カキ数品種の <i>in vitro</i> でのシュート増殖と発根

Abstract

Using 7 Japanese persimmon cultivars (‘Hiratanenashi’, ‘Jiro’, ‘Hana-gosho’, ‘Aizumishirazu’, ‘E-gosho’, ‘Kurogaki’ and 2 strains, normal and dwarf, of ‘Nishimura-wase’), optimal micropropagational conditions for culture establishment, shoot proliferation and rooting were investigated.1. For culture establishment, both the types (N6-Benzyladenine: BA or N6-Isopentenyladenine: 2iP) and concentrations (1_??_20mg•l-1) of cytokinin were tested with dormant bud explants of ‘Jiro’ and ‘Kurogaki’ on modified MS medium with nitrates reduced to half strength (MS(1/2 NO3)). Optimum concentrations of BA and 2iP for ‘Jiro’ were 5mg•l-1 and 5_??_20mg•l-1, respectively, and those for ‘Kurogaki’, 2_??_5mg•l-1 and 5-20mg•l-1. Explants of ‘Jiro’ produced more shoots than those of ‘Kurogaki’ during this stage and were established more easily. Other cultivars except ‘Hana-gosho’ could be established readily on the MS (1/2 NO3)medium supplemented with 5mg•l-1 BA.2. For shoot proliferation and elongation also, both the types (BA or 2iP) and concentrations (1_??_20mg•l-1) of cytokinin were tested with ‘Jiro’, ‘Aizumishirazu’, ‘E-gosho’, ‘Kurogaki’ and 2 strains of ‘Nishimura-wase’ explants which had been established and subcultured on MS (1/2 NO3) medium supplemented with 5mg•l-1 BA. BA was more effective for shoot proliferation, while 2iP was better for shoot elongation. In most cases, optimum concentration of each cytokinin was 5mg•l-1. The dwarf strain of ‘Nishimura-wase’ was more responsive to either cytokinin than the normal strain.3. For rooting, periods of dark treatment (0_??_15 days) and 3-indolebutyric acid (IBA) concentrations (0_??_1000mg•l-1)for acute exposure were tested with ‘Hiratanenashi’ shoots which had been elongated at 5mg•l-1 2iP in the MS (1/2 NO3) medium. More than 6 days of darkness enhanced rooting, with the highest rooting percent being 9 days of treatment. Optimum IBA concentration for rooting was 250mg•l-1. Shoot cuttings of 5 cvs, ‘Hiratanenashi’, ‘Jiro’, ‘Aizumishirazu’, ‘E-gosho’ and ‘Kurogaki’ rooted with final rootings of 96%, 80%, 74%, 44% and 8%, respectively, by this best combination of darkness and IBA treatment.