Germination

Germination is the process by which a seed resumes growth after a period of dormancy and develops into a seedling. In most flowering plants, germination begins when a seed takes up water, a phase called imbibition, which reactivates cellular metabolism and activates enzymes that mobilize stored reserves. As growth proceeds, the embryonic root (radicle) usually emerges first, followed by the shoot (plumule).

Germination proceeds through several stages. Imbibition is rapid water uptake, followed by a lag phase in which enzymes are synthesized and energy stores are mobilized. Finally, the radicle breaks through the seed coat and the shoot begins to grow, establishing photosynthesis and nutrient uptake.

Environmental requirements for germination vary by species but generally include adequate moisture, a suitable temperature range, and sufficient oxygen. Light can influence germination in some seeds, with photodormant species requiring light or darkness to trigger germination. The seed coat’s permeability also matters, and some seeds require scarification or stratification to overcome dormancy.

Seed dormancy is an adaptive pause that prevents germination under unfavorable conditions. Dormancy can be physical (hard seed coats), physiological (hormonal inhibition), or morphophysiological (undeveloped embryos). Treatments such as stratification (cold storage), scarification (abrasion or damage to the coat), or after-ripening can help release dormancy and promote germination.

Germination is a key early stage in a plant’s life cycle and a focus of agricultural management. It determines establishment, influences crop yield, and is a common measure of seed vigor and viability in research and seed testing.