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Seed Germination Definition and Process in 5 Basic Stages

As a student, have you ever taken the time to understand what seed germination is and how it works? If so, then this blog post is perfect for you! During these five basic stages of seed germination, readers will gain an understanding of the different components that lead up to vegetation growth. Read on as we detail what exactly happens from when a seed is planted in soil to when plants start popping out through the surface. Let’s take your understanding of seeds and their germination one step further!

Definition of Seed Germination 

Seed germination is the process by which a plant grows from a seed. In another word; Seed germination is the process of active growth. The embryo is resulting in the rupture of the seed coat and emergence of the new young plant under the favorable condition of water, oxygen, temperature, and sometimes light. 

Botanically, germination may be defined as the emergence and development of the seed embryo of those essential structures that for the kind of seeds in questions are indicated to produce a normal plant under favourable condition. It is expressed in terms of percentage.

Process of seed germination

The germination process may be divided into the following stages-

  1. Imbibition of water
  2. Enzymatic and respiratory activities
  3. Digestion and translocation of food
  4. Assimilation
  5. Growth

Imbibition of water

In a moist medium, the seed absorbs water with or without any intervallic lack period. The water absorption depends upon the kinds of seeds. In legumes, water enters the seed through the strophiole and others through Hilum tissue. Some species absorb water from all parts of the seed coat. 

The water uptake is very rapid in cereal grain. The growing embryo is specially separated from storage endosperm then the metabolic activity is enhanced. The seed protein contains hydration of water and also absorb a sufficient amount of moisture. The swelling of the seed often causes the bursting of the seed coat in many species, like swelling of both water and gas and emerging of the growing point.

Enzymatic and respiratory activities

This stage is characterized by the initiation of cellular activity with the appearance of specific enzymes and increases the respiratory rate. The storage tissue of endosperm and cotyledon of germinating seeds, hydrology whose activity promotes mobilization of the reserved compound in seed and activation of the respiratory enzyme. 

In cerealone of the detectable features of the metabolic activity is the activation of mRNA accomplished by an increase in the embryo’s capacity to synthesize protein. This follows the imbibition of water for only a few minutes. Polysome begins to increase with the respiration rate and extension of some cell within the first 12-16 hours, the synthesis of new DNA and RNA particularly nil. 

By this time, there has been some extension growth of the existing cell. The early stages of meiotic cell division can be recognized. During the first 24 hours, the extension and division depend entirely on amino acid, fats, and soluble carbohydrate stored in the embryo. 

During this period, a considerable amount of gibberellin is secreted by the embryo. The primary mode of action of gibberellin on stimulating RNA synthesis or the synthesis of α-amylase. It plays an essential role in nucleic acid metabolism and protein synthesis.   

Digestion and translocation of food

Digestion is the chemically breaking down of complex food to a simple one done by the hydrolytic enzyme. The starch, lipid and protein is digested by diastase (α-amylase) lipase and protease into sugar, fatty acid and amino acid. Digested foods such as Glucose, Fructose, maltose, Fatty acid, Amino acid are translocated to the active growing area.


Assimilation is the process by which the digested food becomes a part of the living protoplasm. The assimilation takes the place of the meristematic area to provide cellular activity growth of embryo and conservation into new cell component.


The seedling grows by cell division, enlargement and differentiation of cell at the growing point. The growth and development of seedling depend upon food reserved in the seed. The emergence of Plumule above the ground brings the plant under the influence of light and result in the suppression of mesocycle, hypocotyl or epicotyl growth and stimulating the formation of chlorophyll. 

They are followed a transition period during which photosynthesis gradually assumes. Seedling of wheat becomes completely independent when the second leaf fully emerges and the third just emerging. Cucumber seedling becomes independent soon after the unfolding of the cotyledon.

