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Seed Germination – Explanation and Process

Sep 9, 2022
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Key Concepts

  • Seed
  • Seed Germination
  • Sunlight
  • Oxygen
  • Water
  • Temperature
  • Seed Dormancy

Introduction

Seed germination in sunflower

Seed germination is the basic process by which various plant species develop from a single seed into a plant.  

This procedure has an impact on crop output and quality. 

Process of seed germination

The seeds rapidly absorb water during the early stages of germination, causing swelling and softening of the seed coat at an ideal temperature. Imbibition is the name for this phase.  

Imbibition process

The activation of enzymes kickstarts the growth process. 

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The seed’s internal physiology is activated, and it begins to breathe, create proteins, and metabolize the food that has been stored. Seed germination is in a lag phase. 

Radicle arises to create a primary root after the seed coat ruptures. The seed begins to take up water from the ground.  

The shoot starts to develop upwards once the radicle and plumule emerge. 

Plumule forms the shoot system. 

The seed cell becomes metabolically active, elongates, and divides in the last stage of seed germination, giving rise to the seedling. 

parallel
Radicle, plumule, and activation of enzymes in seed germination

Explanation

Here are some key criteria for a seed to germinate and grow into a seedling and eventually a plant. 

Water

Seed germination requires a lot of water. Some seeds are very dry and require a large amount of water in comparison to their dry weight.  

Seed germination is aided by the presence of water.  

Water aids by giving protoplasm with the essential hydration, dissolved oxygen for the developing embryo, softening seed coverings, and increasing seed permeability.  

It also aids in seed rupturing and transforms insoluble food into soluble form for transfer to the embryo. 

Requirement of water

Oxygen

is a vital source of energy for seed development. It is essential for metabolism by the growing seed and is employed in aerobic respiration until the seed is able to generate its own green leaves.  

The holes of soil particles contain oxygen, but if the seed is buried too deep, it will be deprived of it. 

Temperature

A moderate temperature of roughly 25-30 °C is required for seed germination. Various seeds, obviously, need different temperatures to thrive. 

Some seeds require a certain temperature range of 5 to 40 °C, with some seeds requiring a lower or higher temperature. 

Factors required for seed germination

Light

Environmental triggers can be light for seed germination. Many seeds are not able to germinate unless they are exposed to sunshine. 

Under the above-stated favorable conditions, the seed germination process begins.  

The embryo grows rapidly, rupturing the covering layers and allowing the radicle to emerge. Germination is said to be complete when the radicle emerges. 

Seed germination is influenced by a number of key elements, among them are: 

External Factors

Seed germination is influenced by a lack of or increased supply of water.  

Temperature: When the temperature falls below a moderate level, seed germination is slowed, and fungus development is encouraged.  

Germination can sometimes come to a halt when the temperature rises above a certain point.  

Oxygen: As seeds germinate, they take in a lot of oxygen and release the energy that they need to thrive. As a result, seed germination is harmed by a lack of oxygen. 

Factors that affect the germination of seed

Internal Factors  

Seed dormancy is an evolutionary adaptation or a situation in which seeds are unable to germinate even in ideal conditions.  

The fundamental cause of these circumstances is that they require a period of rest before they can germinate.  

These situations might change over time, from days to months to years. Light, water, heat, gases, seed coverings, and hormone structures make up these circumstances. 

Seed dormancy
  • During seed dormancy, the water and gas-resistant seed coat inhibit water intake and oxygen exchange. 
  • Undeveloped or immature embryo seeds do not germinate. 
  • Plant growth regulators are found in some seeds, and they prevent seed germination. 
  • Some seeds take longer to germinate. 

Summary

  • Seed germination is the basic process by which various plant species develop from a
    single seed into a plant.
  • The seeds rapidly absorb water during the early stages of germination, causing swelling
    and softening of the seed coat at an ideal temperature. Imbibition is the name for this
    phase.
  • The seed’s internal physiology is activated, and it begins to breathe, create proteins, and
    metabolize the food that has been stored. Seed germination is in a lag phase.
  • The activation of enzymes kickstarts the growth process.
    The shoot starts to develop upwards once the radicle and plumule emerge.
    Plumule forms the shoot system.
  • Water, light, oxygen, and temperature are some key criteria for a seed to germinate and
    grow into a seedling and eventually a plant.
  • Seed dormancy is an evolutionary adaptation or a situation in which seeds are unable to
    germinate even in ideal conditions.
  • During seed dormancy, the water and gas-resistant seed coat inhibits water intake and
    oxygen exchange.
  • Undeveloped or immature embryo seeds do not germinate.
    Plant growth regulators are found in some seeds, and they prevent seed germination.
  • Some seeds take longer to germinate.

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