Profile
Settings
Refer your friends
Sign out
True dormancy, also known as intrinsic dormancy, is produced by internal seed characteristics that prohibit germination under normal conditions. Exogenous and endogenous seed dormancy are two common classifications for seed dormancy, based on which component of the seed induces hibernation. Physical, physiological, and morphological dormancy are the three types of dormancy based on their manner of action.
Factors outside the embryo impose this sort of dormancy.
The tissues surrounding the embryo can influence germination by inhibiting water uptake, providing mechanical resistance to embryo expansion and Exogenous dormancy involves radicle emergence, changing gaseous exchange (limiting oxygen to the embryo), preventing inhibitor leaching from the embryo, and providing inhibitor to the embryo. Here are three different types:
Physical dormancy (seed coat dormancy): Dormancy caused by an impenetrable seed coat is known as physical dormancy. The impermeable layer(s) that form during seed or fruit maturity and drying produce physical dormancy.
During dehydration and ripening, the seed coat or seed coating may become stiff, fibrous, or mucilaginous (adhesives gum), making it impermeable to water and gases, preventing the physiological processes that initiate germination. This type of dormancy is frequent in drupe fruits such as olives, peaches, plums, apricots, cherries, walnuts and pecan nuts (hardened endocarp) (surrounding shell). The exterior seed coat hardens and becomes suberized and impermeable to water in several plant groups, such as Leguminosae.
Mechanical dormancy: When seed coats or other coverings are too rigid to allow the embryo to expand during germination, mechanical dormancy occurs. Previously, this method of dormancy was ascribed to several species, however, endogenous components were discovered to be responsible for their hibernation. Low embryo development potential is one of these endogenous causes.
In some fruits, seed coating prevents radicle production, resulting in seed dormancy. Some seed covering materials are too robust to allow the latent embryo to develop during germination, such as walnut shells, stone fruit pits, and olive stones. The water may be absorbed, but the problem, as in walnut, is in the cementing substance. The seed coverings must be relaxed either by establishing wet and warm conditions during storage or by microbial activity before germination can begin.
Chemical dormancy: Growth regulators and other substances found in the embryo’s coverings are included. They can be washed or soaked out of the seed’s tissues, or they can be deactivated in various ways. Rainwater or snowmelt removes other compounds that hinder seeds from germinating.
Chemicals contained in the seeds of various fruits build in the fruit and seed covering tissues throughout development and remain with the seed after harvest. Citrus, cucurbits, stone fruits, pear, grapes, and tomatoes are examples of fleshy fruits with seeds that remain in the liquid. Various phenols, coumarin, and abscisic acid are among the chemicals linked to inhibition. Seed germination can be severely hampered by these chemicals.
Exogenous Dormancy Example
Exogenous dormancy occurs when moisture cannot penetrate the seed, preventing it from germinating. Chemical changes within the seed’s embryo cause endogenous dormancy.
When an embryo is not fully grown, this is an example of endogenous dormancy. Endogenous chemical inhibitors may be to blame.
Exogenous Dormancy Definition
Exogenous dormancy is caused by unfavourable conditions outside the embryo of the seed.
Exogenous dormancy is caused by events outside the embryo.
Conclusion
It entails remaining inactive for a short period, as we all know that all living things require a favourable atmosphere to flourish. Plants, on the other hand, are exposed to a wide range of temperatures and conditions throughout the year. Plants do not have the luxury of movement or physical insulation that animals enjoy.
Living organisms go into dormancy when they don’t grow or develop. They slow or cease their metabolic activity for a short period. It’s also plausible to argue that when live creatures aren’t actively expanding, they go into a deep slumber. Plants are unable to protect themselves or survive in the absence of water, as we all know. As a result, they go dormant to avoid unfavourable climatic and temperature changes. On this page, we will go over all there is to know about Dormancy. Continue reading to learn more.
