Initial stages in the course of adventitious bud formation on embryos of Picea abies

Adventitious buds on embryos of Picea abies (L.) Karst. developed after a pulse treatment with 250 μM benzyladenine (BA) of pH 5.5 for 2 h. Light and temperature regimes were not critical during the initial stages. Adventitious buds developed faster after a pulse treatment and the variation among different experiments was lower compared to when the embryos were cultured on media supplemented with BA. Various stages of the differentiation of adventitious buds were identified: stage 1 ‐ appearance of meristematic centres (approximately the first two weeks); stage 2 ‐ development of adventitious bud primordia (approximately the third week); stage 3 ‐ adventitious bud development (from approximately the 4th to the 8th week). This system may be used for further studies on bud differentiation.