Effect of colour and size grading of China aster (Callistephus chinensis Nees) seeds on their germination

Seeds of 3 commercial China aster (Callistephus chinensis Nees) lots were divided by hand into 3 grades with different colours: dark brown, brown and light brown, and 2 grades with a different size: length below 3.9 mm (small) and above 3.9 mm (large). The colour grading was done based on the Royal Horticultural Society Colour Chart and size grading was done by hand for each seed. Then, seeds were routinely germinated based on the International Seed Testing Association (ISTA) rules. The size of seeds had no effect on their germination. The dark brown seeds germinated better than the light brown ones. Removing light brown seeds from the China aster seed lot improved their germination.