1975 Volume 43 Issue 4 Pages 368-376
The present experiment was carried out to estimate optimum degree of fruit thinning, using persimmon cultivars"Jiro, Monpei and Hiratanenashi", and a pear"Chojuro". The number of harvested fruits per one square meter of leaf area was counted on each tree for representing the fruit load ratio which was recognized as a major factor influencing the individual fruit weight.
1. The mean fruit weight per tree showed a negative correlation to the fruit load ratio, though it attained to a maximum when the fruit number per one square meter of leaf area was decreased to about two to three fruit in persimmon. Thus, the fruit load ratio at which the mean fruit weight attained to a maximum, was considered to be the upper limit of degree of thinning effective for promoting fruit enlargement.
The fruit yield per unit leaf area had a positive correlation to the fruit load ratio. The coefficient of variation of fruit weight differed slightly among trees, but the fruit load ratio did not exhibit distinctive effect on it.
2. Marketable fruits are required to exceed a certain size and weight; the lowest limit of weight for marketable fruit in all varieties of persimmon is 136g, and that in"Chojuro"pear is 195g.
For calculating yield of marketable fruits an equation was established from three main factors such as correlations of fruit yield and mean fruit weight to the fruit load ratio, and coefficient of variation of fruit weight. The quantity of marketable fruit differed depending upon the coefficient of variation of fruit weight. Even though the fruit yield per unit leaf area was the same, the larger became the coefficient of variation of fruit weight, the smaller quantity of marketable fruits there was.
3. The optimum range of fruit load was estimated by considering the fruit size and the yield of marketable fruits. The method of estimation of optimum fruit weight was established by considering the gross income and yield of marketable fruits.