This study was conducted from 2010 to 2012 to understand the effect of differential pruning cuts in the lateral branch on shoot growth and fruit characteristics of ‘Fuyu’ persimmon (Diospyros kaki). The winter pruning treatments consist of (1) no pruning, (2) terminal bud removal (TBR), (3) shoot tip removal (STR), and (4) terminal bud removal + shoot tip removal (TBR+STR). After winter pruning on the lateral branch, the characteristics of shoot growth and fruit quality were measured.
The numbers of shoots in no pruning treatment were larger than in its other pruning cuts and then the total shoot length of lateral branch was larger than its other pruning cuts. However, the number of leaves of the shoot in the lateral branch was similar to all other treatments. In the case of the leaf area, no pruning treatment showed the lowest leaf area at 373.3cm2.
Although the proximal diameter of lateral branch in TBR+STR treatment was higher than its other pruning cuts, the number of shoots after winter pruning was low compared to no pruning treatment. The number of shoot and average leaves were significantly different, while the length and leaf area were not significantly different among the pruning cuts. Thus, all pruning cuts showed the similar leaf area and the length of shoot in the lateral branch.
The number and dry weight of flower buds on the shoot after winter pruning were not significantly different. The number of flower buds on shoot was 14.5 with no pruning, 10.0 with STR, 9.0 with TBR+STR, and 8.0 with TBR, respectively. The number of bearing shoots was similar to the number of flower buds in the lateral branch. However, the dry weight of flower buds on the shoot was the highest with TBR treatment.
In fruit characteristics, the firmness and soluble solids content of fruit were not significantly different, while the fresh weight was higher in the order of TBR+STR, STR, TBR, and no pruning. The results considered that the removal of shoot tip and/or terminal buds increased the outbreak of regular shoots in the lateral branch and helped to distribute the assimilation products in the tree, thus contributing to stabilize the tree vigor and increase fruit quality.
It is concluded that the removal of shoot tip and/or additional terminal bud removing of lateral branch should help to increase fruit quality with delaying the expansion of tree crowns and maintaining tree vigor.