Abstract
To establish a technique of obtaining azalea (Rhododendron spp.) seedlings precociously, ovules (immature seeds) from a diallel cross among 5 species and 1 variety were cultured in vitro. Adding 50 mg·liter-1 GA3 to the medium accelerated ovule germination, so that in the fastest case, 3 months after crossing (3 MAC) ovules from 20 crosses germinated, but the germination rates were low and less than 30%. When ovules 4 MAC were cultured, seedlings were obtained from all crosses ; more than 50% of seedlings from crosses with R. kiusianum and R. kaempferi as seed parents were obtained within 1 and 2 months after culturing. These results indicate that by exposing ovules of 4 MAC to 50mg·liter-1 GA3, one can obtain hybrid seedlings precociously ; the period from crossing to the seedling stage was 1.5 to 2.5 months shorter than with 6 MAC cultured seeds.
