opening to mid-May, and increased gradually until early July. The maximum growth rate of the fruit, in terms of fresh weight, appeared in mid-July, about two weeks behind the maximum in the dry matter percentage of the leaf.
Development of the mesophyll (palisade and spongy tissue) was almost completed by mid-June, when the leaf surface area on the shoots had attained a maximum. The development of vascular tissues, especially xylem, in both the petiole and midrib began simultaneously after leaf opening, and was nearly finished by mid-June, about two weeks after the maximum in leaf area.