Floral Pigmentation in Gibberellin-treated Tulips

Pigmentation in the perianths of GA₃-trcated tulips was studiedspectrophotometrically and colorimetrically. Anthocyanin pigmentationin the perianth was enhanced by treatment with 300 and 400 ppmGA, I ml per plant, in the form of drops applied to the apicalmeristem still enclosed by whorled undeveloped foliage. Rapidanthocyanin pigmentation accompanied by the disappearance ofchlorophylls in the perianth commenced in the following order:perianth of plants receiving 2, 5, 8 °C treatments for onemonth each with two GA applications followed by those receiving2, 5, 8 °C with one GA application and finally those receiving2, 5, 8 °C without GA. By treating with GA dissolved inmethanol, anthocyanins appeared on the perianth tip first. Inthe case of GA in ethanol application, however, the anthocyaninpigmentation occurred from the upper half of the perianth.