The effect of indolyl-3-butyric acid (IBA) and paclobutrazol (PP 333) on the rooting of shoots of the Ishtara peach rootstock was examined in in vitro conditions in light. In the first stage of the experiments the effect of the IBA concentration (0, 0.75, 1.5 mg/l) was studied and in the second stage the effect of the interaction of IBA (0.75 mg/l) and PP 333 (0.06 and
0.12 mg/l) in the MS medium, which is optimal for the rooting of the peach rootstock Ishtara. During shoot cultivation we evaluated root formation (average length and number). During rhizogenesis the production of ethylene, ethane and CO₂ by the shoots and the level of abscisic acid (ABA) in the shoot base was monitored in in vitro conditions. Shoots cultivated on the MS medium with
1.5 mg/l of IBA produced the highest number of roots and the longest roots that produced the lowest level of ethylene and CO₂ and the level of ABA was the lowest in the bases.