SOMATIC EMBRYOGENESIS FROM IMMATURE AND MATURE ZYGOTIC EMBRYOS AND FROM COTYLEDONS AND NEEDLES OF SOMATIC PLANTLETS OF LARIX

Induction of embryonal masses was achieved from full-sib immature zygo tic embryos of Larix decidua Mill., Larix x eurolepis A. Henry, and La rix X leptoeuropaea, and it was found to be affected by the developmen tal stage of the embryos. Furthermore, the explant response depended o n a specific combination of parental trees used for production of seed s. For the first time, induction was successful in L. decidua with mat ure zygotic embryos. These embryos were isolated from one of the three seedlots tested and induction frequency was 5%. Mature somatic embryo s of L. x leptoeuropaea expressed an initiation frequency of 83%. Coty ledons and needles of plantlets derived from somatic embryos of L. xle ptoeuropaea were used as explants to induce somatic embryogenesis at a frequency of 8 and 3%, respectively. A cytokinin pretreatment seemed to enhance the frequency of induction. Mature somatic embryos were obt ained from embryonal masses derived from explants of different ontogen ic age. Future opportunities of research into the induction of embryon al masses from mature tree tissues are discussed.