| Abstract: | Somatic embryos regenerated in high-frequency (up to 100 %) on immature cotyledons of Azadirachta indica at a low concentration of thidiazuron (TDZ; 0.5  M). Regeneration occurred exclusively from abaxial surface. Frequency of regeneration declined with the age of the cotyledons: on semimature cotyledons regeneration occurred only from some regions of the abaxial surface and on mature cotyledons it was confined to corners. However, an increase in concentration of TDZ to 1.0 M improved the regeneration response. Higher regenerative capacity of immature cotyledons was due to presence of milk in immature fruits because regeneration response of immature cotyledons declined on washing of cotyledons for 24 h in liquid medium, and milk from immature fruits augmented the regeneration response of mature cotyledons. Somatic embryos regenerated readily on hormone-free medium and plantlets derived were able to survive after transfer to soil. |
