Early tree growth and high fruit productivity of ‘Saijo’ Japanese persimmon grafted on dwarfing rootstock of ‘Hourakudai’ persimmon

The Japanese persimmon tree ‘Saijo’ (Diospyros kaki Thunb.), which is pollination-constant astringent, grows vigorously and has a tendency to grow tall, which makes its height difficult to control. We compared the early growth and fruit yield of ‘Saijo’ scions grafted onto ‘Hourakudai’ dwarfing rootstock clones with those grafted onto standard (wild) seedling rootstocks (D. kaki var. sylvestris Makino) in the field under rain-shelter conditions. For our study, trees were cultivated with a central leader training system for 2 years after planting and then changed to an open center training system. From 2 to 5 years after planting, the tree height of ‘Saijo’ grafted onto ‘Hourakudai’ rootstocks was 63-71% those grafted onto standard seedling rootstocks. Tree canopy area and tree canopy volume of ‘Saijo’ grafted onto ‘Hourakudai’ rootstocks were 44-63 and 29-52% compared with those grafted onto standard seedling rootstocks, respectively. At 5 years after planting, the ‘Saijo’ scions of ‘Hourakudai’ rootstock trees had a higher fruit yield efficiency per scion trunk cross-sectional area (TCSA) and per tree canopy volume than those grafted onto standard seedling rootstocks. Fruit quality and average shoot lengths did not significantly differ between the two rootstock types. The scion-to-stock TCSA ratio of ‘Hourakudai’ was smaller than that of standard seedling rootstocks. These results indicated that ‘Saijo’ grafted onto ‘Hourakudai’ dwarfing rootstocks produced higher yield efficiency per scion TCSA and tree canopy volume without reducing fruit quality and shoot length.