Intraspecific Variation in Sonchus Oleraceus, a Biennial Weed Species, Inside and Outside of Tea Gardens

Although the soil and litter of tea trees in tea gardens contain catechins and caffeine, which are known to suppress plant seed germination, various weed species are still able to grow in tea gardens. Sonchus oleraceus is one of the common weed species in tea gardens. In the present study, we compared the germination characteristics of S. oleraceus seeds from a tea garden population and those from seeds of a population outside of the tea garden. The results indicated that the seeds from the tea garden population possess resistance to catechins and caffeine, and they had a higher germination rate than seeds from outside the tea garden in conditions with high concentrations of catechins and caffeine. In addition, the seeds from the tea garden population were able to germinate throughout the season in order to adapt to disturbances owing to tea garden management, although in their natural life history, the seeds of S. oleraceus break dormancy and emerge from summer to autumn.

Keywords: tea garden, intraspecific variation, Sonchus oleraceus, catechin, caffeine