The Mechanism and Science of Seed Germination

Seed Germination is defined as the transformation of a seed into a young plant or seedling. Before we go further in looking at seed germination processes, let us have a look at what exactly is seed germination from a scientific perspective.

What exactly is Seed Germination?

Seed germination is the fundamental process by which various plant species develop from a single seed into a plant. This process has an impact on crop yield as well as crop quality.

The sprouting of a seedling from an angiosperm or gymnosperm seed is a common example of seed germination.

Seed Germination Procedure

During the early stages of germination, the seeds rapidly absorb water, resulting in swelling and softening of the seed coat at an optimal temperature. Imbibition is the term for this stage. It kicks off the growth process by activating enzymes. The seed’s internal physiology is activated, and it begins to respire, produce proteins, and metabolize the stored food. This is the lag period for seed germination.

The radicle emerges from the seed coat to form a primary root. The seed begins to absorb underground water. After the radicle and plumule emerge, the shoot begins to grow upwards.

The seed cell becomes metabolically active, elongates, and divides in the final stage of seed germination.

The Conditions Required for Seed Germination

Here are some important requirements for a seed to germinate into a seedling and then into a plant.

Water

Water is absolutely necessary for seed germination. Some seeds are extremely dry and require a significant amount of water relative to their dry weight. Water aids in the vital activities of protoplasm by providing necessary hydration, dissolved oxygen for the growing embryo, softening the seed coats, and increasing seed permeability. It also aids in seed rupturing and converts insoluble food into soluble form for translocation to the embryo.

Oxygen

Oxygen is an important and necessary source of energy for seed growth. It is required for metabolism by the germinating seed and is used as part of aerobic respiration until it is able to grow its own green leaves. The pores of soil particles contain oxygen, but if the seed is buried too deeply, it will be deprived of this oxygen.

Temperature

A seed requires a moderate temperature of around 25-30°C to germinate. Different seeds, obviously, require different optimal temperatures. Some seeds require special conditions, such as a lower or higher temperature ranging from 5 to 40°C.

Light or Darkness 

Light or darkness can serve as an environmental cue. Many seeds do not germinate until they are exposed to sunlight.

Under the aforementioned favorable conditions, the seed germination process begins. The embryo rapidly expands and grows in the seeds, rupturing the covering layers and allowing the radicle to emerge. This radical emergence is regarded as the end of germination.

Seed Germination Influencing Factors

There are several important factors that influence seed germination. These are some examples:

External Elements

Water

Seed germination is affected by a lack of or an excess of water.

Temperature 

Temperature has an impact on the seed’s growth rate as well as its metabolism.

A temperature below the moderate level, in some cases, slows seed germination and promotes fungal growth. In some cases, germination stops when the temperature rises above a certain threshold.

Oxygen

 Germinating seeds respire rapidly and release the energy needed for growth. As a result, a lack of oxygen has an impact on seed germination.

Internal Elements

Dormancy 

Dormancy is caused by internal factors.

This is a condition in which seeds are unable to germinate even under ideal conditions.

During the dormancy of seeds:

The seed coat, which is water and gas resistant, limits water uptake and oxygen exchange.

Undeveloped or immature embryo seeds do not germinate.

Plant growth regulators, found in some seeds, prevent seed germination.

Some seeds require more time to germinate.

Frequently Asked Questions on Seed Germination 

What Promotes Seed Germination?

Water, temperature, and oxygen are the three primary factors that control seed germination. In some species, light has a significant impact on germination. As previously stated, adequate water is essential during germination and seedling growth.

What are the three factors required for successful seed germination?

To germinate, all seeds require water, oxygen, and a warm environment. Some seeds, too, require adequate lighting.

What are the four factors that influence seed germination?

Water, light, oxygen, and temperature are the four environmental factors that influence seed germination.

What is the most important germination process?

 The most important stage in a plant’s life cycle is seed germination. Water, oxygen, temperature, and light are all required for the seed germination process, which begins with imbibition and continues through activation and manifestation.