What is the grafting technique of plants?

Grafting:

The advantage is that varieties with good genetic characters can be obtained. Grafting is to put the branches or buds of a plant, enamel me to restore the ginseng mace? On a stem or root. The former is called scion and the latter is called rootstock or platform wood. The scion usually has 2-4 buds, which becomes the upper part or top of the plant after grafting, and the rootstock becomes the root part of the plant after grafting. The success of grafting first depends on the affinity between the scion and the rootstock, generally speaking, the closer the plant relationship is, the stronger the affinity is, and it also depends on the regeneration ability of cambium cells on the cutting surface of the two plants. as well as the quality of grafting technology and other factors. Grafting is often used for the cultivation of excellent fruit trees, such as apples, pears, oranges and so on.

A brief introduction to the grafting technology of bonsai plants what is grafting?

Grafting is to attach some organs of one plant, such as buds or branches, to the stem or root of another plant, so that the two parts can heal each other and grow into a complete plant. The buds or branches grafted are called scions (commonly known as yards), and the plants that accept scions are called rootstocks (commonly known as mother and son, Taiwan wood, foot wood). Rootstocks mainly absorb water and inorganic salts. The seedlings obtained by grafting are called grafted seedlings.

What is the principle of graft survival?

Grafting is a reproductive method that makes use of the ability of plant regeneration. The most powerful place of regenerative energy of plants is the forming layer. It is located between the xylem and phloem of plants. It can absorb water and minerals from the outer phloem and the inner xylem to divide itself and produce xylem inward and phloem outward, making the branches of the plant thicker and thicker. Grafting is to make the cambium of the cutting surface of the scion and the rootstock close to each other, differentiate the callus because of trauma, and the developed callus combine with each other, fill the gap between the scion and the rootstock, communicate and dredge the tissue, so that nutrients can transmit to each other enough to form a new plant.

What are the internal factors that affect the survival of grafting?

The affinity of rootstock and scion refers to the similarity of internal tissue structure, genetic and physiological characteristics between rootstock and scion, and the ability to grow normally by grafting. Affinity mainly depends on the genetic relationship between rootstock and scion. Generally speaking, the closer the kinship is, the stronger the affinity is. The genetic relationship between the same genus and the same species is close, and the grafting is easy to survive. For example, double peony grafted on double peony, walnut grafted on walnut, rose grafted on rose, and peach grafted on mountain peach are the easiest to survive. This grafting combination is called "common rootstock".

The grafting affinity between different genera of the same family is small, and the grafting is not easy to succeed. There is less affinity between different families, so it is difficult for grafting to succeed.

What are the external factors that affect the survival of grafting?

1. Temperature

The optimum temperature for callus growth is about 20-25 degrees Celsius.

2. Interface humidity

Keeping high humidity is beneficial to the growth of callus. Generally, plastic bags and wax seals are used to maintain the humidity of scions and rootstocks.

3. Lighting

Light has an obvious inhibitory effect on callus, and the callus grows well under dark conditions, so it is necessary to shade the callus after grafting. It is generally covered with soil or opaque materials to create dark conditions.

4. Quality of rootstock

Rootstocks and scions have strong ability to live. Generally choose the Lignified crown, do not choose the growing branch, because the growing branch is easy to lose water.

5. The living habits of rootstocks

The living habits of rootstock and scion should be suitable. Generally, the survival rate of first germination of rootstock is high, while that of scion is low, because the scion is easy to lose water when it germinates first. For example, when the top bud of persimmon is grafted on Junqianzi (round jujube), the survival rate is high, regardless of whether Junqianzi sprouts or not.

6. Grafting period

Grafting is closely related to air temperature, soil temperature and the active state of rootstocks. Therefore, the grafting period should be selected according to the characteristics of flower species.

7. Grafting technique

The interface is required to cut smoothly, fast and skillful.

When is it suitable for grafting?

Branch grafting is mainly carried out before the germination of early spring flowers and trees. At this time, the tissue of rootstock and scion is full, and the temperature and humidity are also beneficial to the formation of layer division and callus growth. It is better for shoot grafting in summer plum rain season.

Budding is mainly carried out in summer and autumn, when the cambium cells are still very active, the tissue of bud grafting is abundant, the grafting is healed in the same year, and it is very suitable to sprout in the following spring after overwintering. Generally, branch grafting is carried out from February to March, lean grafting is from May to June, and bud grafting is carried out from July to September. In cold areas, the time of budding should be advanced to avoid freezing injury.

