BIOL 115 Lecture Notes - Lecture 16: Meristem, Seed Dormancy, Epicotyl
25 Jun 2016
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Document Summary
Seed germination: qualitative change, seeds are generally dormant just after being shed. They won"t germinate even if temperature, soil and moisture conditions are optimal. This is seed dormancy: hormonal seed dormancy - seed dormancy is most frequently due to the presence of the hormone abscisic acid (aba). Aba has to degrade or leach out before the seed will germinate: mechanical seed dormancy - sometimes seed dormancy is due to the seed coat being mechanically too strong. The seed coat has to be cracked by freeze-thaw cycles in nature or weakened by micro- organisms: small wild seeds frequently need a light signal to make them germinate. Because the small seeds have only a small amount of stored food, they have to germinate close to the soil surface. If they see the light, they think they are close to the soil surface.
