DEVELOPMENT OF AN EFFICIENT MICROPROPAGATION PROTOCOL FOR EUCALYPTUS HYBRID (E. UROPHYLLA × E. GRANDIS) THROUGH AXILLARY SHOOT PROLIFERATION

Abstract

Eucalypts, in the family of Myrtaceae, are a fast-growing timber able to adapt to marginal environments. In Malaysia, the Eucalyptus hybrid (E. urophylla × E. grandis) is becoming popular for plantation as it is more tolerant to disease and produces a straight bole. Micropropagation of axillary shoots from a healthy Eucalyptus hybrid mother tree was evaluated for shoot proliferation in Murashige and Skoog (MS) basal media and woody plant media (WPM), supplemented with 0.1, 0.5, 1.0, 2.0 and 3.0 mg L-1 6-benzylaminopurine (BAP), singly or in combination with 0.5, 1.0 and 2.0 mg L-1 1-naphthaleneacetic acid (NAA). The WPM and MS basal media supplemented with 0.1 mg L-1 BAP were found suitable for shoot multiplication as both media induced the production of new shoots and shoot elongation. Higher concentration of BAP and NAA produced stunted axillary shoots. Regenerated shoots were evaluated for root growth in half strength MS basal media supplemented with indole-3-butyric acid (IBA) or NAA at concentrations 0.5, 1.0, 2.0 and 3.0 mg L-1. Root produced and root lengths were not significantly different among media formulation, and it was observed that 0.5 mg L-1 IBA in ½ MS basal medium gave the best overall root production. Healthy regenerated plantlets were acclimatised in a weaning chamber for one month, and then planted in polybags filled with baked soil and peat moss (1:1). The plantlets were watered twice a day and kept under 50% shade in the nursery until ready to be transplanted into open field.