Key Points of Angelica sinensis Propagation Techniques and Detailed Explanation of Seedling Methods
Angelica sinensis is propagated by seed, generally using the method of raising seedlings and transplanting, though direct sowing can also be used.
1. Seedling raising and transplanting
(1) Seed selection: After seed selection, Angelica sinensis yields about 14.6 kg more per mu than unselected seeds. The main selection method is ear selection. At harvest time, when the seed coat turns sky blue or pink and the flowering stem droops, select fruit ears that have the characteristics of this variety, grow well and vigorously, are free of pests and diseases, and are highly mature; cut them off together with the flowering stem, dry them in a ventilated and dry place, thresh, and store for later use. Because Angelica sinensis seeds do not mature uniformly, seed collection must be carried out in batches, cutting one ear as it matures, and removing moldy, mixed, shriveled seeds and those damaged by pests and diseases. Use plump, well-filled seeds for planting, and never harvest whole plants or entire plots at once. To ensure seed quality, a germination test should also be done before sowing.
(2) Pre-sowing treatment: To make seeds germinate quickly and emerge uniformly after sowing, seed soaking treatment is often carried out before sowing in production, so that the seed coat absorbs water and softens in a short time, increasing permeability and promoting seed germination. The seed treatment method for Angelica sinensis is to soak the seeds in warm water at 25-30°C for 24 hours, take them out and dry them, then mix them with plant ash at a ratio of 1:10.
(3) Sowing time: The suitable sowing period should be determined according to local altitude, temperature and other conditions, and it should not be too early or too late. If too early, premature bolting is likely to occur; if too late, the seedlings are too small, have poor stress resistance, and the survival rate is low. In low-temperature, high-altitude areas, sowing should be done in early to mid-June; in slightly warmer, low-altitude areas, sowing should be done from mid-July to early August. Regardless of whether sowing is early or late, when raising seedlings it is necessary to ensure that the seedling age does not exceed 110 days and that the weight of 100 seedlings does not exceed 40 g.
(4) Sowing method: Broadcast sowing is generally used for raising seedlings, though drilling can also be used. For broadcast sowing, scatter the seeds evenly on the seedbed, cover with a layer of fine fertile soil about 0.5-1.0 cm thick, and then cover with about 3-5 cm of dry straw to preserve warmth and moisture. In places with little rainfall, sowing is best done before rain so that seedlings emerge uniformly and vigorously. For drilling, open horizontal furrows at a row spacing of 20 cm and a furrow depth of 3-5 cm. When sowing, scatter the seeds evenly in the furrows, cover with fine soil until the seeds are no longer visible, and then cover the bed with dry straw or set up a shed for shade.
(5) Sowing rate: The yield per unit area of Angelica sinensis is composed of the number of plants and the root weight per plant. The amount sown and whether sowing is uniform will affect the later growth and yield of the planted plants. If the sowing rate is too small, although growth is fast and roots are large and heavy, large seedlings and forked seedlings are easily formed, and premature bolting is likely after transplanting. If the sowing rate is too large, small and weak seedlings are easily formed, the survival rate after transplanting is low, and planting costs increase. In production, the seed rate is about 4-5 kg per mu for broadcast sowing and about 4 kg for drilling.
(6) Seedling stage management: To increase the seed germination rate and achieve uniform and strong seedlings, the seedbed after sowing must be kept moist, while also covering with grass to preserve moisture. After sowing, seedlings generally emerge in 15-20 days. If the soil is moist and the temperature is suitable, seedlings can emerge in 7-8 days. Newly emerged seedlings are easily killed by strong sunlight, so the covering grass should be loosened to shade the seedlings. After 1 month, when the seedlings grow to a height of 1-2 cm, part of the covering grass on the bed surface should be removed. After removing the grass, set up a shed or use black netting for shade, with a height of about 60 cm, and control the shading degree to 1/3-1/2 of full sunlight. Remove the shading material after the dog days.
When the seedlings grow 3 true leaves and reach a height of 3 cm, the first loosening of the soil and thinning can be carried out, removing weak and diseased seedlings and maintaining a plant spacing of about 1 cm. Remove weeds in the field at any time.
