Seed Dormancy: Causes, Types, Methods, Methods and Protocols

Edited By Irshad Anwar | Updated on Jul 02, 2025 07:09 PM IST

Definition Of Seed Dormancy

Seed dormancy is a state in which seeds do not germinate even if placed in suitable environmental conditions. This is, therefore, a key determinant of plant survival, allowing seeds to tolerate unfavourable conditions and germinate only when conditions are more likely to support seedling establishment. Dormancy prevents seeds from sprouting prematurely, under which they have poor survival rates, to align germination with favourable environmental cues in enhancing the possibility of successful plant development.

Types Of Seed Dormancy

The types of seed dormancy are discussed below-

Innate Dormancy

Intrinsic to the seed itself, innate dormancy will not germinate when conditions are favourable because of factors within the seed. It often results from the physiological state of the seed or hard seed coat and is observed in many species, including black locusts. This type of dormancy makes sure that seeds germinate under the most optimal circumstances for survival and reproduction only.

Induced Dormancy

Induced dormancy is a state in which seeds go dormant as an effect of external environmental conditions, usually temperature or the presence of water. In this regard, the dormancy is short-term and may be observed in certain species, such as the tomato—Solanum lycopersicum—that may exhibit dormancy due to stress or unsuitable conditions to prevent untimely germination.

Enforced Dormancy

Enforced dormancy occurs with seed germination forbidding factors, which are usually mechanical or severe environmental. For example, enforced dormancy occurs in the seeds of the fireweed (Epilobium angustifolium) by extreme heat from fires, required to trigger its germination naturally.

Causes Of Seed Dormancy

The causes are described below-

Physical Dormancy

Physical dormancy occurs when the seed coat acts as a physical barrier to water and gas reaching the embryo. Examples include the legume family, including peanuts (Arachis hypogaea), where the impermeable seed coat is the major factor in dormancy. Scarification is one such method for physically altering the seed coat, often employed to overcome this type of dormancy.

Physiological Dormancy

Physiological dormancy is induced by factors in the seed itself, such as hormone imbalance or other stages of development of the seed. Abscisic acid, ABA, and Gibberellins, GA, are the two primary hormones affecting this kind of dormancy. For instance, Lettuce, Lactuca sativa seed, undergoes physiological dormancy that is controlled by the mentioned hormones, through inducing certain environmental factors, breaking the dormancy.

Morphological Dormancy

One of the types of morphological dormancy includes underdeveloped embryos that need further development before germination. For instance, the coconut (Cocos nucifera) requires the embryo to take some time and develop enough in the seed. In most cases, this kind of dormancy calls for certain conditions regarding development to be broken.

Combination Dormancy

Combination dormancy refers to the combination of physical, physiological, and morphological factors that inhibit germination. For example, in the common buckwheat (Fagopyrum esculentum) there may be a hard seed coat with physiological dormancy, and more than one treatment may thus be required to achieve the germination of such seed.

Mechanisms of Overcoming Seed Dormancy

The mechanism is described below-

Scarification

Scarification is a process of mechanically or chemically weakening the seed coat to allow for water absorption. Mechanical scarification includes abrasion and nicking, while chemical scarification involves the action of acids in weakening the seed coat. The practical applications are in agriculture, where scarification improves the germination rate for seeds with hard coats.

Stratification

It's the process of subjecting seeds to cold or warm temperatures to break dormancy by imitation of natural seasonal conditions. Cold stratification, like storing seed lots at low temperatures, is used for species like maple (Acer spp.), while warm stratification refers to the process of exposing the seeds to higher temperatures. Such methods are fundamental in manipulating seed germination in controlled environments.

Light And Temperature Treatments

Light and temperature treatments are such that the exposure of seeds to specific light conditions and temperature ranges triggers germination. In other words, some seeds have to be exposed either to light or to a change in temperature to break dormancy. For instance, practical applications include the use of growth chambers where optimal conditions for seed germination can be provided.

Hormonal Treatments

Hormonal treatments involve the use of plant hormones, including gibberellins, to break physiological dormancy, which stimulates the growth and development of seeds. The application of gibberellins to seeds aims at breaking dormancy to enhance germination. Practical applications of hormonal treatments are utilised in horticulture and agriculture to ensure efficient propagation of seeds.

