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True dormancy or inherent (or innate) dormancy is caused by conditions within the seed that prevent germination even if the conditions are favorable. [7] Imposed dormancy is caused by the external conditions that remain unsuitable for germination [8] Seed dormancy can be divided into two major categories based on what part of the seed produces dormancy: exogenous and endogenous. [9]
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 ...
When ABA levels are higher than GA then that leads to dormant seeds and when GA levels are higher, seeds germinate. [25] The switch between seed dormancy and germination needs to occur at a time when the seed has the best chances of surviving and an important cue that begins the process of seed germination and overall plant growth is light.
Gibberellins cause also seed germination by breaking the seed's dormancy and acting as a chemical messenger. Its hormone binds to a receptor, and calcium activates the protein calmodulin , and the complex binds to DNA, producing an enzyme to stimulate growth in the embryo.
Seeds of many trees, shrubs and perennials require these conditions before germination will ensue. [citation needed] In the wild, seed dormancy is usually overcome by the seed spending time in the ground through a winter period and having its hard seed coat softened by frost and weathering action. By doing so the seed is undergoing a natural ...
Cover the seeds by smoothing the soil back over the top. Water your seeds once more using a very gentle spray so that the soil will settle. (Too hard a spray will dislodge or even wash away the ...
There have been several seeds known at different times as the oldest viable seed. Dormancy allows seeds to survive for extended periods, which can aid in seed dispersal and spread out the growth and establishment of seedlings , increasing the likelihood that some of the next generations survive if conditions are not suitable for seedling ...
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