Stages of Bean Seed Germination

Dormant Embryo

• The individual dried bean is the mature seed of the bean plant in its quiescent or metabolically inactive state. Inside that seed, protected by a thin but tough seed coat, is everything required to grow a new bean plant, and an entirely new generation of bean pods and seeds. The dormant plant embryo, already fully formed within a dried bean, is encased in concentrated food energy it will need for initial growth.

Water Absorption

• Assuming temperatures are warm enough, when the dried bean imbibes or takes in water it quickly ends dormancy. As the seed hydrates and water plumps up its cells, metabolism begins, helped along by enzymes and rapidly repaired mitochondria. The process of respiration, which provides the embryo with the energy it needs for growth, can begin within minutes of initial water absorption.

Protein Synthesis

• While the seed is still absorbing water, it also rapidly begins to synthesize protein. Early in the germination process the seed's stored messenger ribonucleic acids, or mRNAs, direct protein synthesis, but during later germination new messengers take over, laying down codes for different proteins.

Root Emergence

• When cells in the embryonic root, known as the radicle, elongate due to building cell water pressure, the radicle emerges from the seed--breaking through the tough seed coat. After the radicle emerges, cell division and deoxyribonucleic acid or DNA replication begin and the root grows. Energy reserves stored in the seed--carbohydrates, oil and protein--support both root growth and stem emergence, but all development after the initial emergence of the radicle is considered post-germination seedling growth.