Author : Seewapong Chamratpan

Summary : This study was conducted to determine the effect of hormones and the optimum condition for the shoot multiplication of explants, rooting, and greenhouse establishment of Aloe barbadensis, and to study the morphogenesis and cytology of plantlets derived from tissue culture. Shoot multiplication was successfully obtained by using shoot tip and stem segments, respectively. Among two kinds of cytokinins, BA was more effective than kinetin in inducing shoot proliferation. On the other hand, kinetin was more effective than BA for inducing callus formation. On the other hand, NAA was more effective than 2,4-D for callus formation, shoot formation, shoot length, root formation and root length. Addition of 15 percent coconut water was satisfactory for root formation in shoot tip explants aand for root formation and root elongation in stem explants. The cytokinin BA at 1.0 ppm and auxin NAA at 0.5 ppm was found to be the most effective for shoot multiplication in shoot tip explants. On the other hand, 1.0 ppm Ba plus 0.25 ppm 2,4-D and 15 percent coconut water was the most suitable for shoot multiplication in stem explants. Shoots were regenerated in shoot tip and stem callus in medium with 0.5 ppm 2,4-D. Shoot bud primordia occurred as globoidal structure on callus surface and protruded in club-shape with concave surface, convex and then scale bud and first leaf occurred, respectively. Regenerated shoots were vitrified and grew slowly. Shoot multiplication was achieved by enhanced axillary bud development. Rooting of plantlets generally occurred. Rooting directly in soil by dipping shoots in 50 ppm NAA and planting in mixed sand, soil and rice hull showed the highest root number and more vigorous roots than shoots rooted in vitro. Plantlets transplanted in mixed sand, soil and rice hull under 94 percent relative humidity showed the highest percent survival of 98.15 percent. Cytological investigation showed the uniform chromosome number of 2N = 14 and the same karyotype of 8 long acrocentric.