Abstract
The factors influencing rooting of softwood cuttings of two cultivars, 'Jiro' and 'Nishimurawase', of Japanese persimmon (Diospyros kaki Thunb.) were studied. The cuttings from the root suckers of micropropagated trees rooted best, followed by those from the shoots of micropropagated trees and grafted trees in that order. Except for the cuttings from grafted trees, the shorter the cuttings, the higher the rooting percentage. When planted in late June, the single bud, leafy cuttings (leaf-bud cuttings) taken from the root suckers and treated with indole-3-butyric acid (IBA), 70% or more rooted well. When planted in late July or late August, however, less than 40% of the leaf-bud cuttings rooted. Comparable cuttings without IBA treatment scarcely rooted when planted in late June, and did not root at all when planted in late July or late August. There was no significant difference in the rooting capacity between the two cultivars. Almost all leaf-bud cuttings from the root suckers survived during the experimental period (60 days), although those from the shoots of grafted trees died gradually ; none of the 25-cm cuttings from the root suckers survived 25 days after planting. The vascular cambium at the base of leaf-bud cuttings from the root suckers began to divide actively soon after planting. Callus formed in the phloem and cortex of the cut surface and developed extensively. However, active cell division was not observed at the bases of leaf-bud cuttings from the shoots of grafted trees nor 25-cm cuttings from the root suckers. Initial cells of the adventitious root produced in the vascular cambium of the leaf-bud cuttings from the root suckers were first observed 20 days after planting ; they developed to roots and emerged 30 days after planting.
