[Show abstract][Hide abstract] ABSTRACT: Crossability among seven evergreen azaleas (Rhododendron spp.) in subsection Tsutsui was compared. Capsule set was observed in all the crosses. Numver of seeds per cupsule was lower in the cross with R. kiusianum or R. serpyllifolium than in other crosses, and small flofers with short style andsmall ovary may be the reason for lower number of seeds. Number of seeds per cupsule was maximum when male/female style length ratio(SLA) was around 0.7. The number gradually decreased as the increase of SLA, and above 2.2 of SLA resulted in <200 seeds per cupsule. The seeds germinated very well in the most crosses. In the crosses with R. serpyllifolium, however, unilaterial cross incompirablility was observed.
[Show abstract][Hide abstract] ABSTRACT: In vitro multiplication of Alocasia micholitziana 'Green Velvet', Alocasia×amazonica and Alocasia cuculata was achieved from axillary bunds excised from the cormes of greenhouse-grown plants. Shoots were developed directly within 6-8 weeks on the MS medium supplemented with 10mgl[-1] 2-iP for A. micholitziana 'Green Velvet' or 10mgl[-1] BA for A. ×amazonica and A. cuculata. Considering the quality of the shoots, high frequency of shoot regeneration was achieved on similar medium in subsequent sebcultures for A. micholitziana 'Green Velvet' (5.0 shoots/calture) . Five mgl[-1] BA gave the best shoot regeneration in A. × amazonica and A. cuculata (4.6 and 5.0 shoots/culture, respectively). Acclimatization was successful with approximately 100% of the in vitro plantlets which survived in a greenhouse. The regenerated plants seemed morphologically to be similar to the respective mother plants. The established procedure provided a basic technique to carry out the future in vitro experiments in Alocasia.
[Show abstract][Hide abstract] ABSTRACT: Pollen viability of intersubgenetic hybrids between evergreen and deciduous azaleas was much lower than that of their parents. No capsule set in the crossings with the hybrids when used either as seed or pollen parents. In vitro chromosome doubling with oryzalin was attemped for restoring the fertility of the hybrid. Survival rates of the explants were more than 50% in oryzalin treatments, though high concentration and long term treatments brought the survival rates and number of shoots per explant low, under which number of shoots per explant also decreased. Twenty tetraploid and 28 mixploid (2x+4x) plants were obtained by the treatments from 123 individuals. The most suitable conditions for obtaining tetraploids appared to be 0.01% oryzalin treatment for 48 hours.