Micropropagation of Eucalyptus tereticornis Smith.

Abstract

Axillary shoot bud multiplication has been achieved in Eucalyptus tereticornis Smith. using explants from different regions of 8–10 years old elite trees, growing in the field. Results showed that addition of NAA at 0.1 mgl^-1 and BAP at 1.0 mgl^-1 to modified MS medium induced maximum number of shoot buds. For inducing axial growth in regenerated bud promordia, the hormone concentration of the medium was lowered. The addition of charcoal and gibberellic acid to the medium were beneficial. Rooting was best in Knop's medium containing 1.0 mgl^-1 IBA. The key factor in root induction was primarily a dark incubation for a short period. The percentage of both rooting of shoots and survival of the rooted shoots was 60–80.

Continuous trials using explants from the elite trees throughout the year showed that the period between July–September was the best season for the explant source for rapid and increased multiplication of axillary buds. Phenolic exudation was also minimum at this period. The experiments were repeated using 50 populations from different plantations. It was observed that during culture, genotypically different populations responded differently in spite of optimal growth conditions.