Micropropagation seems to be the most promising method for large-scale production of
Alstroemeria plantlets for pot plant production. Flowering of Alstroemeria is induced by cold
treatments and if this can be an integrated part of the micropropagation process an efficient
method for flower induction can be developed. To investigate flower induction, four temperature
regimes (5, 10, 15 and 20°C for 6 weeks) and three methods of reproduction (by seeds, rhizome
division and micropropagation) were tested in nine genotypes. For micropropagated plants,
temperature treatments were performed during root formation in vitro. Seedlings and rhizome
divided plants were given the temperature treatment as established plantlets in 9 cm pots. For all
reproduction methods flower induction was possible at temperatures of 15°C or below. No
substantial differences in the percent of flowering plants were observed between the reproduction
methods. Genotypes reacted differently with respect to effective temperature ranges. In general,
plants treated at 10°C flowered faster, had the lowest number of aborted buds, the shortest
flowering stems, and the highest percentage of reproductive stems as compared to those treated at
other temperatures. The time from end of temperature treatment to flowering was longer for
micropropagated plants than for the other plant types. This delay is probably not due to the in vitro
culture per se, but to differences in plantlet size during the cold treatment. In a second experiment,
root formation during in vitro culture was improved, resulting in a reduced time to flowering of
the micropropagated plants. Reproductive stems were thicker than the vegetative stems and the
diameter of emerging stems increased during ex vitro growth.