The germination of seeds is dependent on internal and external conditions. The important external factors include: temperature, water, oxygen and sometimes light or darkness.
Water is required for germination. Mature seeds are extremely dry and need to take in significant amounts of water, relative to the seeds dry weight, before cellular metabolism and growth can resume. Most seeds respond best when there is sufficient water to moisten the seeds but not soak them. The uptake of water by seeds is called imbibition which causes the swelling and the breaking of the seed coat. When seeds are formed, most plants store food, like starch, proteins, or oils, to provide nourishment to the growing embryo inside the seed. When the seed imbibes water, hydrolytic enzymes are activated that break down these stored food resources into metabolically useful chemicals, allowing the cells of the embryo to divide and grow, and then the seedling can emerge from the seed. Once the seedling starts growing and the food reserves are exhausted, it requires a continuous supply of water, nutrients and light for photosynthesis, which provides the energy needed for continued growth.
Water is required for germination. Mature seeds are extremely dry and need to take in significant amounts of water, relative to the seeds dry weight, before cellular metabolism and growth can resume. Most seeds respond best when there is sufficient water to moisten the seeds but not soak them. The uptake of water by seeds is called imbibition which causes the swelling and the breaking of the seed coat. When seeds are formed, most plants store food, like starch, proteins, or oils, to provide nourishment to the growing embryo inside the seed. When the seed imbibes water, hydrolytic enzymes are activated that break down these stored food resources into metabolically useful chemicals, allowing the cells of the embryo to divide and grow, and then the seedling can emerge from the seed. Once the seedling starts growing and the food reserves are exhausted, it requires a continuous supply of water, nutrients and light for photosynthesis, which provides the energy needed for continued growth.