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Frequently Asked Questions (FAQs)

1. What is seed dormancy and why is it important?

Seed dormancy is a state wherein the seeds do not germinate even in the presence of all favourable conditions. It is an adaptation that makes sure that seeds germinate only when the chances of seedling establishment are more certain. Through this mechanism, germination is synchronised with the seasons, avoiding the risk of premature sprouting, very dangerous for plant survival.

2. How does scarification help in breaking seed dormancy?

Scarification enables germination by physically and chemically altering the seed coat to allow penetration by water and gases. It might involve mechanical abrasion or chemical treatments that weaken or remove the hard seed coat, therefore allowing the embryo inside to reuptake water and initiate germination.

3. What are the different types of seed dormancy?

The different kinds of dormancy exhibited by seeds include:

Inherent Dormancy: Already found in the seed due to either physiological stages or hard seed coats.

Induced Dormancy: Due to environmental factors such as temperature or water.

Enforced Dormancy: Harsh conditions or physical obstruction to germination

Combination Dormancy: It combines the physical, physiological, and morphological aspects that act collectively against germination.

4. How do environmental conditions affect seed dormancy?

Environmental factors such as temperature, light, and moisture play major roles in seed dormancy. Low temperature may, for example, overcome physiological dormancy through stratification. Illumination can induce germination in those having photoperiodic requirements. Adverse conditions, on the other hand, may maintain dormancy or induce a condition when seeds remain dormant until favourable conditions improve.

5. What methods are used to overcome seed dormancy in agriculture?

Some of the techniques practised in agriculture to overcome seed dormancy include:

Scarification: The breaking of seed coats either mechanically or chemically for good water uptake.
Stratification: This involves the treatment of seeds under favourable conditions, such as cold or warm temperatures imitating seasonal changes.
Treatments with Light and Temperature: Specific light and temperature treatments stimulate germination.
Hormonal Treatments: Gibberellins, a type of plant hormone, may be applied to stimulate germination in break physiological dormancy.

6. How does abscisic acid (ABA) contribute to seed dormancy?

Abscisic acid (ABA) is a plant hormone that plays a crucial role in seed dormancy. It inhibits germination by suppressing embryo growth and preventing water uptake. ABA levels typically increase during seed maturation and decrease when conditions are favorable for germination.

7. What is the role of the seed coat in maintaining dormancy?

The seed coat plays a crucial role in maintaining dormancy by acting as a physical barrier to water and oxygen uptake. It can also contain chemical inhibitors that prevent germination. The seed coat's structure and composition are often adapted to the plant's specific ecological niche and dispersal strategy.

8. What is physiological dormancy, and how does it differ from physical dormancy?

Physiological dormancy is caused by internal factors within the seed that prevent germination, such as hormone imbalances or immature embryos. Physical dormancy, on the other hand, is caused by a hard or impermeable seed coat that prevents water uptake. Physiological dormancy often requires specific environmental cues to break, while physical dormancy typically needs mechanical or chemical scarification.

9. How do endogenous biological clocks influence seed dormancy and germination timing?

Endogenous biological clocks, or circadian rhythms, can influence seed dormancy and germination timing. These internal timekeeping mechanisms help seeds respond to seasonal cues like day length or temperature changes, ensuring germination occurs at the most favorable time of year for seedling establishment.

10. What is the concept of bet-hedging in relation to seed dormancy?

Bet-hedging in seed dormancy refers to the strategy where a plant produces seeds with varying degrees of dormancy. This ensures that not all seeds germinate at once, spreading the risk of seedling mortality across different time periods and environmental conditions. It's an evolutionary adaptation that increases the chances of successful reproduction in unpredictable environments.

11. What is seed dormancy and why is it important for plant survival?

Seed dormancy is a temporary state where seeds do not germinate even under favorable conditions. It's important for plant survival because it prevents seeds from germinating at inappropriate times, such as during brief warm spells in winter, ensuring they sprout when conditions are optimal for seedling growth and establishment.

12. How does seed dormancy contribute to the formation of soil seed banks?

Seed dormancy allows seeds to remain viable in the soil for extended periods, forming soil seed banks. These banks serve as reservoirs of biodiversity, allowing plant populations to recover after disturbances. The varying dormancy levels of different seeds in the bank ensure gradual emergence over time, contributing to ecosystem stability and resilience.

13. What is the relationship between seed dormancy and seed longevity?

Seed dormancy and longevity are often related. Seeds with strong dormancy mechanisms tend to have longer lifespans in the soil, as the same adaptations that prevent premature germination also protect against deterioration. However, the relationship is not always straightforward, as some short-lived seeds can also exhibit strong dormancy.

