Once scattered or sown Seeds can have a period of dormancy which may vary from days to months and even years. It is also sometimes called the ‘rest or quiescent period’ in plants. Once the seeds have reached maturity, conditions of light, water, oxygen and temperature are favourable and any hard seed casing has been cracked open, germination begins.
Seed germination includes a series of events happening in a sequential order.
Stage 1: Imbibition: This is the first step where the seed rapidly absorbs water from the environment causing the seed coat to swell and become soft.
Stage 2: Activation: The absorbed water activates the enzymes present inside the seed that starts the growth phase in the embryo. The seed begins respiration by absorbing oxygen and utilizing the stored food to form proteins necessary for its growth.
Stage 3: Growth (Formation of Root and Shoot): As the rate of respiration increases, the seed coat ruptures to form a radical which later develops into a primary root, while the plumule develops into a shoot. During this period, the enzymatic activity remains at an all-time high.
Stage 4: Morphogenesis (Formation of Seedling): This is the final step of seed germination when the first embryonic leaf or the cotyledon appears. Gradually, tiny leaves sprout from the shoot ends, these are known as foliage leaves. During this initial phase of development the baby plant continues to use the food stored within the seed. Once this phase is complete, it starts synthesizing its own food by photosynthesis