To prevent excessive seedling growth and the formation of large seedlings that bolt early after transplanting, topdressing is generally not suitable during the seedling stage. Only in the later stage of seedling growth should human manure and urine or an appropriate amount of ammonium bicarbonate be applied as topdressing.
(7) Digging up seedlings and storage: Seedlings are not suitable for overwintering in the open field, because seedlings overwintering in the open field have poor drought resistance and a high bolting rate after vernalization in the field, so the seedlings should be dug up and stored before the ground freezes. The suitable time for digging up seedlings is when the temperature drops to about 5°C and the aboveground leaves begin to turn yellow and wither. In Gansu production areas, this is generally around Cold Dew. In Sichuan production areas, it is around Frost's Descent. Seedlings should be dug up on sunny days to prevent rain from causing root rot. When digging up seedlings, use a small shovel to dig them out, pull out the seedlings, and strive to keep the root system intact. Damaging the buds and root body is strictly prohibited. Then shake off the soil, cut off the leaves while retaining a 1 cm long petiole, remove diseased, damaged, injured and rotting seedlings, divide them into large, medium and small grades, tie every 100 plants into a bundle, place them on dry raw soil in a cool, dry place and air-dry for 5-7 days, so that the outer skin of the fresh seedlings dries slightly, the root body begins to soften (water content 60-65%), and the petioles shrink, after which they can be stored. Never air-dry for too long, as the seedlings will lose too much water. There are two storage methods: pit storage and dry storage. Dry storage has the strongest drought resistance, while pit storage has weaker drought resistance. If conditions permit, frozen storage below 0°C is best.
Dry storage is also called heap storage. In a smokeless, windproof room, build a square pit 100 cm long and 100 cm wide with dry adobe bricks, spread a layer of soil on the bottom of the pit, then place the seedlings layer by layer from the center outward, with the tails toward the center and the heads outward. For the outermost ring of each layer, leave a 6 cm wide gap between the seedling heads and the pit wall. In this way, one layer of seedlings and one layer of soil, fill the pit, and finally cover with a layer of thick soil, with the top shaped like a fish back. It is also possible not to build a pit, but to store layer by layer on the ground and finally cover with soil in a steamed bun shape. If the number of seedlings is small, baskets can also be used for stratified storage.
For pit storage, choose a dry, cool place with no rat holes and no water seepage to dig the pit. The size of the pit depends on the number of seedlings, and the shape can be rectangular or round. First spread a layer of raw soil with suitable moisture, about 3 cm thick, on the bottom of the pit, then place a layer of seedlings, spread a layer of soil, and store 6-7 layers in this way, with a height of about 65-75 cm. Finally, cover the top with soil higher than the ground to prevent water accumulation from causing rot. When placing seedlings, alternate heads and tails and arrange them neatly.
(8) Transplanting: In order to reduce the bolting rate, seedlings used for planting must be strictly selected. Generally, it is required that the seedling roots be intact, free of pests and diseases, with straight roots and few forked roots, and 3-5 mm thick. Seedlings that are too large are prone to bolting, while seedlings that are too small are too weak and grow poorly. In Angelica sinensis production, spring planting is mostly used. Because altitude, temperature and other conditions vary from place to place, transplanting time differs. Spring temperatures are unstable. If transplanting is too early, seedlings may be killed by late frost after emergence; if transplanting is too late, the seedlings have already sprouted, later development is poor, and the seedlings are easily damaged, affecting survival. Generally, it starts after Clear and Bright and ends before Grain Rain.
In recent years, Minxian County, Gansu, has changed spring planting to winter planting. After several years of experiments, high yields have been obtained, increasing yield by more than 10% compared with spring planting. That is: transplant the seedlings raised that year into the field from Cold Dew to Frost's Descent, and harvest them together with spring-planted Angelica sinensis in the autumn of the following year. The advantages of winter planting are stable roots and strong seedlings, earlier green-up the following year, and reduced losses from disease infection and mold during winter storage.