14. What role does seed dormancy play in preventing germination of weed seeds in agricultural settings?

Seed dormancy in weed species can be both a challenge and a benefit in agriculture. It allows weed seeds to persist in the soil, making long-term management difficult. However, dormancy also prevents all weed seeds from germinating at once, which would overwhelm crops. Understanding weed seed dormancy helps in developing effective weed control strategies, such as timing of tillage or herbicide application.

15. How do seed dormancy mechanisms protect against vivipary in non-mangrove species?

In non-mangrove species, seed dormancy mechanisms prevent vivipary (premature germination while still on the parent plant) by maintaining high ABA levels or low gibberellin sensitivity in maturing seeds. This ensures that seeds do not germinate until they have fully developed and been dispersed, even if environmental conditions on the parent plant are favorable for germination.

16. How do environmental factors like temperature and light affect seed dormancy?

Environmental factors can influence seed dormancy in various ways. For example, some seeds require exposure to cold temperatures (stratification) to break dormancy, while others may need light or alternating temperatures. These factors often mimic natural seasonal changes, signaling optimal conditions for germination.

17. What is scarification, and how does it help break seed dormancy?

Scarification is a process of breaking or weakening the seed coat to allow water and oxygen to reach the embryo. This can be done mechanically (e.g., scratching the seed coat), chemically (using acids), or naturally (through microbial action or passing through an animal's digestive system). Scarification helps break physical dormancy caused by hard seed coats.

18. What role do gibberellins play in breaking seed dormancy?

Gibberellins are plant hormones that promote seed germination by counteracting the effects of ABA. They stimulate the production of enzymes that break down stored food reserves in the seed, weaken the seed coat, and promote embryo growth. Increasing gibberellin levels or sensitivity can help break dormancy in many seed types.

19. How does after-ripening contribute to breaking seed dormancy?

After-ripening is a process where dry seeds gradually lose dormancy over time when stored under specific conditions (usually warm and dry). This process involves internal changes in the seed, such as alterations in hormone levels or sensitivity, which eventually allow the seed to germinate when exposed to favorable conditions.

20. How does seed size relate to dormancy and germination strategies?

Seed size often correlates with dormancy and germination strategies. Larger seeds typically have more stored resources and may exhibit less dormancy, as they can support seedling growth for longer periods. Smaller seeds often have more complex dormancy mechanisms, as they need to ensure germination occurs under optimal conditions for rapid establishment.

21. What is the difference between primary and secondary dormancy?

Primary dormancy is induced during seed development on the parent plant, preventing immediate germination after seed dispersal. Secondary dormancy occurs after seed dispersal when unfavorable environmental conditions cause non-dormant seeds to enter a dormant state.

22. How does vivipary differ from typical seed dormancy, and in which plants is it common?

Vivipary is a phenomenon where seeds germinate while still attached to the parent plant, bypassing the dormant stage. It's common in mangrove plants, allowing seedlings to establish quickly in challenging tidal environments. This strategy differs from typical seed dormancy, which delays germination until after seed dispersal.

23. How do seed dormancy mechanisms differ between annual and perennial plants?

Annual plants often have less complex dormancy mechanisms as they rely on rapid germination and growth to complete their life cycle in one season. Perennial plants, which live for multiple years, may have more sophisticated dormancy mechanisms to ensure long-term survival and optimal timing of germination across multiple seasons.

24. How do seed banks use dormancy mechanisms to preserve biodiversity?

Seed banks utilize natural dormancy mechanisms to store seeds for long periods. By maintaining seeds in a dormant state through controlled temperature and humidity, seed banks can preserve plant genetic diversity for future use in conservation, research, or agriculture. Understanding dormancy helps in developing optimal storage conditions for different seed types.

25. What is the significance of seed dormancy in agriculture and crop breeding?

In agriculture, understanding seed dormancy is crucial for crop management and breeding. Farmers need seeds that germinate uniformly and quickly after planting. Plant breeders often work to reduce dormancy in crop species to improve germination rates and timing. However, some level of dormancy can be beneficial in preventing pre-harvest sprouting in cereals.

26. What is the ecological significance of seed dormancy in fire-prone ecosystems?

In fire-prone ecosystems, many plant species have evolved seeds with dormancy mechanisms that are broken by fire or smoke. This adaptation ensures that seeds germinate after a fire when competition is reduced and nutrients are abundant. It helps maintain biodiversity and ecosystem resilience in these environments.

