The seed is the undeveloped plant embryo and is enclosed in a protective outer covering. It is the food reserve of the plant and is stored in a place where it can be easily harvested. A seed may be a tuber, a husk, or anything else that can be sown.
Embryonic tissue
Seeds are small plants that resemble miniature versions of the mother plant. They are typically composed of embryo, endosperm, and a coat. The seed may be accompanied by a handful of perisperm and other appendages. It is also capable of performing various functions like dispersal, multiplication, and perennation.
As one might expect, the main function of the seed is to store food for the seedling. However, its other role is to protect the embryo from mechanical injury. For this reason, a seed coat is a valuable asset. A mature coat can be a paper-thin layer in peanuts, or thick as a hard shell in honey locust. In other words, the seed coat explains the functions of the other three components of the seed.
Endosperm is a rich source of starch, oil, and protein. This makes it a rich nutrient-storing tissue. Besides, it is highly mobile and can be absorbed by the embryo. On the other hand, the perisperm is a less obvious entity.
Structure
Seeds are an important component of flowering plants. They have three major structures: cotyledons, endosperm, and seed coat. Each has its own unique structure and shape. The endosperm stores food for the developing seedling. In the early stages of development, the endosperm contains food reserves to fuel the growth of the embryo. During this period, a thick seed coat prevents the loss of water, protects the seed from water-borne parasites, and keeps it dry.
Seeds are classified into two groups: monocotyledonous and dicotyledonous. Monocotyledonous seeds have only one cotyledon, while dicotyledonous seeds have two. Exalbuminous seeds lack endosperm and have membranous cotyledons.
The external morphology of seeds has been studied for a large number of genera. It has been used to establish evolutionary relationships and solve classification problems. Many of these patterns have been used as genetic markers for breeding and genotyping hybrid progenies.
The most important structural component of a seed is the testa. This outer layer of the seed coat protects the internal parts of the seed from dessication, bacteria, insects, and sunlight.
Germination
The process of seed germination is a complex multi-stage development that involves the activation of several metabolic activities. In the initial stages, the seed takes up water through its micropyle. It then starts to absorb oxygen, which is required for the metabolism during germination.
After germination, a radicle is protruded from the seed coat and the seed begins to grow. As the embryo develops, it grows into a plant and bears flowers.
The seed’s germination depends on environmental conditions. It needs adequate light and water to survive.
When a seed is sown in moist soil, it begins to take up water and oxygen. During germination, the seed coat breaks and the radicle or coleoptile emerges. This protrusion is accompanied by the formation of the primary root.
Seed germination is regulated by internal and external factors. Plant hormones, including plan hormones, are important in the regulation of germination. These hormones act to control the rupturing of the testa and endosperm. They also inhibit germination by promoting dormancy.
Oils and stimulants
Industrial seed oils are used to make many of the packaged foods we eat. They add texture and taste to some foods, but they can also be dangerous.
The industrial process for making these oils involves high temperatures and mechanical pressure. This process breaks down the fats in the seeds. Once refined, these oils are often high in inflammatory linoleic acid, a polyunsaturated fatty acid that can lead to disease.
In the last century, increased vegetable oil consumption has been associated with increased rates of heart disease, diabetes, and cancer. It has been estimated that people living in industrialized countries consume about 20% of their calories from seed oils rich in linoleic acid.
In the past two decades, vegetable oil production has grown 16-fold. Today, it is estimated that over 30% of the world’s total oil production comes from vegetable oils.
Despite the popularity of industrial seed oils, their health benefits have not been well studied. Studies conducted in the 1960s and 1970s had a tendency to downplay their potential harm.
