What and how are bean seeds formed?
Humanity has been cultivating beans for about five thousand years. However, this culture came to Europe and Russia only in the eighteenth century. The seeds and pods of beans, rich in proteins, carbohydrates and vitamins, are eaten.
This useful and beautiful plant is easy to grow in your garden. To understand the nuances of caring for beans, let’s get acquainted with the structural features and germination pattern of bean seeds.
What are bean seeds?
The legume family, which includes beans, belongs to the class of dicotyledonous plants.
Beans are an annual herbaceous, self-pollinating plant. Depending on the variety, bush, semi-climbing and climbing forms are distinguished.
The peculiarity of the structure of the bean root system is that nodules containing nitrogen-fixing bacteria are formed on the root shoots. Symbiosis with such bacteria helps plants absorb free nitrogen. The taproot penetrates deep into the soil up to 1 m.
Dry bivalve fruits are called beans or pods. They contain several kidney-shaped white, red or variegated seeds. Their sizes vary from 8 to 25 mm.
Interesting. Beans have significant nutritional value. The amino acids of the plant are similar in composition to the proteins of meat and fish. The product contains vitamins, mainly group B, and minerals (potassium, calcium, magnesium, phosphorus). Most of the beneficial substances are preserved during preservation and heat treatment.
Seed structures with photos and their meaning
The seed is formed after fertilization from the ovule and carries the embryo. The embryo contains two cotyledons or embryonic leaves, an embryonic root and an embryonic shoot. The skin protects the embryo from drying out and damage. Let's take a closer look at the structure of the bean seed embryo.
Embryonic shoot of a dicotyledonous plant
The embryonic shoot consists of a subcotyledon (hypocotyl) and a bud.
The bud has a growth cone and several leaf primordia. The main shoot of the plant develops from these organs.
The subcotyledonous knee is located between the cotyledonous node, from which the cotyledons extend, and the embryonic root. It looks like a stalk.
Under favorable conditions, the hypocotyl begins to grow first and pushes the embryonic root out of the seed. Then, actively developing in length, it bends in an arc and appears on the soil surface. Afterwards, the sprout straightens and produces cotyledons and an embryonic bud.
Germinal root
The embryonic root consists of a cluster of cells capable of intensive division, covered with a root cap. It is the first to appear outside the seed, anchors itself in the soil and begins to absorb moisture and nutrients.
The main (first order) root develops from the embryonic root. As a result of the branching of the main root, the bean develops a taproot perennial root system.
Cotyledons
During the ripening process of the seed, the nutrients necessary for the development of the sprout accumulate in the cotyledons. After appearing on the soil surface, the embryonic leaves turn green and begin photosynthesis, ensuring the growth of the main shoot from the embryonic bud.
When the first leaves develop sufficiently, the cotyledons dry out and fall off.
What is seed germination
Ripe seeds remain dormant and can remain in unfavorable conditions for a long time, keeping the embryo alive.
The transition from dormancy to life activity is called germination. In the embryo, metabolic processes accelerate and the seeds swell. The root appears first, then the hypocotyl. During germination, the embryo develops using nutrients from the seed.
Conditions required for germination
For germination, a set of conditions is required: a living embryo, favorable temperature and humidity, suitable light conditions and access to oxygen.
Temperature
Germination is possible only at positive temperatures. The temperature range favorable for the emergence of sprouts varies for plants of different groups and geographical origin.
For beans, the minimum germination temperature is +8 - +10°C, the optimal temperature is +20 - +22°C.
Humidity
Seed activation begins with good moisture. Water enhances respiration and initiates the work of enzymes, under the influence of which accumulated nutrients are converted into digestible form.
Fats are converted into fatty acids, starches into sugars, and proteins into amino acids. Protein-rich seeds such as beans and peas need the most water to germinate.
Oxygen
Active metabolism necessary for growth requires oxygen. This element is involved in synthesis reactions inside cells.
Without access to air, the seed will not be able to germinate; it will die in dense soil or under a layer of water.
Light mode
Sunlight is necessary for photosynthesis reactions - the formation of nutrients. If there is insufficient lighting, the seedling lags behind in development or stops growing altogether.
Beans are demanding on light intensity, so they are planted in open, not shaded areas.
Read also:
What are the benefits of bean sprouts, how to sprout them correctly and cook them deliciously.
Conclusion
Inside the fruit (bean) there are from 2 to 8 beans. The seeds are kidney-shaped and colored, depending on the variety, red, white, or black. The size ranges from 8 to 25 mm. Like any seed of a dicotyledonous plant, the bean consists of two cotyledons filled with nutrients and an embryo. The dense seed coat provides protection from damage.
For bean seeds to germinate, a combination of favorable factors is necessary: temperature not lower than +10°C, high humidity, access to oxygen and intense lighting. Bean seeds remain viable for 5-6 years. With proper germination and care, beans will delight you with a rich harvest of nutritious, healthy and tasty beans.