Micropropagation of Adult and Juvenile Neem (Azadirachta indica A. Juss)

The influence of tree age and phytohormones (cytokinins and auxins) on micropropagation of Neem (Azadirachta indica A. Juss) was investigated using nodal segments from mature (15-year-old) trees and green-house-grown juvenile (1.5-year-old) seedlings. Modified MS medium (MS-RMN) supplemented with a combination of 2.0 mg/l 6-Benzylaminopurine (BA) and 0.3 mg/l indole-3 butyric acid (IBA) was effective in shoot bud sprouting in both juvenile and mature trees. Maximum multiple shoots were induced on modified MS medium supplemented with 1 mg/l BA + 0.5 mg/l 1-naphthalene acetic acid (NAA). The highest frequency of rooting was observed in half-strength MS medium supplemented with 2.0 mg/l IBA. Culturing of elongated shoots in basal MS medium for 2 weeks before subculturing in rooting medium proved beneficial. The influence of age of explant source was not observed in rooting stage. Overall, the cultures established from the explants collected from the juvenile seedlings were superior to those from mature trees. Maintenance of high humidity during hardening of micropropagated plantlets was found to be essential. The vermiculite was the best (72%) potting mixture for survival of plantlets during hardening.