During the past two decades, researchers have reported a number of soft pesticide-like materials derived from the neem tree (Azadirachta indica) which seem to protect plants in benign ways. The quality and quantity of these secondary metabolites vary greatly among biotypes of the neem tree. In vitro culture may provide the means to enhance the production of these materials through selection and multiplication of these selected types. We obtained a large number of plantlets through in vitro culture. Apical and axillary shoot buds of young sprouts of coppiced branches of 25-year-old elite trees growing in the village grove, were used as explants. When the explants were culture directly on MS medium with 1.0 mg/l BA+0.1 mg/l NAA, multiple shoot buds were formed. These shoots continued to proliferate through 5 or more subculture with an average of 15 shoots per transfer. For inducing axial growth in regenerated shoots, the concentration of BA and NAA was lowered to 0.5 mg/l and 0.05 mg/l, respectively and CH at 100 mg/l and CM at 10% (v/v) were added. For rooting the well developed shoots were excised from the culture flask and implanted individually on root induction medium. Within 3 weeks of transfer, 100% rooting was achieved in medium consisting of half-strength MS salts with IBA and IAA at 1.0 mg/l each. Young rooted plantlets were transplanted directly from the culture tubes to clay pots containing sterile sand, soil and humus (1:2:1) and covered by polythene bags. Within 34 weeks the plants were large enough for transfer into greenhouse. About 80% of these plants survived.
Key words: Azadirachta indica, propagation, genetic conservation.
Correspondence: Shyamal K. Roy, Department of Botany, Jahangirnagar University, Savar, Dhaka, Bangladesh