Seed Dormancy and Survival Mechanisms

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Questions and Answers

What is the purpose of soaking seeds in hot water followed by cold water for 24 hours?

To enhance the germination rate immediately

To facilitate the removal of inhibitors (correct)

To fully hydrate the seeds

To promote acidification of the seed coat

Which chemical is used for soaking seeds to modify a hard or impermeable seed covering?

Potassium nitrate

Thiourea

Sulphuric acid (correct)

Gibberellic acid

What is cold stratification primarily used for?

To increase seed dormancy

To accelerate the drying process

To stimulate physiological changes within the seed embryo (correct)

To prevent moisture loss

What type of environment is required during cold stratification?

Cool temperatures with abundant moisture and oxygen (B) Signup and view all the answers

How long can post-harvest dormancy last in freshly harvested seeds stored under dry conditions?

From a few days to several months (B) Signup and view all the answers

Which treatment has been found to stimulate germination in many citrus species?

Soaking in gibberellic acid (A) Signup and view all the answers

What should be done to seeds after acid treatment to ensure safety?

Wash them to remove residual acid (C) Signup and view all the answers

What is the main role of endogenous growth promoting substances during cold stratification?

To facilitate germination by increasing their levels (D) Signup and view all the answers

What does dormancy in seeds primarily help to conserve?

Energy (B) Signup and view all the answers

Which type of dormancy is characterized by hard seed coats that prevent germination?

Seed coat dormancy (D) Signup and view all the answers

Which method involves breaking or scratching the seed coats to aid germination?

Mechanical scarification (B) Signup and view all the answers

What is a factor that does NOT contribute to seed dormancy?

Excess soil nutrients (A) Signup and view all the answers

Which type of dormancy requires several weeks to months after harvest for the embryo to mature?

Embryo dormancy (D) Signup and view all the answers

How can chemical inhibitors in seeds be reduced to allow for germination?

By leaching with water (C) Signup and view all the answers

Which of the following is NOT a method to overcome seed dormancy?

Fire treatment (C) Signup and view all the answers

What is double dormancy in seeds?

A combination of seed coat dormancy and embryo dormancy (A) Signup and view all the answers

Study Notes

Dormancy

Dormancy is a state of suspended growth and development in organisms. It helps conserve energy.
Dormancy is a natural survival mechanism, not a failure.

Types of seed dormancy

Seed coat dormancy: The seed coat is hard and impermeable, preventing germination. Examples: Malvaceae, Pits of stone fruits, shells of nuts
Dormancy due to rudimentary embryos: The embryo is not fully developed at the time of seed dispersal. It requires time to mature before it can germinate. Examples: Pinus species, palms
Dormancy due to chemical inhibitors: Seeds contain chemicals that inhibit germination. These inhibitors can be leached out with water or adsorbed by water.
Dormancy due to internal factors: The embryo is physiologically dormant and requires specific conditions, such as moist chilling treatments, to resume growth. Examples: Freshly harvested seeds of apple, grapes, peach, and apricot
Double dormancy: Seeds exhibit both seed coat dormancy and embryo dormancy. Example: Cercis occidentals

Overcoming Dormancy

Mechanical scarification: Physically breaking or scratching the seed coat to make it permeable.
Soaking in water: Softening the seed coat and washing away inhibitors.
Acid treatment: Modifying the seed coat using concentrated hydrochloric acid or sulfuric acid for a brief period.
Cold stratification: Exposing seeds to moisture, oxygen, and cool temperatures to promote physiological changes in the embryo. This process involves placing seeds in a moist medium like sand, peat, or vermiculite and storing them at slightly above freezing temperatures for an extended period, usually one to four months.
Dry storage: Promoting after-ripening in dormant seeds.
Treatment with chemicals: Soaking seeds in solutions of potassium nitrate, gibberellic acid, or thiourea to stimulate germination.

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Description

Explore the fascinating world of seed dormancy, a crucial survival strategy in plants that conserves energy and allows for optimal germination conditions. This quiz covers various types of dormancy, including seed coat dormancy, rudimentary embryos, and more. Test your knowledge on how these mechanisms support plant life.