Transplanting methods differ from place to place. In Sichuan production areas, holes are dug on the bed to plant seedlings, with a hole spacing of 30 cm and a row spacing of 36 cm, planting 2-3 seedlings per hole, requiring 10,000-15,000 seedlings per mu. When planting, the roots should be spread out and not bent. After slightly filling with soil and pressing firmly, apply barnyard manure, about 750 kg per mu, and then cover the root heads with fine soil to a depth of 3 cm to prevent late frost damage. Minxian County, Gansu, uses hole planting or furrow planting. Hole planting means digging holes in a triangular staggered pattern on the prepared land according to a plant-row spacing of 24 x 33 (cm2), with a hole depth of 18-21 cm and a hole diameter of 12-15 cm, about 6,000-8,000 holes per mu, placing one large, one medium and one small seedling in each hole, generally requiring 15-20 kg of clean seedlings per mu. Place the seedlings vertically in the holes and cover with soil. Covering with soil higher than the ground is called "bright hole", mostly used on land with loose soil layers and finely prepared soil. Planting seedlings along the slope, with root heads outward and root tails inward placed flat in the hole, is called "upturned hole", mostly used on sloping land, which helps maintain soil moisture and prevents root heads from being exposed on the soil surface after rain. After transplanting, cover with 2-3 cm of soil and press lightly. Furrow planting means opening horizontal furrows on the prepared bed surface, with a furrow spacing of 40 cm and a depth of 15 cm, placing large, medium and small seedlings alternately in the furrows at a plant spacing of 3-5 cm, with the rhizome 2 cm below the bed surface, and covering with 2-3 cm of soil.
To make Angelica sinensis develop uniformly, some spare seedlings should be planted at the field edge or beside the bed at the same time as transplanting, in order to fill gaps where seedlings are missing.
2. Direct sowing
In order to prevent early bolting of Angelica sinensis, cultivation scientists have conducted a great deal of research, changing summer seedling raising and transplanting to autumn direct sowing and controlling seedling size. This not only prevents early bolting, but also reduces procedures such as seedling raising, seedling digging, seedling storage and seedling planting, saves labor, and reforms cultivation techniques. According to the experimental results of different sowing dates conducted by the Northwest Institute of Botany in 1975, autumn sowing can effectively prevent early bolting. However, the time of autumn sowing must be controlled, and sowing must be done around Start of Autumn. If too early, the purpose of preventing bolting cannot be achieved; if too late, the seedlings have poor resistance. In short, it should be ensured that the seedlings of that year have a growth period of about 70 days, grow 3-4 true leaves, and have a root diameter of about 0.2 cm before they can overwinter safely. In places with high altitude and low temperature, sow in early August; in places with low altitude and high temperature, sowing can be delayed to mid-August to early September.
Because direct sowing cultivation does not have the problem of early bolting, it is advisable to choose old, plump "huoyaozi" seeds for planting. This kind of seed has sufficient nutrition and strong vitality, and after sowing, seedlings emerge quickly, uniformly and grow vigorously. In addition, the single root weight of direct sowing is slightly lower than that of seedling raising and transplanting, so production generally relies on increasing population density to increase yield. At the same time, because its growth cycle is short, in order to obtain high yield, in addition to applying sufficient base fertilizer, topdressing should also be done in time. Apply more nitrogen fertilizer during the seedling stage, and apply phosphorus and potassium fertilizer early after the seedlings are established.
For direct sowing land, choose plots facing the sun, with gentle slope and lower altitude, requiring deep soil layers and fertile, loose soil rich in organic matter. Direct sowing methods are divided into hole sowing and drilling, with hole sowing being better. For hole sowing, open holes on the bed in a plum blossom pattern at a hole spacing of 27 cm, 3-5 cm deep, with a flat hole bottom, sowing about 10 seeds per hole and spreading them radially. For drilling, open horizontal furrows on the prepared bed surface, 5 cm deep, with a furrow spacing of 30 cm, and scatter seeds evenly in the furrows. Whether drilling or hole sowing, lightly tread on the furrows or holes with the foot and press slightly so that the seeds are in close contact with the soil, then cover with fine fertile soil about 1 cm thick, rake the bed surface level, and cover with a layer of short grass or fallen leaves to help retain moisture. Usually, the seed rate per mu is 0.75-1 kg for hole sowing and 1.5-2 kg for drilling.
Direct-sown Angelica sinensis seedlings overwinter in the field and are prone to frost damage, so some measures must be taken to protect the seedlings, such as covering the seedlings with manure and soil in combination with topdressing before winter, and watering in winter to prevent freezing.