Factors controlling Flowering in the Chrysanthemum

Abstract

By confining low-temperature treatment to the growing tip of the Chrysanthemum plant, the apex has been shown to be the seat of perception of vernalization, a result which is in full accord with earlier experiments on other plants requiring vernalization. Experiments on the translocation of the stimulus through mature tissues involving stock/scion and ‘approach’ grafts with or without defoliation gave negative results. By decapitating in turn the main axis and the resulting laterals produced, it has been shown that the stimulus is passed on from existing apices to laterals of up to the seventh order at least, lateral apices which were formed well after the time of chilling. These results are discussed in relation to prior work on the existence of a specific vernalization substance as well as a flowering hormone and their translocation.