EFFECT OF EXOGENOUS CYTOKININS, APPLIED IN THE PROLIFERATION PHASE, ON THE ROOTING PERFORMANCE OF KIWIFRUIT: THE CASE OF CPPU AND BA

In this work, the indirect effect of the use in the multiplication phase of different cytokinins, BA (Benzyladenine) or CPPU (N-(2-chloro-4-pyridyl)-N-phenylurea), on the rooting response of in vitro microcuttings of Actinidia chinensis, Planch (sel K190) and A. deliciosa A. Chev. (Cultivar Hayward and Tomuri), was investigated. Microcuttings prepared from cultures maintained for 1 subculture on 4.4 μM BA or CPPU were transferred directly into a rooting medium or transferred to a hormone free medium for an elongation phase and then transferred to the rooting medium. Higher rooting percentages were obtained with the explants previously grown in BA than in those multiplied on CPPU and directly transferred to the rooting medium. The elongation phase reduced the rooting response in explants coming from sub-culturing on BA, while the transferring to a hormone free medium for a sub-culture was necessary with CPPU for increasing root induction. Differences in total chlorophyll and phenols were detected between BA and CPPU while no significative changes were detected in the water content.