germination

/ jûr′mə-nā′shən /

1. The beginning of growth, as of a seed, spore, or bud. The germination of most seeds and spores occurs in response to warmth and water.

A Closer Look

Dormant seeds are very dry and require the absorption of water to initiate the metabolic processes of respiration and begin to digest their stored food. Respiration requires the presence of oxygen, which must be sufficiently available in the soil for germination to proceed, so the soil must be wet but not so waterlogged as to make oxygen inaccessible. Temperatures must be above freezing (zero degrees Celsius) but not excessively hot (not more than about 45 degrees Celsius). If conditions are right, a radicle (an embryonic root) emerges from the seed coat, anchoring the seed; it then grows and puts out lateral roots. In most eudicots, a part of the developing stem, either the epicotyl (the stem above the cotyledons) or the hypocotyl (the stem below the cotyledons) elongates, forming a hook and gradually pulling the seed coat and the delicate shoot tip above the soil surface. Germination of eudicot seeds is normally divided into two types, designated epigeous and hypogeous. In epigeous germination, the cotyledons emerge above the soil surface, and wither and drop off after their food stores have been used up; in hypogeous germination, the cotyledons remain below the surface and decompose after their food stores have been used up. In most monocots, food is stored in the seed's endosperm (rather than the cotyledon), and it is the single tubular cotyledon that elongates and draws the seed coat out of the soil. The cotyledon conducts photosynthesis, making more food, while the shoot grows up inside the tube.

Example Sentences

The seeds of some chaparral plants need to be treated with heat or liquid smoke to simulate the fire conditions that would naturally trigger germination.

From Los Angeles Times

This "staggered" germination was the plant's way to ensure survival over the long haul.

From Science Daily

Kids get a firsthand look at plant science, from seed germination to the wonders of pollination.

From Seattle Times

"Around 14 days after germination, we unrolled the paper so that we could observe the early development of the roots without the interference of any soil adhered to them," says Hochholdinger.

From Science Daily

This research provides valuable information about how plants reproduce and has the potential to benefit agricultural breeding by increasing seed production and improving germination rates.

From Science Daily

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