27. How do chemical inhibitors in seeds contribute to dormancy?

Chemical inhibitors in seeds, such as phenolic compounds or ABA, contribute to dormancy by suppressing embryo growth or enzyme activity necessary for germination. These inhibitors may be present in the seed coat, endosperm, or embryo itself. Their gradual breakdown or leaching can be part of the dormancy-breaking process.

28. What is morphophysiological dormancy, and how does it differ from other types?

Morphophysiological dormancy combines both morphological immaturity of the embryo and physiological inhibiting mechanisms. Seeds with this type of dormancy require a period of after-ripening for the embryo to fully develop, as well as specific environmental conditions to overcome physiological barriers. It's more complex than simple morphological or physiological dormancy alone.

29. How do seed dormancy strategies vary across different climate zones?

Seed dormancy strategies vary across climate zones to match local environmental conditions. For example, seeds in temperate regions often require cold stratification to break dormancy, mimicking winter conditions. In contrast, seeds from arid regions may have physical dormancy to withstand long dry periods, while tropical seeds might have less pronounced dormancy due to more stable year-round conditions.

30. What is the role of nitrate in breaking seed dormancy, and how is this relevant to ecological succession?

Nitrate can break seed dormancy in many species by stimulating germination. This mechanism is ecologically relevant as it allows seeds to detect improved soil fertility, often associated with disturbances or the early stages of ecological succession. Seeds responding to nitrate are more likely to germinate in nutrient-rich environments favorable for seedling establishment.

31. How does seed dormancy contribute to the evolution of plant life history strategies?

Seed dormancy is a key component of plant life history strategies, influencing how plants cope with environmental variability and competition. It allows for temporal dispersal, spreading germination over time to reduce sibling competition and risk from environmental hazards. The evolution of different dormancy types reflects adaptations to specific ecological niches and selective pressures.

32. What is the concept of dormancy cycling, and how does it affect seed bank dynamics?

Dormancy cycling refers to the seasonal changes in seed dormancy depth in response to environmental cues. Seeds may enter and exit dormancy multiple times before germinating. This process affects seed bank dynamics by ensuring that seeds germinate only when conditions are consistently favorable, not just during brief periods of suitable conditions.

33. How do epigenetic mechanisms contribute to seed dormancy regulation?

Epigenetic mechanisms, such as DNA methylation and histone modifications, can regulate seed dormancy without changing the underlying DNA sequence. These modifications can be influenced by environmental conditions experienced by the parent plant or the seed itself, allowing for flexible adaptation to changing environments across generations.

34. What is the significance of seed dormancy in conservation efforts for endangered plant species?

Seed dormancy is crucial in conservation efforts for endangered plants as it allows for long-term seed storage in seed banks. Understanding species-specific dormancy requirements is essential for successful germination and reintroduction programs. It also helps in maintaining genetic diversity by preserving seeds from different populations and years.

35. How does seed dormancy relate to the concept of seed priming in agriculture?

Seed priming is a technique used to improve germination speed and uniformity by partially hydrating seeds before planting. It works by initiating metabolic processes associated with germination without allowing full germination. Understanding seed dormancy mechanisms is crucial for developing effective priming techniques that break dormancy without compromising seed viability.

36. What is the role of reactive oxygen species (ROS) in seed dormancy and germination?

Reactive oxygen species (ROS) play a dual role in seed biology. At low levels, ROS can act as signaling molecules that promote the breaking of dormancy and stimulate germination. However, at high levels, ROS can cause oxidative damage to cellular components. The balance of ROS production and scavenging is crucial in regulating the transition from dormancy to germination.

37. How do seed dormancy mechanisms differ between orthodox and recalcitrant seeds?

Orthodox seeds, which can be dried and stored for long periods, often have well-developed dormancy mechanisms. Recalcitrant seeds, which cannot survive drying and must germinate quickly after dispersal, typically have little to no dormancy. This difference reflects their contrasting ecological strategies and storage behaviors.

38. What is the concept of dormancy depth, and how does it vary among seeds of the same species?

Dormancy depth refers to the intensity of the dormant state, or how difficult it is to break dormancy and induce germination. Within a single species, seeds can exhibit varying dormancy depths due to genetic diversity, environmental conditions during seed development, or the position of the seed on the parent plant. This variation contributes to the bet-hedging strategy in natural populations.

