IN NATURE DORMANT BUDS AND IN-VITRO DORMANT-LIKE BUDS OF FRAXINUS-EXCELSIOR L

Microcuttings of Fraxinus excelsior, sampled from adult trees during t he period of cell cycle blockage of bud in G(0-1), developed long reju venated sprouts on the Woody Plant Medium (WPM) with benzylaminopurine (BAP) (4.0 mg/l) and indolebutyric acid (IBA) (0.03 mg/l) These sprou ts had the ability to enter a resting period, building dormant-like bu ds when maintained on the original WPM. Sprouts developed from subcult ures also entered a resting period without any transfer. Comparison of in nature buds in active growth and dormancy with buds of growing spr outs and in vitro dormant-like buds revealed similarity in behaviour a t the shoot apical level. In particular, in dormant-like buds in a con stant environment, shoot apical functioning was suppressed while the c ell cycle of the shoot apex was blocked at the G(0-1) phase, like in n ature dormant buds.