How to carry out grafting

1. Splice

Cutting is the basic technique of grafting, which is suitable for ground grafting of rootstocks with 1 cm to 2 cm root neck. The specific steps are as follows:

(1) choose anvil and scion. The young shoots with full tissue development were used as scions, and the annual branches with sunny and short internodes were the best, without disease and insect branches, flower bud branches, secondary branches and weak branches. Deciduous trees can be collected and stored after dormancy (sand storage, refrigerator storage or wax seal storage). Roses (rose) are not easy to survive and should be picked up as they are picked. Evergreen trees are generally not stored and can be picked up as they are picked. The rootstock should be strong, well-developed root system, no diseases and insect pests, more nutrient accumulation, and pay attention to the affinity with the scion.

(2) cutting scion. Cut off a section in the middle of the branch, about 10 to 12 centimeters long as a scion. Keep 3-4 buds on the scion, the upper mouth slightly higher than the top bud, to protect the bud from bruising, the lower mouth should be 3-4 cm below the lowest bud. The ear is 5-8 cm long with 3-4 buds. Cut the scion into two sides, one long and the other short. The long face cuts off more than 3 of the xylem, showing a 30-degree slope, the length of the cutting surface is 2.3 to 2.5 cm, and the last bud remains on both sides of the cutting surface; cut a horseshoe-shaped small slope on the opposite side of the long face, cutting it to 45 degrees and 0. 5% long. About five centimeters. These two cut faces should be flat and smooth.

(3) cutting rootstocks. Cut off the branches of the rootstock and cut the rootstock 3 to 4 centimeters above the ground. Cut the end of the anvil flat, then make a light cut on one side of the cut of the rootstock, then cut down vertically, with a length of about 2 to 3 centimeters, and strive to be smooth. Such a section has a large area and is easy to align and closely connect with the scion cambium.

(4) combination. Cut the scion and cut the rootstock. The scion is long facing inward and short facing outward. When inserting people, the scion just touched the lower end of the cut of the rootstock, do not use force to press down, the upper end should expose a line (commonly known as "blank", about 0.3 cm), so that there is room for callus growth.

(5) binding. The combination of rootstock and scion should pay attention to binding. When binding, do not move the scion to form a layer alignment position, loose and tight moderately. You can tie it up from the top down or from the bottom up. Commonly used 0.5 cm wide plastic belt as binding material, good moisturizing performance, difficult to survive flowers and trees should also be coated with wax.

(6) Management. General flowers and trees can be grafted and planted in the open field, as long as the cut part is covered with fine soil, the soil should be 1 cm higher than the scion, exposing only the terminal bud. Camellia can be bagged and planted. However, hotbed cultivation can promote healing and improve the survival rate. In the future, keep watering from the base to keep the mound moist until after budding. After the cutting seedlings survive and spread their leaves, do not rush to release the binding material, but keep it for one or two months. After 1-2 months of grafting, the shoots can sprout. After the bud is unearthed, the sealing soil is gradually removed and the interface is exposed.

2. Splice

When the rootstock is thick and the scion is small, split grafting is used.

(1) rootstock treatment. Cut off the branches of the rootstock, cut the rootstock at the grafting site, and flatten the end of the rootstock. It is required that there should be no nodal scar within 6 cm below the cut. Cut vertically and longitudinally from the center of the cross section of the rootstock. The knife should be sharp and slightly thick. When it is about to split the rootstock,

It's wedge-shaped. The split is 3cm to 4cm deep.

(2) scion cutting method. The scion is also cut into a wedge, the two cutting faces are symmetrical, and the cutting surface is 3-5 cm long.

(3) combination. Pry open the split of the rootstock with a split knife, insert the scion, gently remove the split knife, so that the two sides form a layer of close connection. When the rootstock is thick, it can only aim at one side of the cambium, or one ear can be grafted on the left and right side of the split of the rootstock, and the well-developed branch can be selected after survival. When inserting a scion, the cutting surface of the scion is exposed to 0.5 cm.

(4) binding. After that, it is bound with wool or hemp rope and choked with dirt. Camellia, pine and other twigs can be bagged and moisturized (twigs are often used for splicing).

(5) other operating essentials are basically the same as splicing.

3. Lean against the receiver

The grafting method is mostly used for other kinds of flowers and trees that are difficult to survive by grafting, but precious and difficult to live, such as sweet-scented osmanthus, maple, camellia, bergamot and other citrus. This is because when relying on grafting, the rootstock and scion are pulled together without leaving the mother plant, and the scion is cut off from the mother plant only after survival, so propagation by grafting is the most sure.

