In vitro plantlet regeneration from seedling nodal explants of Acacia catechu.

Multiple shoots were initiated after 20 days in stem nodes excised from in vitro grown seedlings of Acacia catechu, on Murashige and Skoog's medium adjuvanted with 1 to 100 microM of N6-benzyladenine (BA). Explants were subcultured on the same medium augmented with 1.5 g l(-1) of polyvinylpyrrolidone (PVP) after 30 days. In the second subculture, after 30 days, the explants were transferred to a medium lacking PVP, but containing 10 microM of BA, where nine or ten shoots differentiated per explant within next 30 days. If individual shoots along with some callus were subcultured on BA (10 microM), nearly 15 shoots per explant regenerated in 90 days. Thus, the average number of shoots obtained from each node was 142 after 180 days. Since a seedling develops four nodes after 20 days, theoretically an average of 568 shoots can be obtained from a single seed. If shoots were individually subcultured on 1/2-strength MS medium with 14.7 microM of indole-3-butyric acid (IBA), roots developed in 20 days. Addition of 40 mg l(-1) of glutamic acid to the rooting medium prevented leaf senescence. These plantlets thrived well in garden soil, sand and silica (1:1:1).