SOMATIC EMBRYOGENESIS AND SHOOT DEVELOPME NT AS FUNCTION OF 2,4-D ANDBAP-CONCENTRATIONS IN ZYGOTIC EMBRYOS OF LATE FLUSHING PEDUNCULATE OAK (QUERCUS-ROBUR L)

A standard method for in vitro propagation of late flushing Quercus ro bur L was developed. Shoot induction on zygotic embryos as well as som atic embryogenesis was induced by a selective use of growth regulators . Shoot formation on zygotic embryos was induced by using modified WPM supplemented with 1 muM BAP + 1 muM 2,4-D and by using modified WPM s upplemented with 10 muM BAP. The use of modified WPM supplemented with 10 muM BAP led to an induction rate of 87,9%. In combination with 5 m uM 2,4-D shoot formation was already suppressed. The tested hormone co mbinations of 2,4-D and BAP induced somatic embryos on cotyledons of z ygotic embryos, however the induction rates differed strongly. The hig hest induction rate of 34,8% was achieved on modified WPM supplemented with 1 muM BAP + 1 muM 2,4-D. A total of 36 genotypes were establishe d by shoot formation on zygotic embryos and 17 genotypes were establis hed by somatic embryogenesis. Plant regeneration from somatic embryos was achieved with 7 of 17 genotypes.