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Dormancy should not be confused with seed coat dormancy, external dormancy, or hardheadedness, which is caused by the presence of a hard seed covering or seed coat that prevents water and oxygen from reaching and activating the embryo. It is a physical barrier to germination, not a true form of dormancy (Quinliven, 1971; Quinliven and Nichol ...
Aestivation (Latin: aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. [ 1 ]
Dormancy caused by an impermeable seed coat is known as physical dormancy. Physical dormancy is the result of impermeable layer(s) that develops during maturation and drying of the seed or fruit. [12] This impermeable layer prevents the seed from taking up water or gases. As a result, the seed is prevented from germinating until dormancy is broken.
Photoblasticism is a mechanism of seed dormancy. Photoblastic seeds require light in order to germinate. [2] Once germination starts, the stored nutrients that have accumulated during maturation start to be digested which then supports cell expansion and overall growth. [3]
Thus dormancy is a state of the seed, not of the environment. [34] Induced dormancy, enforced dormancy or seed quiescence occurs when a seed fails to germinate because the external environmental conditions are inappropriate for germination, mostly in response to conditions being too dark or light, too cold or hot, or too dry.
Many seed species have an embryonic dormancy phase and generally will not sprout until this dormancy is broken. [ 1 ] The term stratification can be traced back to at least 1664 in John Evelyn 's Sylva, or A Discourse of Forest-Trees and the Propagation of Timber , [ 2 ] where seeds were layered (stratified) between layers of moist soil and the ...
Sometimes, the expression of dormant genes can be induced by artificial stimulation. Atavisms have been observed in humans, such as with infants born with vestigial tails (called a "coccygeal process", "coccygeal projection", or "caudal appendage"). [8] Atavism can also be seen in humans who possess large teeth, like those of other primates. [9]
After vernalization, plants have acquired the ability to flower, but they may require additional seasonal cues or weeks of growth before they will actually do so. The term is sometimes used to refer to the need of herbal (non-woody) plants for a period of cold dormancy in order to produce new shoots and leaves, [1] but this usage is discouraged ...