SEED DORMANCY

Monday, March 14, 2011

A seed also needs to be able to recognize when the time is suitable to begin growing. With some seeds, this means continuous monitoring until certain temperatures or light levels are registered as registered as acceptable for germination. The chemical computer in a seed is also sensitive to moisture levels and the composition of gases in the soil. By giving each factor its own level of importance the seed can compromise where necessary.

Most seeds have a built-in period of dormancy, up to several years for some species. The shortest time is reserved for those seeds which have evolved in climates that remain constant throughout the year such as tropical areas or for seed produced early in the season when the seed will have all summer to become established. The downy seeds of willow blow along the river in early summer with a good chance of taking hold even though they have a life-span of only one week. Angelica seeds also germinate best when they have just ripened and only a few will maintain their viability over the winter.