Abstract
Shoot apices of chrysanthemum cultivar“Kiyomizu, ” which had been given short day induction of 0 to 15 days, were explanted on an agar medium containing HELLER′S or other solutions with auxin, cytokinin or gibberellin. Auxins promoted rooting of explants at doses of 0.2, 2 and 10ppm. IAA was most effective, followed by NAA and 2, 4-D in a decreasing order. The higher the agar concentration within the range from 0 to 1%, the better was the root growth, and the worse the shoot growth. Although the apices excised after 0-10 short day treatments did not initiate flower primordia even when IAA was added. IAA did promote flower bud development when it was given to explants which had excised after 11 to 15 short days treatment. These flower bud reached only the involucre stage and remained at the same stage for at last 30 days. If these buds in the involucre stage were again explanted on a medium containing either IAA, kinetin or gibberellin, or their combinations, some of them developed complete stamen. Complete pistils and elongated petals were particularly noted when gibberellin was added to the medium. If the buds in the involucre stage were explanted on a medium without these growth regulators, they reached the early stage of petal formation.
