Germination

The procedure by which a seed grows into a plant refers to the germination process. The formation of a sporeling from a spore and a seed sprouting to form a seedling are well-known forms of germination. The germination process keeps some seedlings safe from eruptions of bad weather. Viable seeds should contain healthy embryonic tissue to germinate. Apart from it, the factors like availability of oxygen, water absorption, warming, exposure to light, and passage of time affect this process. However, not all seeds have the same temperature and light requirements. Read out the article below to know the complete process of plant germination along with necessary conditions and factors affecting it. 

What is Seed Germination?

The fundamental process by which different species of plant grow from a single seed into a young plant describes the process of seed germination. It is of two kinds:

• Epigeal Seed Germination: Due to the extension of the hypocotyl, the cotyledons come above the surface of the soil. The seeds like bean, papaya, onion, gourd, cotton and castor fall under this category. Besides food storage, cotyledons in these seeds perform the process of photosynthesis till the seedling becomes self-regulating. In some cases, like the bean, cotyledons are thick and thus do not develop leaf-like. When seedling consumes their food reserves, cotyledons contract and falls off.

• Hypogeal Seed Germination: The cotyledons do not come out of the soil surface in this category. Seeds of maize, rice, pea, gram, mango, and groundnut fall under this type. The part of the embryonic axis between cotyledons and plumule that refers to epicotyl stretches. It results in pushing the shoot out of the soil. In this way, plumules grow upward and the leaves come out. 

Stages of Seed Germination

• Environmental Conditions: 

The environmental conditions must be favorable to initiate the process. The critical conditions involve the amount of water, oxygen, soil depth, and temperature to support the growth of the plant. Moist and warm soil conditions are vital for the process to occur.

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The above picture shows the growth of a plant from a seed and describes the process of seed germination.

• Water Imbibition: 

The simple answer to the question of what is germination is that the term refers to the beginning of seed growth. When environmental conditions are optimum, water imbibition begins the process of seed sprouting. The seeds take up water speedily through the micropyle structure. It results in softening of the seed coat, and it starts swelling until the opening of splits. It also refers to the lag phase of seed sprouting in which the seed stimulates its internal physiology. It begins to respire and produce proteins. 

• Root and Shoot Growth:

It is one of the crucial stages of germination in which the seed begins absorbing underground water. The radicle emerges to form a primary root, and the plumule forms a shoot by rupturing the seed coat. The activated enzymes are responsible for initiating this process. The shoot grows upwards towards the surface of the soil, and the root grows downwards.

• Formation of Seedling: 

The cotyledons expand and become unfolded when the shoot emerges from the soil surface. It results in the formation of the first leaves. Now the plant is ready to instigate the process of photosynthesis.

Conditions Required for Bean Germination

• Oxygen: For the proper growth of beans, oxygen plays a vital role. The germinating seed requires oxygen for metabolism. It is used as a part of aerobic respiration until the seed manages to grow leaves. It can be found in the soil particles' pores. However, if the bean is buried in-depth, then it might get deprived of oxygen.

• Water: The term seed sprouting describes the process of seed germination. Water is an essential requirement to initiate this process. Some seeds are dry and require the intake of a significant amount of water. It helps in providing dissolved oxygen for the growing bean embryo and necessary hydration for the critical activities of protoplasm. It not only softens the seed coats but also enhances the seed permeability.

• Temperature: Different seeds need different optimal temperatures. Generally, it requires a moderate temperature of 25 to 30-degree Celsius for a bean to germinate. Some seeds may require a low temperature of about 5-degree Celsius, and some may require a higher temperature of about 40- degrees Celsius.

Apart from these conditions, some beans might not germinate until sunlight falls on them. Thus, germination definition refers to the formation of a seedling or sporeling under suitable environmental conditions. 

The growth of a seed into a plant is the answer to what is the process of germination. Seeds require ideal amounts of oxygen and water to germinate. If any of the essential environmental conditions required fail to meet then it will lead to slow and uneven growth of plants.