The pick-up time is mostly carried out in the period of exuberant flower growth in summer.

For flowers and trees propagated by grafting, the mother plant should be planted next to the rootstock or in the same flowerpot, or the rootstock can be hung from the scion mother tree or placed next to it. The rootstock should choose more than 2-year-old branches with a diameter of 1-1.5 cm, and the scion should choose 1-2-year-old branches with branches on adult plants, with a diameter of 0.6 cm and a length of 15 cm.

Both sides of the rootstock and scion go forward to align the cambium of the rootstock and scion without exposing gaps, so that the cambium of the injured surface is close to each other, and then fasten it with plastic tape or hemp rope to prevent Rain Water from pouring in. After receiving work, cut off the scion at the lower part of the interface, cut off the upper rootstock in batches, and become an independent plant. It is generally required that the crown of the scion mother tree is larger, and the crown of the rootstock is smaller, which can be connected with four or five branches at a time.

No fertilizer is applied after grafting, but the basin soil should always be kept moist. The incision can be healed in 1 to 2 months, and then cut off between the scion and the mother plant to become an independent plant.

4. Ventral graft

Ventral grafting, also known as root grafting, is a branch grafting method without cutting the anvil crown. It is generally grafted at the root edge of the rootstock, which is suitable for the grafting and propagation of Pinus elliottii and Pinus elliottii. It is also used in Sabina vulgaris, Sabina vulgaris and Sabina vulgaris, and has been used in social rhododendron and camellia in recent years.

There are many specific methods of abdominal grafting, among which abdominal grafting, skin insertion and subcutaneous ventral grafting are the most widely used in flower and tree production.

(1) abdominal incision. This is the traditional abdominal connection method, which is the most commonly used and is generally carried out in early spring. The specific steps are as follows (take five-needle pine as an example):

① cutting scion: choose 1-2-year-old five-needle pine branch without disease and insect pests as scion, 5-8 cm long, remove the lower 2-3 cm needle, obliquely cut a knife, about 2 cm long, and cut a small slope on the reverse side, 0. 5% long. About 5 cm, the cutting method is the same as the cutting joint.

② cutting rootstock: choose 2-3-year-old black pine as rootstock (Pinus massoniana can also, but the survival rate is lower than black pine), after digging up with mud, cut off part of the branches and leaves, repair the root system, in the smooth part of the rhizosphere stem, oblique cut a knife, 2.5cm long, deep to the xylem, showing a shield-shaped mouth, can also be slightly cut vertically with xylem, the cut should be slightly longer than the cutting surface of the scion, otherwise it is not easy to close.

③ binding and binding: after cutting the rootstock, the scion should be quickly cut into the rootstock, aim at the cambium, and then bind with plastic film tape. Put a small plastic bag on the scion and joint to prevent dehydration, and remove the plastic bag after the ear bud sprouts.

④ management: the five-needle pine connected by the abdomen should be planted in a high and dry place, and the interface should be covered with soil and moisturizing in the north. In the early stage of healing (about [month), it is best to shade the light, see sparse light later, shade in the hot summer, and avoid exposure when you just put the needle.

(2) subcutaneous abdominal connection. It is an improved abdominal grafting method, which is suitable for grafting in the growing period (June to September). The scion takes the semi-lignified branches of the year, so it is also called ventral grafting of twigs. The survival rate of this method is high. Ear cutting and operation are the same as abdominal grafting. Cut the rootstock into T-shape: first cut a knife horizontally, then cut it longitudinally in the middle of the horizontal line, open the cortex, expose the layer, and finally bind it.

5. Water branch grafting

Water branch connection is also called water plug connection and hanging bottle connection. Used in camellia and rhododendron. In the process of callus survival, the scion replenishes water from the bottle and is not easy to wither.

(1) carve the anvil. The water-grafted rootstock is a perennial old stem or curved thick root, which is first planted in a pot, cut into a tree stump, and sprouted into sparse lateral branches. the upper end of the rootstock is carved into grooves with a round blade, and the upper end is slightly to the xylem. 5 cm left and right.

(2) ear cutting. The scion is about 25 cm long with 3 or 4 leaves at the upper end. The middle is cut into a convex V-shaped, about 3 cm long. The cutting should be as deep as the xylem. Otherwise, it will not grow well.

