Effect of Age of Explants on Somatic Embryogenesis and Plant Regeneration in Eucalyptus tereticornis SM

Plant regeneration was achieved via somatic embryogenesis in Eucalyptus tereticornis SM. Callus was induced from cotyledon explants isolated from 7-to-28 day-old seedlings at weekly intervals when cultured on MS basal medium with different concentrations of NAA. The highest frequency of callus induction was noticed on MS medium containing 10.74 uM NAA. The development of somatic embryos was stimulated after transferring the friable nodular callus to MS medium containing different concentrations of BAP. Highest frequency of embryogenesis was observed after transferring the callus into medium containing 2.22 uM BAP. The frequency of callus development and embryogenesis varied according to the concentration of growth regulators and was inversely proportional to the age of the explants. Conversion of plantlets occurred on growth regulator free medium. Somatic embryos were formed directly from 7-days-old cotyledons without any intervening callus phase on MS medium containing 0.88 uM BAP. Fully developed plantlets were transferred to polybags. After hardening, they were transferred to greenhouse and planted in the field.