Dormancy, germination patterns and seedling vigour of fresh and aged seeds of different biotypes of proso millet, Panicum miliaceum L.

In Canada, more than ten biotypes of proso millet exist as weeds ranging from a noxious weed bearing small strongly dormant black seeds to crop escapes with large white or golden seeds and little or no dormancy. Our purpose was to compare dormancy, viability and seedling vigour from fresh seeds with those of the same populations stored for 15 years at 5degreesC and 40%, relative humidity. In a greenhouse study, seedling emergence from aged seeds of the most weedy biotypes (black, dark red), planted 1 and 3 cm deep, was faster and more complete than from fresh seeds, showing that seeds of these biotypes lost dormancy but not viability during storage, Aged and fresh seeds of the crown and white biotypes (crop-like weeds) emerged equally quickly and with no loss of viability during storage. In contrast, aged seeds of crop biotypes had 70% viability or less. Seeds sown on the soil surface had the most variable seedling emergence patterns, Fresh and aged seeds of the crown biotype had rapid, complete emergence. In contrast, the black biotype had slow and intermittent emergence reaching 77% for aged seeds and 28% for fresh seeds after three months, In a different study, emerged seedlings from aged crop seeds had up to 70% mortality before flowering. Seedling mortality from five weed biotypes was negligible.