vegetative propagation
Some organs of higher plants can redifferentiate and develop into complete plants after leaving the mother's body, which is called plant regeneration. Vegetative reproduction is a kind of reproduction method that uses the regenerative ability of plant vegetative organs to reproduce new individuals.
The offspring of asexual reproduction come from the vegetative body of the same plant, and their individual development is not a new beginning, but a continuation of maternal development. Therefore, early flowering and early fruiting can maintain the excellent characters and characteristics of the mother. However, the reproductive coefficient of asexual reproduction is low, and some varieties, such as Rehmannia glutinosa and Dioscorea opposita, are prone to variety degradation if they are propagated for a long time.
Commonly used asexual reproduction methods are as follows:
Isolation breeding
Breeding method of separating and culturing vegetative organs of plants into independent new individuals. The method is simple and has high survival rate. The separation period varies with the species of medicinal plants and climate, and is usually carried out in the dormant period of plants in late autumn or early spring. According to the different parts of the mother plant, it can be divided into daughter bulbs (such as saffron), daughter blocks (such as yam and bletilla striata), daughter roots (such as salvia miltiorrhiza and aster) and daughter plants (such as Amomum villosum and Ophiopogon japonicus).
Stratified propagation
Bury the branches or vines of the mother plant in the soil, or wrap the branches with soil and moss. Let them take root, and then cut them from the mother plant to become independent plants. Layering methods include common layering method, wave layering method, pile soil layering method and air layering method. Aristolochia, Rose, Polygonum Multiflori Radix, Fructus Viticis, Fructus Forsythiae, etc. Can be spread in this way.
cutting
A part of a plant's vegetative organs, such as roots, stems, leaves, etc. Cut and insert into the substrate under suitable conditions, so that they can take root or sprout, and use their functional ability or regeneration ability to become new plants. Usually, cutting with woody plant branches (except those that are not lignified) is called hard branch cutting, and cutting with woody plant branches and non-lignified herbs is called blank cutting.
(1) Cutting period The cutting period in the open field varies with plant species, characteristics and climate. Herbs have strong adaptability, and the cutting time is not strict, except in cold and summer. Dormancy period is generally suitable for woody plants; Evergreen plants are suitable for cutting in summer with high temperature and humidity.
(2) Methods to promote cuttings to take root.
A. Mechanically treat plants that are difficult to survive by cutting. Choose branches in advance during the growth period, and take measures such as ring cutting, cutting and strangulation to make nutrients accumulate near the wound, and then cut branches to promote rooting.
B. Clove, carnation and other cuttings were treated with chemicals, and the lower end was soaked in 5% ~ 10% sucrose solution for 24 hours, and then cut, with remarkable effect.
C growth regulators are usually used to treat drilling cuttings, such as naphthylacetic acid, 2,4-d, indoleacetic acid, etc. It can significantly shorten the rooting time of cuttings, induce cuttings with difficulty in rooting and improve the survival rate. If 0.1%2,4-d powder is used to treat the cuttings of Fructus Aurantii, the rooting rate can reach 100%.
③ Drill cuttings are widely used in production. Woody plants choose biennial branches, and herbs use young branches as cuttings. When cutting, select branches and cut them into small segments of 10 ~ 20cm, with the upper segment slightly inclined above the bud and the lower segment slightly inclined below the node, and each segment should have 2 ~ 3 buds. Except the top of the cutting 1 ~ 2 leaves (only half of the big leaves are left), all the other leaves are removed. Then insert it into the seedbed, the exposed soil surface at the upper end is about 1/4 ~ 1/3 of the cutting, shade it, water it frequently, keep it moist, and transplant it after survival.
propagation by grafting
Grafting propagation refers to the propagation method of grafting branches or buds of one plant to another rooted plant, so that the plants can heal and grow into new independent individuals. Branches or buds used for grafting are called scions, and plants with roots in the lower part are called rootstocks. Grafting propagation can maintain the characteristics of excellent plant varieties, accelerate the growth and development of plants, harvest medicinal materials in advance, and enhance the ability of plants to adapt to the environment. Among medicinal plants, terminalia chebula, cinchona, papaya, hawthorn, bitter orange and magnolia flower are used for grafting propagation.
