The whole process of plant germination includes five processes: seed imbibition, hydration and enzyme activation, cell division and enlargement, embryo breaking through the seed coat, and growing into seedlings.

1. Swelling

Swelling occurs when the seeds are immersed in water or dropped into moist soil. The hydrophilic substances in them attract water molecules, causing the seed volume to increase rapidly. Large (sometimes can be increased by more than 1 times). The water absorption is rapid at the beginning and then gradually slows down.

When the seeds swell, they will have great force and can even break the glass bottle. As a result of the imbibition, the seed coat becomes soft or cracked, the permeability of the seed coat to gases, etc. increases, and germination begins.

2. Hydration and enzyme activation

After the imbibition is basically completed, the cell wall and protoplasm of the seed cells are hydrated, and the protoplasm changes from a gel state to a sol state. Various enzymes begin to activate, and respiration and metabolism increase dramatically.

3. Cell division and enlargement

When cells divide and enlarge, the amount of water absorbed increases rapidly, the embryo begins to grow, and the nutrients stored in the seed begin to be consumed in large quantities.

4. The embryo breaks through the seed coat

When the embryo breaks through the seed coat, the size of the embryo increases after growth and breaks through the seed coat and is exposed. Most seeds emerge first from the radicle and then the embryo.

5. Grow into seedlings

The embryo grows roots, stems, and leaves to form seedlings. The hypocotyl of some seeds does not elongate, and the cotyledons remain in the soil. Only the epicotyl and embryo grow out of the soil surface to form seedlings. These seedlings are called cotyledon-retaining soil seedlings, such as peas, broad beans, etc. When the seeds of some plants, such as cotton, rape, melons, and beans, germinate, the hypocotyls elongate and push the cotyledons out of the soil, forming seedlings with cotyledons emerging from the soil.

Extended information

Methods to solve the problem of difficulty in germination of plant seeds

1. Drying the seeds

One week before soaking the seeds, choose a sunny day and dry the seeds for 6 -8 hours, and then place the sun-dried seeds in a dry, cool place to cool down to promote the respiration and enzyme activity of the seeds, which is beneficial to improving the germination rate and germination potential of the seeds; sun-drying the seeds can also kill some of the attached seeds. Pathogens on seed shells.

Do not dry seeds on cement ground. On the one hand, it may cause the seeds to lose too much water and peel off. On the other hand, it may cause the seeds to be scalded.

2. Seed selection

It is required to use clean water to select seeds, fish out the grains floating on the surface, soak the seeds separately for germination and save them for later use. Select plump seeds to cultivate Neat and healthy seedlings emerge.

3. Promote seed soaking in running water

The soaking time should not be too long. It is best to use the method of "soaking in the day and dew at night", that is, soaking the seeds during the day and taking them out and spreading them out at night. It is best to soak the seeds during the day. Soak the seeds in flowing water for 8 hours or in a water tank (change the water every 8 hours). The specific seed soaking time depends on the air temperature and water temperature, and the seeds have to absorb enough water.

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