Seed Longevity and Germination Quiz
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Questions and Answers

What factors lead to lower longevity of seeds?

  • Immature seed (correct)
  • High food reserves
  • Healthy environmental conditions
  • Excessive moisture (correct)

    • Higher temperatures and moisture content are conducive to longer seed longevity.

    False

    At what depth below the permafrost were the 32,000-year-old seeds found?

    124 feet

    Lower longevity in seeds can occur due to immature seeds, low food reserves, drought conditions, disease, and __________.

    <p>physical damage</p> Signup and view all the answers

    Match the following conditions to their effects on seed longevity:

    <p>Immature seed = Lower longevity High moisture content = Increased disease risk Drought conditions = Reduced growth Physical damage = Lower longevity</p> Signup and view all the answers

    What causes germination to occur?

    <p>Acceptable environmental conditions are present</p> Signup and view all the answers

    During germination, the plumule emerges as the first structure.

    <p>False</p> Signup and view all the answers

    What is the first part of the seed to emerge during germination?

    <p>Radicle</p> Signup and view all the answers

    In monocot germination, the _____________ always remains below ground.

    <p>cotyledon</p> Signup and view all the answers

    What type of germination occurs when the cotyledons are lifted above the ground?

    <p>Epigeal germination</p> Signup and view all the answers

    In hypogeal germination, the cotyledons remain ____________.

    <p>below ground</p> Signup and view all the answers

    Match the following germination terms with their definitions:

    <p>Epigeal = Cotyledons above ground Hypogeal = Cotyledons below ground Radicle = First structure to emerge Plumule = Develops into the shoot</p> Signup and view all the answers

    What structure protects the shoot during its emergence in monocots?

    <p>Coleoptile</p> Signup and view all the answers

    What prevents germination due to physical factors?

    <p>Seed coat dormancy</p> Signup and view all the answers

    Scarification is the process of applying heat to seeds to promote germination.

    <p>False</p> Signup and view all the answers

    What are the two types of dormancy mentioned in the content?

    <p>Exogenous and endogenous dormancy.</p> Signup and view all the answers

    Seeds often require exposure to ____________ temperatures for stratification.

    <p>low</p> Signup and view all the answers

    How can exogenous dormancy be overcome in a lab setting?

    <p>Scarification</p> Signup and view all the answers

    Match the following dormancy types with their overcoming strategies:

    <p>Exogenous Dormancy = Scarification or heat treatment Endogenous Dormancy = Stratification or chemical block</p> Signup and view all the answers

    What is hypogeal germination?

    <p>Germination where the cotyledons remain underground</p> Signup and view all the answers

    Which factor can increase the occurrence of hard seeds in legumes?

    <p>Low soil moisture</p> Signup and view all the answers

    What role does the fungus play regarding shadscale plant seeds?

    <p>It scarifies the seeds, allowing them to germinate.</p> Signup and view all the answers

    Larger seeds should be planted deeper than smaller seeds for successful germination.

    <p>True</p> Signup and view all the answers

    What is dormancy in seeds?

    <p>Dormancy is a survival mechanism that allows seeds to remain viable but not germinate until conditions are favorable.</p> Signup and view all the answers

    Successful germination is dependent on the seedling becoming self-sustaining before the __________ in the seed is used up.

    <p>food</p> Signup and view all the answers

    Match the types of dormancy with their descriptions:

    <p>Exogenous Dormancy = Dormancy due to physical constraints Endogenous Dormancy = Dormancy due to internal factors Double Dormancy = Combination of exogenous and endogenous dormancy</p> Signup and view all the answers

    What is a factor that promotes good germination?

    <p>Seed viability</p> Signup and view all the answers

    Seeds in a dormant state cannot be considered viable.

    <p>False</p> Signup and view all the answers

    The process that allows staggered germination is called __________.

    <p>dormancy</p> Signup and view all the answers

    What is the purpose of stratification in seeds?

    <p>To prepare the seed for winter survival</p> Signup and view all the answers

    Chemicals that block germination can include salts and ammonia-releasing compounds.

    <p>True</p> Signup and view all the answers

    What happens to seeds during the cold stratification period that allows germination to begin?

