HIGH-FREQUENCY DIRECT SOMATIC EMBRYOGENESIS IN THIN-LAYER CULTURES OF HYBRID SEED GERANIUM (PELARGONIUM X HORTORUM)

Thin layer explants from the hypocotyls of young seedlings of geranium (Pelargonium x hortorum Bailey) produced somatic embryos in response to thidiazuron (TDZ) or a combination of indoleacetic acid and N6-benzylaminopurine, but the number of embryos was much less in the latter than with TDZ. The development of somatic embryos in cultures of thin layers was rapid and the number of embryos was about eightfold higher than in cultures of whole hypocotyl explants. Thin layer explants of 1-week-old seedlings produced a high number of somatic embryos than those obtained from older seedlings. The cultivar Scarlet Orbit Improved showed better regeneration potential than 'Sprinter Scarlet'. There were no visible differences in total number of somatic embryos produced in the medium containing sucrose or glucose. The addition of glutamine to the induction medium further improved the number of somatic embryos that developed. Regenerated somatic embryos developed into complete plantlets within 6 to 8 weeks of culture initiation.