| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1998: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1997: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Research Abstract |
Fruit trees become larger year after year because they are perennial woody plants. Large-sized trees impose farmers much labor in such practices as training, thinning, harvesting and sprays of agricultural chemicals. Therefore, small-sized trees have been worldwide preferred in orchards. In apples, many dwarfing rootstocks have been developed and extensively utilized in commercial production. In peaches, Prunus japonica and P.tomentosa have been used as their dwarfing rootstocks. The grafted trees often decline due to graft-incompatibility' several years after planting. In the absence of useful dwarfing rootstocks, it is necessary to develop alternative techniques for making tree sizes small. Ringing of trunk is effective to reduce the tree vigor. Unless reunion of the ringed parts occurs, the trees eventually die. We tried partial ringing and spiral ringing of trunk for reducing trees size by using young peach trees. Neither partial ringing of 2/3 circumference nor single spiral ringing is effective but complete ringing, double and triple spiral ringing reduced the tree size. However, severe ringing such as complete ringing and double spiral ringing caused three trees and one (out of five) to die, respectively. Flower bud formation was favored by reducing tree size. Rate of sap flow through the trunk was closely related with tree vigor. In another experiment, trunk was cut half transversely to examine its effect on fruit quality of satsuma mandarin. Fruit bearing on shoots on the cut-side of trunk were greatly affected. Brix content in the juice was higher in fruit on the cut side than on the non-cut side and control trees. Flower bud formation was also promoted only on the cut side. Sap flow was prevented in both the lower and upper parts of trunk on the cut side.
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