    <p>Accummulation of plant hormones</p> Signup and view all the answers

    With adequate ____________, the chemicals will leach out of the seed and allow germination.

    <p>moisture</p> Signup and view all the answers

    What is viability in the context of seeds?

    <p>The ability to germinate if conditions are suitable</p> Signup and view all the answers

    Match each plant species with its potential longevity:

    <p>Wheat = 6 to 32 years Barley = 2 to 10 years Oat = 6 to 29 years Wild mustard = up to 60 years Vegetable seeds = 1 to 5 years</p> Signup and view all the answers

    The loss of dormancy in cultivated crops can only lead to advantages.

    <p>False</p> Signup and view all the answers

    The longest known seed longevity reported was for a seed that was ____________ years old.

    <p>32,000</p> Signup and view all the answers

    What happens if there are large pockets of air in the soil?

    <p>Soil moisture will evaporate into the air.</p> Signup and view all the answers

    Waterlogged soils provide sufficient oxygen for germination.

    <p>False</p> Signup and view all the answers

    What is the optimum temperature for germination of cereal crops?

    <p>15°C</p> Signup and view all the answers

    If there is insufficient water, germination may begin but not be sufficient to complete it due to _____ conditions.

    <p>dry</p> Signup and view all the answers

    Which of the following factors affects the rate of imbibition in seeds?

    <p>Seed coat permeability</p> Signup and view all the answers

    Most plants can only germinate in darkness.

    <p>False</p> Signup and view all the answers

    What term refers to the breakdown of seeds that sit too long during germination?

    <p>seed decay</p> Signup and view all the answers

    Match the following conditions with their effects on germination:

    <p>Too much water = Inhibits germination Too little water = Incomplete germination Sufficient oxygen = Supports germination Darkness for certain seeds = Promotes germination</p> Signup and view all the answers

    Study Notes

    Germination and Embryo Growth and Development

    • Plant growth begins with germination and the emergence of the seedling.
    • Plant growth involves stages like vegetative stage, floral initiation, flowering, pollination and zygote formation, fruit and seed maturity, and senescence.
    • Senescence is a natural process where the plant deteriorates and dies. It's not dormancy, which is when normal functions are suspended to conserve energy until conditions improve.
    • Germination is a sequence of events beginning with water absorption, leading to seedling growth and development.
    • Water absorption, called imbibition, is crucial for germination. Cereals need roughly 50% moisture, and beans need about 75%.
    • Water activates enzymes that break down stored food, and also increases respiration. This process is crucial to turn stored food into energy to build new cells.
    • The level of physiological activity drastically increases during germination due to enzyme activation and synthesis.
    • Enzymes break down stored food into simpler compounds to provide energy and nutrients for growth.
    • For example, in cereal crops, the embryo releases a hormone (gibberellin) activating enzymes in the aleurone layer. Alpha amylase converts starches to glucose for the embryo's growth.
    • Water imbibition is affected by factors including soil firmness and soil water content.
    • Firm soil allows close moisture contact with the seed, making it easier to absorb.
    • Large air pockets in the soil cause moisture loss to the atmosphere, affecting absorption.
    • Too much or too little water inhibits germination. Waterlogged soil has insufficient oxygen for germination, which is needed for respiration.
    • The rate of imbibition depends on the seed's composition. Proteins absorb more water (than starch), so the embryo absorbs more water than the endosperm.
    • Some seeds have impermeable seed coats that initially resist water absorption.
    • Each plant has an optimum temperature for germination and a range that will inhibit it if it goes beyond.
    • Cereal crops can germinate just above freezing, and up to 37°C. The optimum temperature for cereal germination is 15°C. Warmer-season crops like corn need higher temperatures (10°C) for germination.
    • Oxygen is essential for respiration, a process for using stored food to create the first leaves for photosynthesis. Insufficient oxygen due to planting too deep or waterlogged soil can inhibit germination.
    • Light is not always needed for all plants to germinate. Most plants can germinate in light or dark, but some require light.
    • A seed's viability (being alive and capable of germination with proper conditions) impacts successful germination.
    • Seeding depth affects the availability of oxygen and moisture to the seed. Deeper planting can deplete conditions for seeds to reach the surface. Larger seeds (generally) need deeper planting than smaller ones.
    • Successful germination depends on seedlings becoming self-sufficient before the seed's food stores are used.
    • Dormancy is a survival mechanism for plants that delays germination until conditions improve, such as favorable temperatures or sufficient moisture.
    • Seeds are viable (alive) but prevent germination in unfavorable conditions.
    • Germination can be staggered in time, meaning different seeds sprout at different times for survival purposes.
    • Plants have either exogenous (physical constraints like seed coat) or endogenous dormancy (physiological or embryonic conditions). Some seeds have both.
    • Methods like scarification (mechanical scratching to rupture the coat), heat treatment and acid treatment can overcome exogenous dormancy.
    • Strategies to cope with endogenous dormancy include stratification (exposure to low temperatures and moisture).
    • Chemicals in some seeds block germination. With enough moisture, these chemicals can leach out to enable germination.
    • Many crops have lost or selected against their dormancy traits for easier production and seed use.
    • The loss of dormancy to allow quick germination can result in problems with sprouting in the field.
    • Seed viability is the ability for germination in suitable conditions; it declines. Seed longevity is the time a seed can stay dormant and viable; it depends on factors such as plant type, growing conditions, and storage methods.

