THE DIFFERENTIAL EFFECT OF N6-BENZYL-ADENINE AND N6-(DELTA(2)-ISOPENTENYL)-ADENINE ON IN-VITRO PROPAGATION OF PEONIA-SUFFRUTICOSA ANDR IS CORRELATED WITH DIFFERENT HORMONE CONTENTS

N6-benzyl-adenine (BA) enhanced phyllogenesis and axillary bud develop ment of Paeonia suffruticosa during in vitro culture allowing good pro pagation while N6-(DELTA2-isopentenyl)adenine (iP) did not. During the first five days of culture, the mitotic activity of BA-treated explan ts was higher than in the iP-treated ones. High BA levels were detecte d in the BA-treated explants, and this was correlated with the absence of or the low indole-3-acetic acid (IAA) content. The low iP levels m easured in iP-treated explants were correlated with high endogenous IA A content; the new cytokinin/auxin ratio could explain the lack of axi llary buds and the development of only one leaf. Abscisic acid (ABA) w as detected neither in the controls nor in the cytokinin-treated expla nts during the first week. However, intensive restoration of ABA accum ulation was observed in controls from the third week onwards. Both BA and iP-treated explants accumulated less ABA than the controls but thi s hormone appeared later in the BA-treated explants than in the iP-tre ated ones.