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Micropropagation, Morphogenesis, and Cytological Study of Aloe (Aloe barbadensis Mill.) in Vitro
Dissertation Abstract:
This study was conducted to determine the effect of hormones on and the optimum condition for 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 obtained by using shoot tip and stem segments.
Between two kinds of cytokinins, 6-benzyladenine (BA) was more effective than kinetin in inducing shoot proliferation. However, kinetin was more effective than BA in inducing callus formation, increased tissue weight, root formation, and root length.
Between the two kinds of auxins, 2,4-D was more suitable than naphthalene acetic acid (NAA) for 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 le ngth.
Adding 15 percent coconut water was satisfactory for root formation in shoot tip explants and for root formation and root elongation in stem explants.
BA at 1.0 ppm and NAA at 0.5 ppm was found to be 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 were the most suitable for shoot multi plication in stem explants.
Shoots were regenerated in shoot tip and stem callus in a 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 fi rst leaf occurred. respectively.
Regenerated shootS were vitrified and grew slowly. Shoot multiplication was achieved by enhanced axillary bud development. Rooting of plant lets 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 transp lanted 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 uni form chromosome number of 2N = 14 and the same karyotype of eight long acrocentric and six small submetacentric chromosomes with relative lengths ranging from 0.034 to 0.106 in mother plants and regenerated plantlets.