(3) binding. The cutting surface of the scion should reveal 0.5 cm of the cross section of the rootstock, which is beneficial to the formation of callus. The scion at the junction should be slightly higher than the rootstock (about 3-4 mm) and should not be sunken into the groove. Use binding material to cover all the rootstocks.

(4) hanging bottle. Finally, hang a vial, fill it with water, and fix it at the base of the scion. When the callus survived, remove the hanging bottle, cut off the scion below the interface, and keep it under the shade shed. The binding material can be removed after 1 month. The seedlings grafted with water branches grow rapidly.

Why trim the tillering buds in time?

"tillering bud" mostly refers to the branches that grow from the rootstock base of the grafted seedling, such as rose grafted on the rose rootstock, and those that grow from the rose rootstock are called tillering buds. Such as clove grafting in privet, red maple grafting in green maple and so on, this situation will occur. If the tillering buds on the rootstock are not repaired in time, it is bound to seize the nutrition of the scion, affect its growth and development, and seriously cause the scion to wither and die.

Study on grafting Propagation of Flowers and plants

The following is the learning resources of grafting propagation technology of flowers and plants collected by me from the Internet. I would like to thank the author here (I did not see who the author was when I reprinted it, so I can only thank you silently). The grafting propagation technology of plants illustrated here will bring help to everyone, and there will be fewer detours in the grafting and reproduction of plants in the future.

What is meant by grafting 01, grafting: that is, the branch or bud of one plant is grafted onto the stem or root of another plant, so that the two parts that are connected together grow into a complete plant. In short, grafting is a part of a plant's vegetative organs that is transferred to other plants. Grafting is one of the methods of artificial vegetative propagation of plants: people purposefully connect the branches or buds of one plant to the branches, stems or roots of another plant, so that they can heal and grow together to form a new plant. 02, related name: grafted seedlings (seedlings cultivated by grafting) are called grafted seedlings. The branch or bud used for grafting (that is, the branch grafted) is called scion; the bud used is called grafting bud. The plant that bears the scion (that is, the plant that is grafted) is called rootstock or pedestal (commonly known as foot tree).

03. The advantages of grafted seedlings: ① grafted seedlings can maintain the characters of scions of good varieties, and grow fast, have strong tree potential and bear fruit early, so it is beneficial to accelerate the popularization and application of new varieties. ② can use some characteristics of rootstocks, such as drought and cold resistance, waterlogging and saline tolerance, disease and insect resistance, to enhance the adaptability and stress resistance of cultivated varieties, so as to expand the cultivation range or reduce the production cost. ③ in fruit and flower production, rootstocks can be used to adjust tree potential, dwarf or Arbor to meet the different needs of cultivation or consumption. Most of the rootstocks of ④ can be propagated by seeds, so the propagation coefficient is large, so it is easy to be popularized in large areas in production.

04. Grafting methods: divided into two categories: branch grafting and bud grafting. The former is suitable for spring and autumn, especially in spring, and the latter is suitable for summer. When grafting, the scion should be closely combined with the cambium of the rootstock to ensure its survival.

In scion, the seedling with 4 buds of 2Mel is generally selected, which becomes the upper part or top of the plant after grafting, and the rootstock becomes the root part of the plant after grafting.

Grafting principle: grafting reproduction is a method of breeding excellent varieties of clones, that is, a kind of vegetative reproduction in asexual reproduction, which is often used in plum blossom, rose and so on. Grafting is carried out by using the function of callus after plant injury. Grafting can indicate that the nucleus is the center of genetic control. During grafting, the cambium of the two injured surfaces are closely close and tied together, resulting in cell proliferation and healing into a whole connected by vascular tissue. This is the principle of grafting. The key to grafting is to keep the scion cambium close to the rootstock cambium. The principle of graft survival is that there is a healing phenomenon in the cambium of the junction between two plants with affinity, so that the ducts and sieve tubes communicate with each other to form a new individual. The expression of grafting: grafting is indicated by the symbol "ten", that is, the rootstock is ten scions; it can also be expressed as "/", but its meaning is just the opposite of that expressed by "ten". Usually the scion is placed before the "/". Namely: scion / rootstock = = rootstock + scion, sweet-scented osmanthus / privet = = privet + sweet-scented osmanthus, walnut / wild walnut = = wild walnut + domestic walnut.

Influencing factors: the main factor affecting the survival of grafting is the affinity of scion and rootstock, followed by the technology of grafting and the management after grafting. The so-called affinity is the ability that scions and rootstocks are the same or similar to each other in internal organizational structure, physiology and heredity, so that they can be combined with each other. If the affinity is high, the survival rate of grafting is high; otherwise, the survival rate is low. Generally speaking, the closer the plant relationship is, the stronger the affinity is. For example, apples are connected to sand fruits, pears to du pears and Qiuzi pears, persimmons to black dates, walnuts to Juglans mandshurica and so on.

