Factors affecting fruit weight of Japanese persimmons (Diospyros Kaki LINN. f.)

Abstract

1. This investigation was carried on from 1960 to 1963 with three varieties of Japanese persimmons (Jiro, Monpei and Hiratanenashi) to make clear the main factors connected with the yearly change of the average individual fruit weight of a tree. Fruits were thinned usually to one per bearing shoot in July of each year, except for on some of trees in 1963.2. When the correlation was observed between shoot length and leaf area, and between leaf number and leaf area respectively, its coefficient was higher in the former than in the latter. Consequently, fruit number per one meter length of shoot was employed as an indicator of fruit load on a tree, dividing the total number of fruits by the total length of non-bearing and bearing shoots.3. A significant negative correlation was always found between fruit load of a tree and average individual fruit weight. However, a significant positive correlation existed only occasionally, both between bearing shoot length and average individual fruit weight, and between seed number of a fruit and average individual fruit weight. Therefore, the fruit load of a tree seemed to have a deeper connection with the average individual fruit weight than the length of a bearing shoot and the seed number of a fruit.4. Average individual fruit weight varied from 150 to 250g in the yearly change of the same tree as well as among the different trees of the same year. The variation coefficient expressed as a measure of dispersion of individual fruit weights was 7 to 15% regardless of the fruit load. A significant positive correlation was always found between fruit load of a tree and its yield.