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

Abstract

Shoots of Eucalyptus globulus Labill. cultured on shoot multiplication media containing, on alternate subcultures, 6-benzylaminopurine (BAP) or 6-furfurylaminopurine (kinetin), showed better growth than cultures in which either of the cytokinins was used continuously, or both were used in an equimolar mixture. When BAP was used continuously in the medium (i.e. in every subculture), shoots multiplied but remained stunted and leaves became red and abscised. Kinetin or 6-dimethylallyaminopurine (2iP) used continuously in the medium induced very low multiplication but the shoots did not become red nor did the leaves abscise. Shoots taken from multiplication medium containing BAP and placed on rooting medium with 10 microM indole butyric acid (IBA) produced few roots and often died while on the rooting medium. In contrast, shoots from the multiplication medium containing kinetin produced more roots and remained healthy during the passage on the rooting medium.