Rapeseed is the world's third most important oilseed crop in terms of oil production and the most important in Europe. While spring oilseed rape is most widely grown worldwide, winter oilseed rape predominates in Europe. In the European Union, 5.89 million ha were grown to produce 19.4 million tonnes in 2022 (EUROSTAT 2023). Rapeseed has relatively small seeds with a variable seed weight that is determined by genetics and conditions during production. The thousand seed weight (TSW) of winter oilseed rape varies usually between 4-6 g.Seed size has been studied to effect germination, establishment, early growth and final yield of different crops. According to Guberac et al. (1998), the large seed fraction of oat had the highest germinability, germ length, root length and yield compared to the small seed fraction. Moshatati and Gharineh (2012) found that the grain weight of wheat had a significant effect on the seedling length and dry weight. Three size wheat classes demonstrated that the large seed size resulted in the highest shoot and root length (Shahi et al. 2015).The effect of seed size has been shown in Brassica crops, too. Emergence, dry weight, and final yield increased with increasing seed size in hybrid broccoli cultivars of B. oleracea L. ssp. Italica (Heather and Sieczka 2019). In summer turnip rape cultivars (B. rapa), large seeds had better establishment, higher plant weights and higher seed yield compared to small seeds (Elliott et al. 2007). Rapeseed cultivars (B. napus) seedlings from large seeds improved establishment, shoot weight, biomass and yield compared