Thistles of Greece and their potential value as Medicinal Crops: Study on their First Growth

Canadian thistle ( Cirsium arvense (L.) Scop.), Milk thistle ( Silybum marianum (L.) Gaertn.) and Scotch thistle ( Onopordum acanthium L.) are weed species, which can also be useful plants because of their medicinal properties. A preliminary seed germination test was conducted, while a greenhouse experiment was also established during 2015 at the Agricultural University of Athens, where seed germination, seedling emergence, first growth rate and biomass production of three biotypes of S. marianum , two biotypes of C. arvense and three biotypes of O. acanthium were evaluated. According to the results of this study, seed germination and seedling emergence were high for all species and biotypes. First growth rate and earliness were significant different between the several species. High biomass production was found in the biotypes originated from arable fields. In conclusion, this research work proved that there is a potential of exploitation of thistles according to their many uses. Seed germination, seedling emergence, first growth, biomass production and earliness of some biotypes seem rather satisfactory, while the high genetic variability of these three weeds can be used as a source for any future breeding attempts.