Rooting effects of NAA treatment on cuttings of persimmon dwarfing rootstock ‘Hourakudai’ and growing conditions for grafted scions

Persimmon (Diospyros kaki Thunb.) is generally difficult to propagate by cuttings, so commercial production of saplings is produced by grafting on seedlings. ‘Hourakudai’ is a recently developed dwarfing rootstock and can be rooted by cuttings with IBA treatment. To investigate the appropriate cutting planting time and the optimal concentration of the commercial 1-naphthaleneacetic acid (NAA) for the softwood cutting of ‘Hourakudai’, shoots contained one or two leaves were treated with NAA diluted 3667 or 5500 ppm, and then planted in mid- and late June under mist irrigation. After three months of planting, survival and rooting success of the cuttings were measured. By following year, rooted cuttings were grafted, and the growth was observed under different potting conditions (1.5-L, 10-L, and 20-L). Between the two concentrations, the best rooting was obtained in the treatment of 5500 ppm NAA planted in late June. The growth of the grafted plant in the following year increased in proportion to the volume of the pot. The 20-L pots produced the longest shoots and 100% graft success.