* VEGETATIVE PROPAGATION OF ALSTROEMERIA HYBRIDS IN VITRO

Abstract

Terminal and lateral tips from fleshy rhizomes of Alstroemeria hybrids were isolated in vitro and induced to form a new rhizome. The cultivar Toledo was used in most experiments, but later other cultivars were also tested. The basic culture medium for rhizome isolation and for rhizome multiplication was: Murashige and Skoog (MS) macro- and micro-salts at full strength (except Fe), NaFeEDTA 25 mg/l, saccharose 3°BA 2–4 mg/l vitamin B1 0.4 mg/l, and Difco Bacto-agar 0.7 EThe basic culture medium for rooting was slightly different: saccharose 5°BA was omitted and 0.5 mg/l NAA was added. Rhizome cultures were placed at 21°C and 8 h fluorescent light/16 h darkness. Rooting was carried out at 21°C and 16 h fluorescent light/8 h darkness. Rhizome multiplication required a cytokinin in the medium; BA and PBA were most effective, whereas kinetin, 2iP, and zeatin were not very effective. BA at 2–4 mg/l partially suppressed erect shoot growth and stimulated rhizome branching. Addition of auxin had no effect on rhizome multiplication. Relative small rhizome explants (with one bud) had a higher multiplication rate than large ones. Optimal rhizome multiplication required 3 week cycles of subculturing; cycles of 4, 5 and 6 weeks being less productive. The multiplication rate was increased by growing the rhizomes in liquid media; however, this resulted in vitrification. Excised rhizome explants can be rooted by subculturing rhizome explants on cytokinin-free media containing auxin. Generally NAA (optimum 0.5 mg/l) induced better rooting than IBA. In vitro rooted plants were successfully transferred to the greenhouse and developed into normal flowering plants.