Orchard Growth, Flowering and Fruiting of 'Fuyu' and 'Hiratanenashi' Japanese Persimmon Trees Grafted on Potentially Dwarfing Rootstocks Propagated by Cutting

The field performance of 'Fuyu' and `Hiratanenashi' Japanese persimmon (Diospyros kaki Thunb.) trees grafted onto rootstocks propagated from cuttings of root suckers of dwarfed trees (R-a and R-b) was investigated over seven years. The results were then compared with the performance of trees grafted onto seedling stocks (S) as well as that of micropropagated and own-rooted trees (O-R). Shoot growth of both cultivars on R-b was less vigorous than that on R-a, while tree height of 'Hiratanenashi' on R-a was the same as that of both S and O-R. Secondary shoots on R-b trees were scarce in both cultivars in the fifth and sixth years. On R-b, both cultivars bore flowers soon after field establishment and thereafter continued to do so abundantly, with the percentage of flower-bearing shoots on R-b trees being the highest for each study year. Yield efficiencies calculated by units of trunk cross-sectional area, canopy area, and canopy volume showed that R-b trees produced fruit most effectively, although the total yields during the three harvest years were not significantly different between rootstocks. The appearance of the graft union with R-b varied depending on the scion cultivar, but no union was damaged by the occurrence of several typhoons, which uprooted a number of trees. These results show the possibility of using R-b propagated by cutting as a dwarfing rootstock for persimmon trees. Overall, the R-b rootstock improved yield efficiency, although fruit quality requires further investigation because it is thought to be affected by rootstock type.