Orchard growth, flowering and fruiting of 'Fuyu' and 'Hiratanenashi' Japanese persimmon trees grafted on potentially dwarfing rootstocks propagated by cutting.

摘要

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.