Dormancy is a stage in an organism’s life cycle during which growth, development, and (in the case of animals) physical activity are temporarily slowed or suspended. This reduces metabolic activity and, as a result, aids an organism in its efforts to conserve energy. Dormancy is often found to be closely associated with specific environmental conditions, such as temperature. Through predictive or consequential mechanisms, organisms can time their entry into a dormant phase with the rest of their environment. When an organism enters a dormant phase before the onset of adverse conditions, this is referred to as predictive dormancy. Many plants, for example, use changes in photoperiod and temperature to predict the onset of winter, and they are not alone. When organisms enter a dormant phase as a result of adverse environmental conditions, this is referred to as consequential dormancy. This is a common occurrence in areas where the weather is unpredictable. When environmental conditions change rapidly, animals reliant on consequential dormancy may die in large numbers. However, the use of consequential dormancy can be advantageous because organisms remain active for a longer period of time and are therefore able to make better use of available resources.
Seed Dormancy
As defined by the International Seed Dormancy Association, seed dormancy is defined as the state or condition in which seeds are prevented from germinating despite the presence of favourable environmental conditions for germination. These conditions include temperature, water, light, gas, seed coats, and other mechanical restrictions.
The primary reason for these conditions is that they require a period of rest before they are capable of germinating successfully. These conditions can last anywhere from a few days to several months or even years. These conditions consist of a combination of light, water, heat, gases, seed coats, and hormone structures, among other things.
What are the Reasons or Causes for the Seed Dormancy?
There are several major factors that contribute to seed dormancy. The following are a few of the possible causes of seed dormancy.
- Light
- Temperature
- Hard Seed Coat
- Period after ripening
- Germination inhibitors
- The seed coat’s resistance to water absorption
- The seed coat’s resistance to oxygen absorption
- Mechanically resistant seed coat
- The presence of solutes with a high concentration
Seed Dormancy Comes in Many Forms
Innate
This inability to germinate in some species may be due to the embryo being immature at the time of dispersal, which in some cases may be the case.
Enforced dormancy
A condition in which seeds are unable to germinate because of environmental constraints such as a lack of sufficient moisture, oxygen, light, or a temperature that is too high for germination.
Induced dormancy
This type of seed dormancy occurs when a seed has ingested water but has been placed in an environment that is extremely unfavourable for germination, such as a dry environment. After all is said and done, seed does not germinate even under the most favourable conditions.
Methods of Breaking Seed Dormancy
The following are the various methods of reversing dormancy that are available:
When the embryo is exposed to an appropriate environment, such as adaptive moisture and temperature, the dormant state is terminated. Many species’ seed coats become permeable as a result of the rupturing of the smoothing action of natural agents such as microorganisms, temperature, and abrasion by the digestive tracts of birds and other animals that consume the seeds. Among the other natural methods are:
Completion of the over-ripening period.
The leaching of inhibitors from the seed coat is a problem.
Inactivation of inhibitors is accomplished through the application of cold, heat, and light.
Production of growth hormones, which can be used to counteract the effects of inhibitors on the body.
Seed Dormancy Can Be Overcome Through Artificial Means
Some of the artificial methods that have been used to break seed dormancy include the following:
Hot water is used to terminate the action of waxes, surface inhibitors, and other substances.
Seed coats are rupturing as a result of filing, chipping, or threshing through machines.
Depending on the type of seed dormancy, exposure to heat, cold, or light may be necessary.
To weaken the tough seed coats, apply hydraulic pressure for 5 to 20 minutes at a time for 5 to 20 minutes.
In order to eliminate any remaining traces of mineral acid from the seed coat, it is treated with concentrated sulphuric acid.
Seeds that have gone dormant are treated with this method.
It is possible to overcome dormancy through a variety of treatments, which are further divided into the following categories:
Treatment of the seed coat
These treatments soften or crack a hard seed coat, making it permeable to water or gases, depending on the method used. Scarification is the term used to describe this process. The treatment can take the form of a chemical or a physical process.
Treatment with high temperatures: Incubation at 40-50 degrees Celsius for a few hours to a few days may be effective in overcoming dormancy in some species. For example, rice seeds are treated with hot water at 40 degrees Celsius for at least 4 hours before planting.
Treatments with chemicals
Irrigated germination growth regulators can be formulated with plant growth regulators or with other chemicals.
The significance of seed dormancy
It comes after the practice of storing seeds for later use by animals and humans.
Because it aids in the dispersal of seeds in an unfavourable environment, it is beneficial.
Plants growing in desert environments benefit greatly from the dormancy induced by inhibitors found in their seed coats.
Allows the seeds to remain in suspended animation without suffering any harm during periods of extreme cold or high summer temperatures, as well as during periods of drought.
Dormancy allows seeds to survive in the soil for several years and to provide a continuous source of new plants, even when all of the mature plants in an area have died as a result of natural disasters. Adaptability and resistance to inappropriate germination are two of the characteristics of seed. However, there is no consistent germination. In addition to making the maintenance of the plant population more difficult, dormancy also interferes with the seed testing procedure.
Conclusion
The term “dormant” refers to a seed that has reached maturity and viability but has not yet germinated under favourable conditions. It is also referred to as embryo dormancy or internal dormancy. It is caused by endogenous characteristics of the embryo that prevent germination from taking place in the seed.