Have you ever thought of what are the Functions of Seed Coat? A small mustard seeds to big coconuts, all of them have seed coats of some kind. They are one of the most essential parts of every seed. The seed coat is the first line of defense for the seed. It creates a dynamic wall to protect the seed from any external factors like wind, water, or sunlight. All of these natural resources are important for plant growth but not good if they reach the seed before time. So it is the function of the seed coat to protect the embryo until it germinates. In simple words, Seed protection is the only function of the seed coat.
Seed coat has another interesting function, especially for dicot seeds. It prevents the cotyledons from splitting before germination. If that happens then the plant will never grow.
What is a Seed Coat?
A Seed coat is the outer covering of a seed. It is a thin protective layer that surrounds the seed. This is the first visible thing that we see in any seed. Some seeds have thin papery coats while others may have thick seed coats.
All of us have seen soaked beans. The bean seed swell in water after 10-12 hours of soaking. Once they are soaked the seed coat starts riping off. We can see the dark papery skin slipping off the seed. Smaller seeds have thinner seed coats and are a little difficult to observe.
The seed coat is a covering that is present in all types of seeds. Only they differ in structure, strength, and thickness. These differences are usually due to the varying shape and sizes of the seeds. Sometimes the growing condition also adds to the genetics that evolves the seed coat formation.
Plants thriving in hot climatic conditions develop seed coat that prevents water loss as well as help the seed sprout out quickly in scarce moisture level. On the other hand, Plants in the humid area develop seed coats according to save the seed from too much moisture until it sprouts.
Altogether seed coat is an essential part of the seed that prevents external damage to the endosperm and embryo of the seed.
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How does the Seed Coat Forms?
The seed coat forms from the outer cellular lining of the ovule inside the ovary of the flowers. The Seed coat starts developing before the actual fertilization of the flower. This means if you open up a flower ovary to observe the ovules of the tiny pre emerged seeds then you may find traces of the seed coat yet to form.
The cells surrounding the ovule become the protective covering. They turn dead by the time a seed matures. The only reason it is there is that the seed needs it for protection.
There can be 3 to 6 distinct layers in the seed coat. These layers develop simultaneously during seed maturity. Some seeds may have 2 outer layers and 3 inner layers in their seed coats. While others may have different layer structuring in their seed coats. These seed coats are not as simple as they appear. They have a purpose to protect the life within the seed.
It all starts with the development of a female or a complete flower with an ovary. The journey of the flower starts as a bud and it evolves into a mature flower. This is the time when the ovary also evolves and becomes ready for the pollination and the fertilization of ova. There can be 1 or many ovules within the ovary of a flower. It depends on the plant type. These Ova are fertilized to form the seed. During this process, the outer cell lining of the ovule became the seed coat. It develops layer by layer simultaneously.
The Seed coat is not a single structure instead it has multiple layers arranged together to create a covering. It acts as a dynamic flexible she’d to prevent any external damage to the seed core. This is the first layer of difference for every seed.
Why Is Seed Coat important for the Seed?
The seed coat is very important for the seed. It is there to prevent any extra damage to the seed core. The delicate embryo within the seed needs to be saved until it’s ready to sprout.
The Seed needs protection from various external factors. The air, water, sun, and insects all can damage a seed easily without any protection. The delicate seed can dry out quickly in direct sunlight. Pest and disease can easily damage the soft endosperm and the delicate seedling inside it. Moisture can lead to rotting if it reaches the immature embryo.
Therefore protection of the seed and the embryo is the prime importance of the seed coat.
What is the Main Function of Seed Coat?
The Protection of seed from external damage is the main function of the seed coat. Situations differ from place to place and from plant to plant. So they develop seed coats accordingly for their sustenance.
The seed coat is the first line of defense for the seed. It prevents the sun and air to dry the delicate soft seed core. Thus protecting the embryo from dying. It also prevents pests and disease attacks by creating a physical barrier to the endosperm or the seed itself.
These are the physical functions of a seed coat once the seed is mature. Although the function of a seed coat starts with the formation of the seed. The outer lining of the ovule forms the seed coat. It keeps the ova intact during the fertilization process. It acts as a container for the individual zygote formation keeping each seed isolated within the fruit structure.
Even on the initial days, the seed coat protects the growing seed from any possible damage. It is a simple yet high-functioning structure within a fruit. The parenchyma cells of the seed coat die before the seed matures. IT stays firm to hold the seed until it’s ready to germinate. Till then the only job of the seed coat is to protect the seed from any external damage.
Preventing Dicots from splitting is one of the important functions of the seed coat. You may like Is it illegal to Send Seeds by Mail?
Can Seeds Grow Without Seed Coat?
Only a few seeds can grow without their seed coat. A seed coat is present to protect it from any damage. If you remove the seeded coat before the seed gets ready to germinate then it may perish. The condition outside the seedcoat is not always for the seed and the embryo within it.
This is the reason why plants thriving in harsh conditions develops strong seed coat. They prepare their seed to withstand all the possible situations it may face. This happens due to natural evolution. Plants collect information about their surroundings and forward it to next-generation creating new traits to adapt accordingly. Hence in a difficult situation, they tend to do whatever is necessary to keep the seeds safe.
Some plants especially those that have strong dicot seeds can grow without seed coats in a controlled environment. Monocot seeds are not so comfortable growing without a seed coat. They usually have less moisture than dicots. Without proper protection, they can dehydrate or break quickly.
You can test this with pea, bean, maize, and paddy seeds. You can germinate and grow pea or beans without their seed coat. It is difficult yet completely possible with little effort and practice. Although you may not succeed using the same with maize, corn, or paddy seed. Once you get the rice out of the paddy it won’t germinate, not properly.
Protecting the seed and all its components is one of the main Functions of Seed Coat. It forms by the outer cell lining of the ovules that turn into a seed after fertilization. Some seeds can germinate and grow without a seed coat although it is not natural for any seed to survive without a seed coat. Protection is an essential aspect of survival. If the seed coat is absent then you have to protect the seed manually until it is ready to protect itself.