The process of seed germination
The correct sequence of the seed germination process is
When a seed germinates, the radicle first breaks through the seed coat and grows downward to form a taproot.
At the same time, the cells of the hypocotyl also grow and elongate accordingly, pushing the embryo or germ together with the cotyledons out of the soil surface, and the embryo protruding out of the soil surface to form stems and leaves. The cotyledons extend out of the soil with the embryo, and turn green after unfolding, for photosynthesis, such as cotton and rape.
When the young leaves of the embryo expand to perform photosynthesis, the cotyledons wither and fall off. At this point, a young plant that can live independently has all grown up, which is a seedling.
Expansion of information: Seed germination refers to a series of orderly physiological and morphological processes of seeds starting from imbibition. The germination of seeds requires the right temperature, the right amount of moisture, and sufficient air.
When seeds germinate, they first absorb water. After the seed is soaked in water, the seed coat will swell and soften, allowing more oxygen to pass through the seed coat and enter the inside of the seed. At the same time, carbon dioxide will be discharged through the seed coat, and the physical state inside will change. The second is air, which is carried out during the germination process of the seed. A series of complex life activities, only the seeds continue to breathe, get energy, can ensure the normal progress of life activities; the last is the temperature, the temperature is too low, the respiration is inhibited, the decomposition of nutrients in the seeds and a series of other physiological Activities need to be carried out at a suitable temperature.
The four processes of seed germination
The seed germination process is divided into four stages: imbibition, germination, germination and seedling formation.
(1) Imbibition: It is the initial stage of seed germination. It shows that the seeds swell up to a certain degree of saturation by absorbing water. Rice seeds swell up and the husk becomes soft.
(2) Germination: This is the second stage of seed germination. It is manifested as various weight changes in the seed body. The storage material transforms and transfers to the growth point, so that the volume of the embryo expands, and the tip of the radicle breaks through the seed coat. This phenomenon is called seed germination, also known as “lubai” or “Broken Chest”.
(3) Germination: After the seed germinates, the seed embryo continues to grow. When the radicle and embryo protrude from the seed coat and develop to a certain extent, it is called germination.
(4) Seedling growth: After seeding, the radicle root is pierced down and the coleoptile rises up, and the growth is called rooting and supporting leaves. Subsequently, the incomplete leaves extend out of the sprouts, which is called emergence (also called present green). After the first 1-3 leaves are drawn out, several adventitious roots will grow on the coleoptile nodes, which is good for the seedlings to take root and establish seedlings.
- Although the seeds are mature after they are formed, they often cannot germinate immediately even under suitable environmental conditions. They must go through a relatively static stage before they can germinate. This property of seeds is called dormancy. The dormant seeds are in a state of very slow and almost inactive metabolism.
- The length of seed dormancy period is different. Some plant seeds have a long dormancy period, which takes several weeks or even months or years, and some plants can germinate quickly under suitable environmental conditions after they mature. There is no need to go through a period of dormancy, only those in unfavorable environmental conditions. Under the circumstances, it enters the dormant state.
- Seed dormancy is a phenomenon in which viable seeds cannot germinate under suitable environmental conditions due to internal reasons. Dormancy is a kind of adaptability that plants acquire during long-term system development to resist bad environment, and it is an effective method to regulate the best time and space distribution of seed germination.
- The seeds of crops with dormancy characteristics can prevent ears from germinating in hot and rainy areas; the seeds of some desert plants can be dormant through the dry season to wait for suitable germination conditions.
Seed germination process
The process of seed germination:
During the germination process, the seeds absorb water first, the volume swells, and the seed coat bursts.
At the same time, the life activities in the embryo become active and begin to divide and grow after getting nutrients and energy:
The radicle elongates to protrude the seed coat and develop into roots,
Soon, some fine roots grew from around this root;
At this time, the hypocotyl below midnight is also extending, bending and arching out of the ground,
When the hypocotyl is straightened, the top will bring two cotyledons out of the soil, which is unearthed by the seedlings.
The embryo gradually develops into a stem, and leaves on the stem, which gradually turn green in the sun, and the seedling can live independently.
After some seeds germinate, when the seedlings are unearthed, the cotyledons should be planted shallowly; the hypocotyls below the cotyledons cannot be elongated when the seeds germinate, and they stay in the soil at midnight without sticking out of the soil, so they should be planted Go deeper.