Double dormancy

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 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?

Several major factors 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, the seed does not germinate even under the most favourable conditions.

Double Dormancy

You won’t see any green growth from peony or trillium seeds planted in the fall until the second spring if you’re lucky if you plant them in the fall. Typically, this is referred to as an example of double dormancy because the seed requires two periods of cold before it will germinate. Double dormancy is a term used to describe the fact that two stratifications (cold) periods are required to overcome two dormancy.

It is undeniable that there is a second dormancy period for germination. There are many different types of seeds that have complicated dormancy that must be overcome before germination can take place. Many other seeds have a straightforward dormancy and germinate with relative ease.

Between these two extremes, there are a plethora of other seeds that may or may not exhibit double dormancy, depending on how one defines germination in this context. According to the definition of germination as the appearance of a root or shoot, many seeds that are labelled as being double dormant are, in fact, not double dormant at all.

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 the 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.