Biological Characteristics of Angelica sinensis (Ⅰ)

Angelica seeds lost their germination rate when stored at room temperature for 1 year, and could be stored for more than 3 years under the condition of low temperature and drying. Mature seeds can germinate and grow under suitable conditions such as moisture, temperature and oxygen. Seed germination goes through three processes:

The main results are as follows: (1) the components of Angelica seeds such as starch, fat, protein and cellulose in the process of water absorption and expansion are hydrophilic colloids, which are in the state of gel under dry conditions, and when the seed absorbs water, the water permeates into the colloid network structure inside the seed. The gel state becomes a sol state, and the volume increases accordingly. This process belongs to the physical and chemical phenomenon, which is called the seed water absorption expansion process.

(2) in the process of material transformation, with the increase of seed water absorption, the activity of various enzymes is enhanced, and the respiratory activity is also carried out vigorously. Under the action of enzymes, the complex substances in the seeds (starch, protein, fat and cellulose, etc.) are hydrolyzed into soluble simple substances that are easy to be absorbed by embryos, such as monosaccharides, amino acids, etc., which are the energy and material sources of seed germination. The above changes in seed contents promote embryo germination, which is a biochemical phenomenon called seed material transformation.

(3) in the biological process, when the seed absorbs water up to about 45% of its own weight, the water absorption expansion ends, the seed contents are transformed, and then the seed begins to germinate and grow. First, the radicle begins to elongate and break through the seed coat, then the coleoptile breaks out, and then one or two pairs of seed roots grow. In general, the radicle grows faster than the germ. When the germ reaches half the length of the seed, and the radicle is as long as the seed, it is called germination.

After the seeds germinate, the radicle elongates rapidly and bends downward to grow into the soil. At the same time, the Hypocotyl elongates, causing the curved cotyledons to break the topsoil with the pericarp and protrude from the ground. Two long lanceolate cotyledons spread out to form seedlings. When the cotyledon grows to about 2 cm long, the first primary leaf grows from the center of the cotyledon. Seed germination and emergence are not only related to seed quality, but also closely related to external conditions.

Moisture: when seeds germinate, all physiological changes must be attended by water, but if the soil moisture is too much, there is not enough oxygen, which is not conducive to Angelica sinensis germination, or even cause seed rot, even if the emergence and growth is very weak, so when Gui sowing, the soil water content is required to be kept at 22-28%. In order to make Angelica seeds germinate quickly and emerge evenly, seed soaking treatment is generally carried out before sowing, so that the seed water content is about 40%.

Temperature: the lowest temperature for germination of Angelica sinensis seeds is 6 ℃, the optimum temperature is about 20 ℃, and the highest temperature is 34-36 ℃. In a certain range, the rate of seed germination increased with the increase of temperature, but after 24 ℃, the germination process was inhibited due to the increase of respiratory intensity, and when it was less than 10 ℃, the germination was slow and irregular, and it was easy to be infected with diseases. Generally speaking, it is beneficial to cultivate strong seedlings when the daily average temperature is about 16 ℃. Under the condition of normal sowing time, it takes about 10-16 days from sowing to emergence, daily average temperature 10: 12 ℃ sowing, 16-20 days emergence, daily average temperature 20-24 ℃, 7-14 days after sowing.

Oxygen: Angelica seeds breathe very vigorously when they germinate, need enough oxygen, the soil is heavy, the soil moisture is too high, hardened, sown too deep, the seeds can not germinate due to lack of oxygen, or even rot, even if the emergence and growth is very weak.