ROLE OF PLANT HORMONES IN LATERAL BUD GROWTH OF ROSE AND APPLE IN VITRO

The effects of different growth regulators and inhibitors on sprouting and outgrowth of isolated axillary buds of rose and apple in vitro were evaluated. Budbreak in ‘Madelon’ rose was stimulated by benzyladenine (BA). The response was dependent on the original position of the axillary bud on the main stem. Using a gas-permeable closure, shoot length was increased in ‘Madelon’ but not in ‘Motrea’ rose, suggesting an inhibiting effect of accumulating ethylene. Addition of silverthiosulphate (STS), an inhibitor of ethylene action, increased shoot length significantly in both rose varieties and in apple. In apple, the stimulating effect of STS depended upon the auxin concentration in the medium. Inhibiting ethylene biosynthesis with aminoethoxyvinylglycine (AVG) or stimulating it with 1-aminocyclopropane-1-carboxylic acid (ACC) had no effect on average shoot length in rose. Only in ‘Madelon’, the presence of ACC decreased the multiplication rate. Abscisic acid (ABA) reduced or inhibited BA-induced prouting of isolated axillary buds of ‘Madelon’ rose.