There are three methods of grafting: branch grafting, bud grafting and butt joint:
① Branch grafting can be divided into various forms, such as split grafting, tongue grafting and bridging, among which split grafting and cut grafting are the most commonly used. Cutting is mostly carried out before the trees begin to sprout in early spring. The diameter of rootstock should be 2 ~ 3 cm. Cross-cut the rootstock at a position 2 ~ 3 cm or even higher from the ground. Select the part with thick skin and smooth texture to cut vertically down to a depth of about 3cm. Take a scion 2 ~ 3cm long, cut it into two sections, insert it into the split of the rootstock, align the cambium of the scion and the rootstock, fasten it and bury it.
(2) Bud grafting Bud grafting is to cut a piece of bud from the scion, graft it on the rootstock, and germinate from the bud after survival to form a plant. According to the different shapes of bud grafting, it can be divided into several methods, such as bud grafting, pointed grafting, tube bud grafting and bud eye grafting. At present, bud grafting is the most widely used method. In late summer and early autumn (July to September), select rootstocks with a diameter of more than 0.5 cm, and cut a T-shaped mouth, the depth should be cut through the cortex, and the xylem should not be hurt or slightly injured, and the section should be straight. Cut the shield-shaped buds with xylem on the scion with a bud grafting knife, insert the incision, make the buds close to the endodermis of the rootstock, and tie them tightly with hemp skin or film.
(3) Butting method: Cut two branches to be butted together from the opposite side, each with the same shape and size, then stick a piece of bark 2-5 cm long, and then tie it firmly with plastic strips. After survival, the scion is cut from the mother plant. [2]
sexual reproduction
Sexual reproduction is also called seed reproduction. The seedlings propagated by common seeds have strong adaptability to the environment and large propagation coefficient. Seeds are living things in a dormant state. Only good seeds can produce good offspring. There are many kinds of medicinal plants, and their seeds are different in shape, size, color, longevity and germination characteristics.
Seed characteristics
(1) Seed dormancy Seed dormancy is a phenomenon that it is temporarily unable to germinate or difficult to germinate due to internal or external factors. The dormancy period of seeds varies with plant species and varieties. There are many reasons for seed dormancy, both internal and external, including the following aspects: First, the seed coat is too thick and hard, or waxy, which affects seed germination, such as lotus seeds and andrographis paniculata; The second is post-ripening, because the embryo differentiation and development are incomplete (such as ginseng and ginkgo), or although the embryo differentiation and development are complete, it is not mature physiologically and cannot germinate (such as peach and apricot); Thirdly, there are inhibitory substances in the fruit, seed coat or endosperm, such as hydrocyanic acid and organic acid, which hinder the germination of embryos.
(2) The germination period of seeds refers to the number of years that seeds keep their germination ability. The life span of seeds of various medicinal plants varies greatly. The short life span is only a few days or less than 1 year, such as cinnamon seeds, which lose their germination ability once dried, while the life span of angelica sinensis and angelica dahurica seeds is less than 1 year. The germination period of most medicinal plant seeds is 2-3 years, such as burdock, coix lachryma-jobi, milk thistle, platycodon grandiflorum, isatis root and safflower. Proper storage conditions can prolong the life of seeds. But it is best to use fresh seeds in production, because the germination rate of seeds in alternate years is often very low.
seed treatment
Seed treatment before sowing is an economical and effective measure to increase production. It can improve seed quality, control seed diseases and insect pests, break seed dormancy and promote seed germination and seedling growth. There are many methods of seed treatment, which can be summarized into the following categories.
① chemical treatment
A. For general chemical treatment, it is necessary to select appropriate chemicals and concentrations according to the characteristics of seeds and strictly control the treatment time to achieve good results. For example, treating licorice seeds with sulfuric acid can also break the seed coat barrier and improve the germination rate. The seeds of Changium smyrnioides were soaked in 0. 1% baking soda and 0. 1% potassium bromide solution for 30 minutes and then sowed, which could germinate 10 ~ 12 days earlier, and the germination rate increased 10%.