Factor Affecting Seed Germination 

  • Water
  • Oxygen
  • Temperature
  • Light or Darkness            

1. Water

It is required for germination. Mature and roller coaster seeds are often dehydrated. They need to take in significant amounts of water relative to the dry weight of the seed before cellular metabolism and growth can resume. Most seeds need enough water to moisten the seeds but not enough to soak them. The uptake of water by seeds is called imbibition, which leads to the swelling and the breaking of the seed coat.

When seeds are formed, most plants store a food reserve with the seed, such as starch, proteins, or oils. This food reserve provides nourishment to the growing embryo. When the seed imbibes water, hydrolytic enzymes are activated, which break down these stored food resources into metabolically useful chemicals. After the seedling emerges from the seed coat and starts growing roots and leaves, the seedling’s food reserves are typically exhausted; at this point, photosynthesis provides the energy needed for continued growth, and the seedling now requires a continuous supply of water, nutrients, and light.

2. Oxygen

It is required by the germinating seed for metabolism. Oxygen is used in aerobic respiration, the main source of the seedling’s energy until it grows leaves. Oxygen is an atmospheric gas found in soil pore spaces; if a seed is buried too deeply within the soil or the soil is waterlogged, the seed can be oxygen-starved. Some seeds have impermeable seed coats that prevent oxygen from entering the seed, causing a type of physical dormancy which is broken when the seed coat is worn away enough to allow gas exchange and water uptake from the environment.

3. Temperature

It affects cellular metabolic and growth rates. Seeds from different species and even seeds from the same plant germinate over a wide range of temperatures. Seeds often have a temperature range within which they will germinate, and they will not do so above or below this range. Many seeds germinate at temperatures slightly above 60-75oF (16-24oC) [room-temperature if you live in a centrally heated house], while others germinate just above freezing, and others germinate only in response to alternations in temperature between warm and cool.

Some seeds germinate when the soil is cool 28-40oF (-2 – 4oC), and some when the soil is warm 76-90oF (24-32oC). Some seeds require exposure to cold temperatures (vernalization) to break dormancy. Some seeds in a dormant state will not germinate even if conditions are favorable. Seeds that are dependent on temperature to end dormancy have a type of physiological dormancy. For example, seeds requiring the cold of winter are inhibited from germinating until they take in water in the fall and experience cooler temperatures.

Four degrees Celsius is cool enough to end dormancy for most cool dormant seeds, but some groups, especially within the family Ranunculaceae and others, need conditions cooler than -5oC. Some seeds will only germinate after hot temperatures during a forest fire that cracks their seed coats; this is a type of physical dormancy.

Most common annual vegetables have optimal germination temperatures between 75-90oF (24-32oC), though many species (e.g., radishes or spinach) can germinate at significantly lower temperatures, as low as 40oF (4oC), thus allowing them to be grown from seeds in cooler climates. Suboptimal temperatures lead to lower success rates and longer germination periods.

4. Light or darkness

It can be an environmental trigger for germination and is a type of physiological dormancy. Most seeds are not affected by light or darkness, but many seeds, including species found in forest settings, will not germinate until an opening in the canopy allows sufficient light for the seedling growth.

Scarification mimics natural processes that weaken the seed coat before germination. In nature, some seeds require particular conditions to germinate, such as the heat of a fire (e.g., many Australian native plants) or soaking in a body of water for a long period. Others need to be passed through an animal’s digestive tract to weaken the seed coat enough to allow the seedling to emerge.


Seed germination is the pivotal part of any plant’s life cycle. It requires particular environmental conditions and ideal temperatures to be successful. Whether it’s a large redwood tree or a tiny daisy, growth begins with successful seed germination. As this blog post has demonstrated, understanding what officially constitutes a plant “germinating” can help us better appreciate and, potentially, cultivate our own personal garden full of plants. We’ve learned about the process and how it occurs in 5 different stages, though they vary slightly depending on the plant species and environmental factors present. Now that you understand the basics of seed germination better than ever before, why not test out your knowledge? Challenge yourself- start growing in your backyard or balcony and monitor your progress. What do you know now more about Seed Germination? Let me know in the comment below!

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