EFFECT OF SEED HARVESTING SEASON AND STERILIZATION TREATMENTS ON GERMINATION AND IN VITRO PROPAGATION OF Albizia lebbeck (L

This study was undertaken with the objective of standardizing the protocol for the micropropagation of Albizia lebbeck (L.). Seeds were collected from three different colored pods (yellow, dark yellow and brownish yellow) harvested from field grown Albizia tree from November to January and were surface sterilized using different concentration of mercuric chloride (0.050.15 % w/v) for different exposure durations (2, 5 and 8 min). Seeds collected from dark-yellow colored pod showed the highest germination (83.3 %) and short germination time (4.29 days), while those collected from brownish yellow colored pod showed relatively less germination (53.3%) and longer germination time (6.0 days). Success of seed germination increased with maturity up to a certain level after which it declines significantly with increasing harvesting time. A five-minute dip of HgCl2 (0.1%) was found to be the optimum duration for giving the maximum (83.3%) germinated and healthy seedlings. Increasing time and concentration of HgCl2 significantly reduced the contamination, but on the other hand it also effected the germination of seeds. Best shoot regeneration response from in vitro nodal segment was obtained on MS medium supplemented with BAP (2.0 mg/l) + NAA (0.5 mg/l). The highest percentage of callus induction (85%) was also observed in the above same media from in vitro internodal segment. Proliferated micro-shoots showed 60% rooting on half strength medium supplemented with IAA (2.0 mg/l) after 4 weeks of culturing. The well rooted micropropagated plantlets were acclimatized and successfully established in pots containing sterilized soil and sand mixture (1:1) with 60% survival rate under field conditions.