HIGH-FREQUENCY DIRECT SOMATIC EMBRYOGENESIS IN THIN-LAYER CULTURES OFHYBRID 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-benz ylaminopurine, but the number of embryos was much less in the latter t han with TDZ. The development of somatic embryos in cultures of thin l ayers was rapid and the number of embryos was about eightfold higher t han in cultures of whole hypocotyl explants. Thin layer explants of 1- week-old seedlings produced a high number of somatic embryos than thos e obtained from older seedlings. The cultivar Scarlet Orbit Improved s howed better regeneration potential than 'Sprinter Scarlet'. There wer e no visible differences in total number of somatic embryos produced i n 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 p lantlets within 6 to 8 weeks of culture initiation.