Rooting treatment with 1-naphthaleneacetic acid to softwood cuttings of dwarfing rootstocks for persimmon

Recently, an efficient softwood leaf-bud cutting propagation of persimmon was developed, and indole-3-butyric acid (IBA) was used as an auxin for promoting rooting in almost all the persimmon cutting propagation. We examined the possible use of another auxin, 1-naphthaleneacetic acid (NAA), in cutting propagation of two dwarfing rootstocks for persimmon, ‘MKR1’ and FDR-1. Using quick-dip method, three concentrations of Na-NAA, water-soluble NAA, were tested for comparing the optimal concentrations of IBA, which were determined in the previous studies. Although the highest concentration treatment damaged some of the cuttings, the treatments to ‘MKR1’ cuttings in all Na-NAA concentrations tested induced rooting as effectively as the IBA 2000 mg L^‑1 treatment. The optimal concentration of Na-NAA seemed to be 5500 mg L^‑1, although there were no significant differences for rooting percentages between the auxin treatments. The rooting percentage of FDR-1 cuttings treated with Na-NAA 11000 mg L^-1 as well as with IBA 6000 mg L^‑1 seemed to be the highest, although there were no significant differences in the auxin-treated cuttings. Between the auxin-treated cuttings, there were no significant differences in the percentages of finished nursery stock, i.e. in the number of overwintering survival of rooted cuttings per the number of original cuttings. Therefore, our study indicated that NAA effectively induced rooting leaf-bud cuttings of dwarfing rootstocks for persimmon as well as IBA did.