    Embryo Growth and Development

    • The radicle (root) and plumule (shoot) grow through cell division and enlargement, making the cells bigger.
    • Food from the seed is transported to growing parts.
    • The seed coat (testa) is broken, and the radicle grows down to absorb moisture and nutrients.
    • The plumule gets out into sunlight and starts photosynthesis.
    • The embryo becomes a seedling.

    Monocot Germination

    • The monocot embryo has a protective structure (coleoptile) that surrounds the plumule (shoot.)
    • The radicle grows into the root system.
    • The coleoptile emerges from the soil, followed by the first true leaf, emerging from the coleoptile.
    • The cotyledon remains below ground in monocots.

    Dicot Germination

    • Dicot germination is of two types: epigeal (cotyledon emerges above ground) and hypogeal (cotyledon stays below ground)
    • In epigeal germination, the hypocotyl (stem below cotyledons) pushes the cotyledons above ground, functioning as leaves until true leaves develop.
    • In hypogeal germination, the cotyledon remains below ground. The epicotyl (the stem above the cotyledon) grows, bringing the plumule above ground.

    Conditions to Promote Good Germination

    • Seed viability, seeding depth (to facilitate moisture and oxygen), and seedling vigour impact germination.
    • Seed tests can assess seed viability to improve germination outcomes.
    • The depth of the seed affects oxygen and moisture availability.
    • Successfully germinating seedling becomes self-sufficient before exhausting the seed's stored nutrients.

    Other Factors Affecting Germination: Dormancy

    • Dormancy prevents germination in unfavorable conditions.
    • Dormancy may be Exogenous (physical seed coat constraint) or Endogenous (physiological constraint.)
    • Methods to break exogenous dormancy include scarification (mechanical scratching, acid treatment, heat treatment). Examples are weathering, animals digestive action.
    • Strategies to break endogenous dormancy include stratification (exposure to low temperatures and moisture).
    • Chemicals in seeds may block germination; adequate moisture causes these chemicals to leach out, initiating germination.

    Viablity and Longevity

    • Viability is the ability of a seed to germinate under suitable conditions; it declines.
    • Longevity is the time a seed stays dormant and viable; factors like plant species, growing conditions and storage conditions impact longevity.
    • Examples show longevity differences between plant species (e.g., wheat to 32 years; wild mustard to 60 years).
    • Plant age, food reserves, disease and physical damage shorten seed longevity.
    • Higher temperature and moisture in storage decrease longevity due to faster seed respiration and a higher risk of disease.

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    Plant Science L14 - Germination and Embryo Growth and Development

    Description

    Test your knowledge on the factors affecting seed longevity and the process of germination. This quiz will cover topics such as conditions for seed viability, germination types, and specific structures involved in seedling development. Perfect for students studying plant biology or seed science.

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