Effect of seed material preparation on plant emergence and yield of milk thistle (Silybum marianum (L.) Gaertn.) in a moderate climate

In moderate climates where milk thistle is grown as a medicinal plant it emerges slowly and unevenly and thus it is exposed to weed infestation. The aim of this study was to estimate if the storage temperature and thousand seed weight (TSW) of the seed material have an effect on the number of emerging plants. In the 3-year field experiment, seed material that had been stored at 23, 15 and 7°C and separated according to TSW: 26–30, 20–22 and 20–30 g (control) was used. The emergence of plants was evaluated 4 times, from the BBCH growth stage 09–12 to 18–19/37–38. Storage of seed material at 23 and 7°C resulted in an increase in the number of emerging plants in comparison with seed material stored at 15°C. These differences were evident only at the first time of measurements and gradually reduced as growth progressed. A significantly higher number of plants per 1 m² was obtained from seed material with TSW 26–30 g as compared with the seed material with TSW 20–22 g. These differences continued at all measurement dates but only in one dry year they did have a positive effect on the achene yield.