Germination is the process by which a plant grows from a seed or spore. It is the process of reactivation of metabolic machinery of the seed resulting in the emergence of radicle and plumule. When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. The embryo’s cells start to enlarge. Then, the seed coat breaks open and the root emerges first, followed by the shoot that contains the leaves and stem. The complete process of seed germination is carried out in the following steps:
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Imbibition: During the beginning stage of germination, the seeds take up water rapidly and this results in swelling and softening of the seed coat at an optimum temperature. This stage is referred to as Imbibition. It starts the growth process by activation of enzymes.
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Activation of enzymes: The seed activates its internal physiology and starts to respire and produce proteins and metabolizes the stored food. This is a lag phase of seed germination.
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Emergence of radicle and plumule: The radicle is the embryonic root, and the plumule is the embryonic shoot. The radicle emerges first, followed by the plumule.
Seeds remain dormant until conditions are favorable for germination. All seeds need water, oxygen, and optimal temperature to germinate. Sunlight supports the germination process by warming the soil. Although uncommon, some seeds need direct contact with sunlight to germinate. Once leaves have sprouted, sunlight is the primary energy source for plant growth through the process of photosynthesis.
