MICROPROPAGATION OF CHOCOLATE COSMOS (COSMOS ATROSANGUINEUS) BY REPEATED DIVISION OF NODES/AXILLARY SHOOTS AND ADVENTITIOUS SHOOTS FROM MICROSHOOTS

Micropropagation of chocolate cosmos was achieved by subculturing stem section with nodes or dividing axillary shoots on MS (Murashige and Skoog, 1962)-based medium with benzyladenine (BA). The optimal multiplication rate of 3.7 per 17- day culture period was achieved without vitrification on medium containing 0.88 μM BA. Shoots elongated from in vitro cultured microcuttings rooted (60%) on medium with 4.9μM indole-3-butyric acid (IBA). Most plantlets (93%) were acclimatized ex vitro. For the second experiment, plant regeneration from the cultured tissue was attempted. Stem, internode, leaf or petiole with leaf was cut into sections and cultured on the medium with 0, 0.19 or 1.9 μM α-naphtaleneacetic acid (NAA) combined with 4.4 or 18μM benzyladenin (BA). The highest regeneration rate (80%) and shoot number (5.3) per internode section were obtained on the medium with 4.4 μM BA alone. Supplement with 1.9 μM NAA completely suppressed shoot regeneration regardless of BA concentration.