39. How do seed dormancy mechanisms interact with seed dispersal strategies?

Seed dormancy mechanisms often complement dispersal strategies. For example, seeds dispersed by wind might have dormancy mechanisms that prevent germination until they reach the ground and experience specific soil conditions. Seeds dispersed by animals might have dormancy broken by passage through the digestive tract. These interactions ensure seeds germinate in suitable locations and at appropriate times.

40. What is the role of temperature fluctuations in breaking seed dormancy?

Temperature fluctuations can break dormancy in many species by signaling changing seasons or gaps in vegetation cover. Alternating temperatures can affect hormone balances, enzyme activities, or gene expression patterns within the seed. This mechanism helps ensure seeds germinate when conditions are likely to be favorable for seedling establishment.

41. How does seed dormancy contribute to the maintenance of genetic diversity in plant populations?

Seed dormancy contributes to genetic diversity by creating a soil seed bank with seeds from multiple generations. This temporal spread of germination allows for genetic mixing between different cohorts and helps preserve rare alleles that might be lost if all seeds germinated simultaneously. It also buffers populations against short-term environmental fluctuations that could otherwise lead to genetic bottlenecks.

42. What is the significance of seed dormancy in invasive plant species?

Seed dormancy in invasive species can contribute to their success by allowing them to persist in new environments and emerge when conditions are favorable. Long-lived seed banks of invasive plants can make eradication efforts challenging. However, understanding the dormancy mechanisms of invasive species can also provide insights for developing targeted control strategies.

43. How do seed dormancy mechanisms adapt to climate change?

As climate patterns shift, seed dormancy mechanisms may need to adapt to ensure germination timing remains optimal. This could involve changes in temperature or moisture requirements for breaking dormancy. Plants with flexible dormancy mechanisms or those capable of rapid evolutionary adaptation may be better equipped to cope with changing climatic conditions.

44. What is the role of seed dormancy in desert annual plants?

In desert annuals, seed dormancy is crucial for survival in unpredictable environments. These plants often produce seeds with varying degrees of dormancy, ensuring that not all seeds germinate after a single rain event. This bet-hedging strategy helps maintain populations through dry years and allows for massive germination events when conditions are exceptionally favorable.

45. How does seed dormancy relate to the concept of seed vigor?

Seed vigor refers to the seed's ability to germinate rapidly and uniformly under various environmental conditions. While dormancy prevents germination, the processes that break dormancy often overlap with those that enhance seed vigor. Managing dormancy effectively in crop seeds is essential for achieving high vigor, which is crucial for successful crop establishment.

46. What is the significance of dormancy-specific gene expression in seeds?

Dormancy-specific gene expression involves the activation or repression of certain genes that regulate the dormant state. These genes may control hormone synthesis, sensitivity to environmental cues, or metabolic processes. Understanding these genetic mechanisms is crucial for developing crops with desired dormancy characteristics and for predicting how wild plant populations might respond to environmental changes.

47. How do seed dormancy mechanisms differ between gymnosperms and angiosperms?

Gymnosperm seeds often have less complex dormancy mechanisms compared to angiosperms. Many gymnosperm seeds rely more on physical dormancy imposed by the seed coat or physiological dormancy that can be broken by cold stratification. Angiosperms, with their greater diversity, have evolved a wider range of dormancy mechanisms, including more complex forms of physiological and morphophysiological dormancy.

48. What is the role of seed dormancy in plants with mast seeding behavior?

In mast seeding plants, which produce large seed crops at irregular intervals, seed dormancy plays a crucial role. It allows seeds from mast years to persist in the soil, forming a seed bank that can germinate over several years. This strategy helps saturate seed predators during mast years while ensuring some seeds remain viable for future germination, even in years with low seed production.

49. How does seed dormancy affect the timing of germination in relation to seasonal changes?

Seed dormancy mechanisms often evolve to synchronize germination with seasonal changes that provide optimal conditions for seedling establishment. For example, seeds might require a period of cold followed by warming temperatures to break dormancy, ensuring spring germination. This timing helps seedlings avoid harsh winter conditions or summer drought, depending on the species and its habitat.

50. What is the significance of dormancy polymorphism within a single plant species?

Dormancy polymorphism, where a single plant produces seeds with different dormancy characteristics, is an important bet-hedging strategy.