Mass multiplication of Bixa orellana L. through tissue culture for commercial propagation

To reduce the time period for in vitro regeneration in annatto (Bixa orellana L.), a highly efficient two-stage plant regeneration protocol had been developed that can be used commercially. Different types of explants: nodal shoot tips, shoot tips and single nodes from in vitro grown seedlings were inoculated onto the Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of plant growth regulators. Highest number of shoot buds was obtained when nodal shoot tip explants were inoculated onto MS medium supplemented with 31.1 μM N⁶-benzyladenine (BA) and 14.7 μM phenylacetic acid (PAA). PAA in combination with BA exhibited a synergistic effect on shoot multiplication and elongation. Sub-culturing of the shoots onto the MS medium supplemented with BA (13.3 μM) and PAA (7.3 μM) produced elongated shoots. Elongated shoots when inoculated onto the MS medium supplemented with 4.9 μM indole-3-butyric acid (IBA) produced optimal rooting. The rooted plantlets were hardened and their field survival rate after 6 weeks time was 73%.