Grafting significance: in the process of production practice, there are many examples of the improvement of economic value by grafting, such as ordinary metasequoia, which is worth one yuan; and after being cultivated into Metasequoia glyptostroboides by means of grafting, the economic value is increased by more than 20 times; the ordinary large-leaf privet tree is worth several cents; and by means of grafting, after it is cultivated into a colored leaf frame tree, its economic value is nearly a hundred times. It can be seen that grafting is of great significance to the improvement of varieties and the improvement of economic value.

Grafting is of great significance to the reproduction of some fruit trees that do not produce seeds (such as persimmon and citrus varieties). Grafting can not only maintain the excellent characters of scion varieties, but also make use of the favorable characteristics of rootstocks to achieve early fruiting, enhance cold resistance, drought resistance, disease and insect pest resistance, and economically utilize breeding materials and increase the number of seedlings. It is often used in the reproduction of fruit trees, trees and flowers; it is also used in raising seedlings of melons and vegetables.

It can improve 01 and enhance the disease resistance of plants. Cucumber grafted with black seed pumpkin can effectively control cucumber Fusarium wilt and postpone the occurrence of downy mildew, while eggplant grafted with CRP and tomato can basically control the occurrence of Verticillium wilt. 02. Improve the low temperature tolerance of the plant. Because of the well-developed root system and strong stress resistance of rootstocks, the grafted seedlings are obviously tolerant to low temperature. For example, the cucumber grafted with black seed pumpkin has good root elongation at low temperature, and the root system can still grow normally when the ground temperature is 12-15 ℃ and the air temperature is 6-10 ℃. 03. It is helpful to overcome the harm of continuous cropping. Cucumber root system is fragile, avoid continuous cropping, solar greenhouse cultivation is very easy to be damaged by soil salt and harmful substances, after switching to black seed pumpkin root, the harm of soil salt and harmful substances can be greatly reduced. 04. The absorption range and capacity of roots were expanded. The root system of the grafted plant is twice as large as that of the self-rooted seedling, and it can absorb about 30% more nitrogen, potassium and more than 80% phosphorus than the self-rooted seedling in the same area, and can utilize the phosphorus in the deep layer of the soil. 05. It is beneficial to increase the output. The grafted seedlings have large thick stems and leaves, which can increase the yield by more than 40%. Tomato uses late-maturing varieties as rootstocks and early-maturing varieties as scions, which can not only retain the early maturity, but also greatly shorten the fruiting period and increase the total yield.

Grafting site

Grafting is best carried out in a greenhouse-shading nets or grass curtains should be used to shade in high temperature season to avoid excessive wilting of seedlings. For example, the grafting of eggplant in late winter in July is in the period of high temperature, heat prevention and cooling is the key. In the low temperature season (such as the grafting of cucumber and muskmelon overwintering stubble from the end of September to the beginning of October), the heat preservation should be the main, and the low temperature is not conducive to wound healing; when grafting, the suitable temperature should be 24 ℃, and the air relative humidity should be more than 75%. When there is not enough humidity, use a sprayer to spray water into the air or walls to increase humidity. Grafting appliance 01, blade: that is, a general shaving double-sided blade, which is broken in half when grafted, which not only saves the blade, but also is easy to operate. 02. Bamboo stick: one is used to insert a hole on the rootstock, and its thickness is the same as that of the young stem of the scion seedling: one end is cut into a wedge; the other end is not strict in thickness. Cut one end into a single wedge and use it to pick out the growing point of the pumpkin. Grafting clamps: used to fix scions and rootstocks, grafting clips sold on the market are: one is eggplant grafting clip, the other is melon grafting clip. The old grafting clip should be disinfected with 200 times formaldehyde solution for 8 hours in advance. Operators' fingers, blades and bamboo sticks are sterilized with 75% alcohol (medical alcohol) and sterilized every 2 hours to prevent miscellaneous bacteria from infecting the wound. But the blades and bamboo sticks wiped with alcohol cotton balls must wait until they are dry before they can be used, otherwise the survival rate will be seriously affected. 04. Grafting machine: as the obstacle of continuous cropping of melons is becoming more and more prominent, vegetable grafting technology has been paid more and more attention; professional households and seedling companies have also emerged as the times require. For professional seedling households and seedling companies, if they rely on artificial grafting, it is easy to delay the grafting opportunity because of low work efficiency and low level of grafting technology. Hope to use grafting machine operation, small and semi-automatic grafting machine, because of the low price, popular in the market. Taiwan Sono grafting machine is a semi-automatic grafting machine, the highest productivity is about 310 plants per hour, and the success rate of grafting is 90%. Because of its simple structure, easy operation and low cost, it not only has a certain sales volume in foreign countries and our country, but also is suitable for semi-mechanized operation of fruit tree branches, watermelons, cucumbers and other melon vegetable seedlings.

