Alternating Cytokinins in Multiplication Media Stimulates in Vitro Shoot Growth and Rooting of Eucalyptus globulus Labill.

Shoots of Eucalyptus globulus Labill. cultured on shoot multiplicationmedia containing, on alternate subcultures, 6-benzylaminopurine(BAP) or 6-furfurylaminopurine (kinetin), showed better growththan cultures in which either of the cytokinins was used continuously,or both were used in an equimolar mixture. When BAP was usedcontinuously in the medium (i.e. in every subculture), shootsmultiplied but remained stunted and leaves became red and abscised.Kinetin or 6-dimethylallyaminopurine (2iP) used continuouslyin the medium induced very low multiplication but the shootsdid not become red nor did the leaves abscise. Shoots takenfrom multiplication medium containing BAP and placed on rootingmedium with 10 µM indole butyric acid (IBA) produced fewroots and often died while on the rooting medium. In contrast,shoots from the multiplication medium containing kinetin producedmore roots and remained healthy during the passage on the rootingmedium.Copyright 1994, 1999 Academic Press Eucalyptus globulus, Tasmanian bluegum, cytokinins, micropropagation, in vitro rooting