The Relationship between Seed Fertility and Style Shortening after Pollination in Chrysanthemum

Abstract

Experiments were carried out to determin the relationship between the style shortening observed shortly after pollination and the seed fertility (percent of fertile seeds to the total number of disc florets on each flower head). 1. It was found that the morphological difference existed between shortened style and unshortened style observed shortly after pollination was maintained until the seed maturation. 2. Where times of pollination were varied, both percentage of disc florets with shortened style to the total number of disc florets on each flower head and seed fertility increased with increased time of pollination. Moreover, in the disc florets without the shortened style, no seed was harvested. 3. In the case where self- and cross-pollination were made throughout the whle flowering period, it was observed that the percentage of disc florets with shortened style on each flower head and the seed fertility showed the various values, and the relationship between them was highly and positively correlated. Therefore, it was suggested that crossing for seed production could be done rapidly by observing whether the style shortened or otherwise after pollination. 4. To determine the status of the style shortening in the natural condition, observation on disc florets on each of flower head after open-pollination was carried out. In this case also, the relation between the paercentage of disc florets with shortened style to the total number of disc florets on each flower head and seed fertility was highly and positively correlated. This confirmed that the style shortening observed shortly after compatible pollination was the general phenomenon in the disc floret of chrysanthemum.