Abstract
Solanum aculeatissimum (Solanaceae) plants, which were cultivated in the open field, were harvested once a month from June 1985 to January 1986. The growth matter and content of steroid saponins, aculeatiside A and B which are precursors of steroid hormones in root, were then measured in order to examine their seasonal variations during one vegetation period. The aerial parts of the plants died of chill and frost in January. In November the dry weight of root reached the maximum, and the content of steroid saponins was more than 10% and showed a maximum. The yield of steroid saponins per plant was greatest in November. These results suggest that November is the appropriate time for harvest, and that S. aculeatissimum can be more useful than the Dioscorea species which is now used as a source plant of steroid hormones.