B. The seeds of Achyranthes bidentata, Angelica dahurica, Saposhnikovia divaricata and Platycodon grandiflorum treated with growth regulators can improve the germination rate.
C trace elements commonly used in trace element therapy are boron, manganese, zinc, copper and molybdenum. For example, the seeds of Platycodon grandiflorum were soaked in 0.3% ~ 0.5% potassium permanganate solution for 24 hours, and the yields of seeds and roots were improved.
② Physical factor therapy
A. Soaking seeds alternately with cold, warm or variable temperature can not only soften the seed coat, enhance permeability and promote seed germination, but also kill germs carried inside and outside the seeds and prevent the spread of diseases. For example, soaking andrographis paniculata seeds in warm water at 37℃ for 24 hours can significantly promote germination, and soaking Coix lachryma-jobi seeds in cold and hot water alternately has a good effect on preventing smut.
B. Sun-dried seeds can promote the after-ripening of some seeds, improve the germination rate and germination potential, and prevent pests and diseases.
C. mechanical damage treatment uses mechanical methods to damage the seed coat, break the seed coat barrier and promote seed germination. For example, seeds such as Astragalus membranaceus, Glycyrrhiza uralensis Fisch and Andrographis paniculata can be scraped with coarse sand and then soaked in warm water, so that the germination rate is obviously improved.
D. stratification treatment stratification method is a common method to break the dormancy of seeds, as well as ginkgo, ginseng, coptis and so on. This method is usually used to promote after-ripening. The method is to mix the seeds with wet sand and store them at a lower temperature.
(3) Biological factors are mainly used for seed dressing in production.
sow seeds
(1) Soil preparation includes ploughing, soil preparation and ridging. When ploughing, base fertilizer should be applied, which is especially important for root medicinal plants. After ploughing, the clods should be finely divided to prevent the seeds from sprouting normally, and ridging should be carried out according to the plant characteristics and local climate characteristics. For example, in the south, high ridges are usually used to grow medicinal plants with roots. The width of the boundary should be convenient for operation and management.
② The characteristics of medicinal plants in sowing date are different, and the sowing date is very inconsistent. But it is usually sown in spring and autumn. Generally, millet with poor cold tolerance and short growth period and woody plants without dormancy characteristics are planted in Yichun area, such as Coix lachryma, Perilla frutescens, Schizonepeta tenuifolia and Phellodendron amurense. Plants with strong cold tolerance and long growth period or seeds that need dormancy should be sown in autumn, such as Glehnia littoralis, Angelica dahurica and Magnolia officinalis.
Because of the great climate difference in different parts of China, the sowing date of the same medicinal plant in different areas is also different. For example, safflower should be planted in autumn in the south, but in spring in the north. Every medicinal plant has a suitable sowing date in a certain area. For example, Angelica sinensis and Angelica dahurica are sown too early in autumn, and it is easy to bolting in the next year, so that the roots cannot be used as medicine. However, sowing after the party will affect the yield and even cause freezing injury. In the production process, attention should be paid to determining the appropriate sowing date.
③ Sowing method
A. There are three methods for live broadcast: hole broadcast, drill broadcast and broadcast broadcast broadcast. In the process of sowing, we should pay attention to sowing density and soil covering depth. For example, big seeds should be sown deep, small seeds should be sown shallow, clay should be sown shallow, and sand should be sown deep.
B. Eucommia ulmoides seedlings are transplanted. Cortex Phellodendri, Cortex Magnolia Officinalis, Flos Chrysanthemi, Atractylodis Rhizoma, Radix Codonopsis, Rhizoma Coptidis, Rhizoma Belamcandae, etc. By raising seedlings in seedbeds and then transplanting them into the fields. Seedling transplanting can improve the land utilization rate and facilitate the management and cultivation of strong seedlings.