Effects of Shoot Pinching before Anthesis on Fruit Development, Flower Bud Formation and Dry Matter Production in Japanese Persimmon Trees (Diospyros kaki Thunb.) under Restricted Root Zone Volume

Abstract

Shoots of three-year-old cv. Tonewase and Shinsyu trees under restricted root zone volume were pinched 8-10 days before full bloom (FB), leaving 10 leaves per shoot from their basal part. Lateral buds were repinched at their basal part soon after sprouting. Total shoot lengths per tree and average shoot lengths were shorter in the pinched trees as compared with the nonpinched trees in both cultivars. Shoot pinching did not affect yields per tree, but increased average fruit weights in both cultivars. In Shinsyu trees, shoot pinching decreased total soluble solids contents (TSS) of fruit. On both cultivars, there was little influence on flower bud formation on the mother branch. Shoots of three-year-old cv. Sosyu under pot culture were pinched the 27 days before FB, leaving 8 leaves per shoot. Shoot pinching increased the yields per tree and the average fruit weights, but did not affect fruit quality. There was no correlations between fruit weight and shoot growth in either the pinched trees or the non-pinched trees. Shoots of three-year-old cv. Fuyu trees under pot culture were pinched 2 days before FB at different intensities of pinching. Shoot pinching decreased total shoot lengths per tree, average shoot lengths, leaf numbers, leaf weights and leaf areas per tree. Shoot pinching increased average fruit weights under both intensities of pinching. There were no differences in yields per tree and TSS between the appropriately pinched trees and non-pinched trees, whereas those of the severely pinched trees were inferior to those of non-pinched trees. Shoot pinching did not affect the annual dry matter gains per unit leaf dry weight and per unit leaf area. The ratio of assimilates partitioned into fruit were higher, whereas those into older wood, shoot and fine root were lower in the appropriately pinched trees compared with those in the non-pinched trees.