Physiological and biochemical parameters influencing ex vitro establishment of the in vitro regenerants of Albizia lebbeck (L.) Benth.: an important soil reclaiming plantation tree

摘要

Present approach demonstrates a speedy and competent in vitro regeneration method for A. lebbeck. The hypocotyl explants (HP) excised from a 15-day-old seedlings were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations (0.5, 2.5, 5.0, 7.5, 10.0 and 12.5 μM) of 6-Benzyladenine (BA), Kinetin (Kn) and 2-Isopentenyl adenine (2-iP) singly as well as in combination with α-naphthalene acetic acid (NAA) or Indole-3-butyric acid (IBA) or Indole-3-acetic acid (IAA; 0.1, 0.5, 1.0, 1.5 and 2.0 μM). The best shoot regeneration rate (88 %) with number of shoots (34.00 ± 1.15) and shoot length (6.30 ± 0.05 cm) per explant was obtained on MS + BA (7.5 μM) + NAA (0.5 μM) after 8 weeks of culture. While, the explants cultured onto the MS + TDZ (Thidiazuron; 0.5, 1.0, 2.5, 5.0 and 7.5 μM) singly showed maximum shoot proliferation response of 77 % when, TDZ exposed cultures were transferred on the BA (7.5 µM) + NAA (0.5 µM) supplied MS medium producing maximum no. of shoots (20.30 ± 0.32) and shoot length (5.15 ± 0.08 cm) after 8 weeks of culture. The regenerated shoots were rooted by using ex vitro rooting method and successfully acclimatized by using a simple acclimatization procedure of 70 days, primarily in soilrite for 28 days and finally in soilrite + garden soil (1:1) for 70 days under culture room conditions (150 PPFD). This acclimatization period under the optimized conditions of culture room ensures a high survival rate (80 %) of the plantlets in the field conditions. Photosynthetic pigments (Chlorophyll a, b and carotenoid content) evaluated during acclimatization period showed a decreasing trend in the initial 14 days afterwards a significant increase in the subsequent period of 21–70 days. While all the stress parameters MDA and H2O2 content showed decreasing trend all through the acclimatization, concurrently all the tested antioxidative enzymes (SOD, CAT, APX and GR) exhibited an increasing trend.