MANIFESTATION OF EMBRYOGENIC POTENTIAL IN CULTURE OF ZYGOTIC EMBRYOS OF QUERCUS-ROBUR L

For the initiation of somatic embryogenesis early cotyledonary stage o f zygotic embryo explants (from 15th July until late August) was suita ble. The highest frequency of differentiation of somatic embryos was o btained on cotyledons of zygotic embryos cultured on basal modified me dium MS (with 1/2 concentration macronutrients) or WPM medium containi ng 500 mg.l(-1) glutamine, proline and casein hydrolysate and suppleme nted with 2,4-D (1,0-2,0 mg.l(-1)) and BAP (0,5-1,0 mg.l(-1)). The dev elopment of somatic embryos was direct and indirect and the process wa s continuous over a long period. Primary somatic embryos were able to produce secondary embryos. Repetitive somatic embryogenesis led to the proliferation of a large number of new somatic embryos on their cotyl edons, hypocotyl or radicula. The process of embryo differentation is asynchronous - various stages of somatic embryos could be observed in embryogenic culture. A somatic embryo conversion was rare on tested me dia. Embryo germination occured on medium containing BAP (0,1 mg.l(-1) ) or on medium with ABA and GA(3) (each 0,2 mg.l(-1)) after a previous culture on WPM medium without plant growth regulators supplemented wi th sorbitol (6%). The embryo germination occurred also on WPM medium w ith 0.2 mg.l(-1) BAP when cultures were mantained at 2 degrees C for 4 weeks. Only 8 somatic embryos developed into plantlets. Their transpl antation to in vivo conditions was unsuccessful.