Effects of degrees and removal of lateral branch strapping with covered insulated wires on fruit growth and return-bloom in persimmon 'Kazusa'

Experiments were conducted to analyze the effect of degrees and removal of lateral branch strapping with covered insulated wires 2 mm in diameter (partial girdling) on fruit set, fruit growth and return-bloom in persimmon cv. Kazusa 10 years old trees. The treatments of lateral branch strapping were follows five; (1) S.R (strapping in I mm depth and removal) , (2) S.NR (strapping in I mm depth and non-removal 2 month after strapping, (3) SS.R (strong strapping in 2 mm depth and removal) , (4) SS.NR (strong strapping in 2 mm depth and non-removal 2 month after strapping, (5) control (non-strapping) . Treatments were carried out at full bloom. 1 . Percentages of fruit set and fruit growth rate were increased by four strapping treatments (S.R; S.NR, SS.R and SS.NR) in contrast with the control. 2. Fruit growing days to harvest in the control was 201 and those in S.R , S.NR , SS.NR , SS.R and SS.NR were shorter 9 , 3 ,12 and 6 days than that in the control, respectively. At harvest, fruit weights of the control was 202 g and those in S.R , S.NR , SS.NR , SS.R and SS.NR were heavier 39, 27, 16 and 10 g than that of the control, respectively. 3. Percentages of the leaf dry weight and specific leaf weights in four strapping treatments were both higher than those of the control from June to July. 4. At the beginning of January, total number of flower-bud in terminal, the third, the fifth and the seventh bud of non-bearing shoot in four strapping treatments were about five times as much as the control. Carbohydrate content and C/N ratio of non-bearing shoot in four strapping treatments were both higher than those of the control. 5. In the following spring, percentages of shoot with flower in each four strapping treatments were 3 - 4 times as much as control and numbers of flower in each four strapping treatments were 5 - 9 times as much as control. Therefore, the numbers of harvest fruit in each four strapping treatments were remarkably increased as compare of control. 6. On S.R treatment, groove by removal of covered insulated wires was healed during about l month and the degrees of suppression of shoot length in S.R treatment was more gently than those in other three strapping treatments of S.NR , SS.R and SS.NR. Therefore, S/R treatment was most suitable methods for fruit growth promotion and return-bloom comparison with other three methods of S.NR, SS.R and SS.NR .