The key difference between quiescence and dormancy is that quiescence is the inability of a normal, non-dormant seed to germinate because of the absence of conditions suitable for germination while dormancy is an evolutionary adaptation that prevents seeds from germinating during unsuitable ecological conditions that would typically lead to a low probability of seedling survival.
Quiescence and dormancy are two processes related to seeds and their germination. Seed quiescence is the state that delays the germination of seeds due to the absence of conditions required for germination. In fact, it is the inability of normal non-dormant seeds to germinate. It is a kind of resting condition of the embryo. Seed dormancy, on the other hand, is an adaptation of seeds to prevent seed germination under unfavourable conditions to protect seedling from dying. Seeds of fast plants generally undergo quiescence. They do not undergo dormancy.
CONTENTS
1. Overview and Key Difference
2. What is Quiescence
3. What is Dormancy
4. Similarities Between Quiescence and Dormancy
5. Side by Side Comparison – Quiescence vs Dormancy in Tabular Form
6. Summary
What is Quiescence?
Quiescence is a kind of resting stage in normal or non-dormant seeds. It is a process that delays seed germination due to the absence of suitable conditions such as adequate moisture, temperature, etc. for the seed germination. Seed quiescence is a result of factors of the seed itself. Moreover, external factors can affect quiescence. The rate of cell division is repressed during quiescence. Hence, quiescence can also be defined as a condition of repressed cell division. However, the growth of the embryo can resume under favourable conditions, at any time.
Figure 01: Seed Germination
Quiescence can also be considered as a short period of dormancy. But, unlike dormancy, quiescence is reversible upon the return of suitable conditions. Quiescence is important since, in some environments, the environmental conditions are intermittent and unpredictable.
What is Dormancy?
Dormancy is an evolutionary adaptation that optimizes germination under favourable conditions. In other words, seed dormancy is a process that prevents seed germination under unsuitable ecological conditions. It is the inability of a viable seed to germinate. In the dormancy period, the seed remains in the inactive state (arrested development and metabolic depression). Therefore, dormancy safeguards seeds and seedlings from suffering damage or death. This process differs widely among different plant species, in their intensity and duration. However, many plants have seeds that are dormant for months or years. Dormancy can be exogenous dormancy (due to conditions outside the embryo) or endogenous dormancy (due to the conditions within the embryo itself).
Figure 02: Dormancy
Seeds break dormancy naturally when they meet an appropriate environment, including moisture and temperature. Moreover, seed dormancy can be overcome artificially by employing different treatments.
What are the Similarities Between Quiescence and Dormancy?
- Quiescence and dormancy are two forms of delayed seed germination.
- Both quiescence and dormancy prevent seed germination during the unfavourable conditions.
- They increase the probability of seedling survival.
- These processes allow seeds to overcome unfavourable conditions for seedling establishment.
- Both processes are important for plant ecology and agriculture.
What is the Difference Between Quiescence and Dormancy?
Quiescence is a kind of resting stage in normal or non-dormant seeds, which delays the seed germination due to the absence of suitable conditions such as adequate moisture, temperature, etc., for the seed germination. On the other hand, dormancy is an evolutionary adaptation that prevents seed germination under unsuitable ecological conditions. So, this is the key difference between quiescence and dormancy.
Moreover, quiescence is a process that extends for a relatively short time period while dormancy can extend up to a few months to years. Thus, this is another difference between quiescence and dormancy. Besides, seeds of fast plants undergo quiescence. They do not undergo dormant.
Summary – Quiescence vs Dormancy
Both quiescence and dormancy are processes that result in delayed seed germination. Quiescence can be defined as a condition of repressed cell division in which the seed germination is delayed due to the absence of suitable conditions such as adequate moisture, temperature, etc., for the seed germination. On the other hand, dormancy is an evolutionary adaptation that prevents seed germination under unsuitable ecological conditions. So, this is a summary of the difference between quiescence and dormancy.
Reference:
1. Considine, et al. “On the Language and Physiology of Dormancy and Quiescence in Plants.” OUP Academic, Oxford University Press, 6 Apr. 2016, Available here.
2. Bentsink, Leónie, and Maarten Koornneef. “Seed Dormancy and Germination.” The Arabidopsis Book, American Society of Plant Biologists, 2008, Available here.
Image Courtesy:
1. “3989959” (CC0) via Pixabay
2. “Orchids dormancy type1” By Qniemiec – Own work (CC BY-SA 3.0) via Commons Wikimedia