Grafting process when the scion is grafted on the rootstock, the wound is covered with a brown film on the surface of the rootstock and scion wound due to the residue of dead cells. Then, under the stimulation of callus hormone, the cells around the wound and cambium cells divide vigorously, and the brown membrane is broken to form callus. After the callus increased and the gap between the scion and the rootstock was filled, the parenchyma cells of the healing tissue of the rootstock and the scion were connected to each other, connecting the cambium of the two. The healing tissue differentiates continuously, forming a new xylem inward and a new phloem outward, which makes the vessel and sieve tube communicate with each other, so that the rootstock is United into a unity and a new plant is formed. Affinity between rootstock and scion: grafting, affinity refers to the ability of rootstock and scion to heal and grow normally after grafting. Specifically, it refers to the internal tissue structure, genetic and physiological characteristics of rootstock and scion, which can survive by grafting and adapt to each other physiologically after survival. Whether the grafting can be successful or not, affinity is the most basic condition. The stronger the affinity, the better the grafting healing, the higher the survival rate, and the more normal the growth and development. There are many manifestations of incompatibility or low affinity in rootstock and panicle, such as poor healing of ①: it can not heal and survive after grafting, or poor healing ability and low survival rate. Some can heal, but the buds do not germinate, or the firmness of healing is very poor, and it is easy to break after germination. The growth result of ② was abnormal: although it could grow after grafting, the branches and leaves were yellowed, the leaves were small and clustered, and the growth was weak, resulting in death. Some early formation of a large number of flower buds, or abnormal fruit development, poor meat, fruit deformity. The growth of ③ rootstock interface is not coordinated, resulting in the phenomenon of "big foot", "small foot" or "ring hanging" (as shown in the following figure).

Incompatibility in the later stage of ④: some grafted combinations healed well and could grow and bear fruit normally, but showed serious incompatibility after several years. If peach is grafted on the rootstock of hairy cherry, shortly after entering the fruiting period, the leaves are yellowed, scorched shoots, branches and even the whole plant are senescent and dead. The affinity depends on the genetic relationship between rootstock and panicle. Generally speaking, the closer the kinship is, the stronger the affinity is. The affinity between the same species or varieties is the strongest, such as Chinese chestnut with Chinese chestnut, Qiuzi pear with Nanguo pear, etc., and the affinity among different species of the same genus is stronger than that of different families and different genera. In addition, the tissue structure, metabolic status and physiological and biochemical characteristics of rootstock are closely related to the grafting affinity. For example, Chinese chestnut grafted on Japanese chestnut, because the latter absorbed more inorganic salts, resulting in incompatibility, while Chinese chestnut grafted on Chinese chestnut had good affinity. When grafting persimmons and walnuts, they often affect survival because of more tannins.

The period of grafting: the success or failure of grafting is closely related to air temperature, soil temperature, rootstock and the active state of scion. According to the characteristics of tree species and the requirements of methods, the appropriate time for grafting should be selected. Grafting is not good in rainy season and windy weather. Generally speaking, it is appropriate to use 20 ℃ and 25 min.

Temperature: there are differences in temperature requirements among different tree species and grafting methods. For example, the optimum temperature for callus formation after walnut grafting is 26 ℃ 29 ℃, the optimum temperature for grape indoor grafting is 24 ℃ 27 ℃, the callus formed more than 29 ℃ is tender and easy to be damaged during planting, and the healing tissue is formed slowly when it is below 21 ℃. Humidity: the interface maintains a high humidity, which is conducive to callus formation, but do not immerse it in water. Oxygen: the formation of callus requires sufficient oxygen, especially for some tree species with more oxygen, such as grape hard branch grafting, the interface should be sparsely bound without wax. Light: light can inhibit the growth of callus.

Grafting method

According to the difference of scion (that is, the material taken), grafting can be divided into three categories: bud grafting, branch grafting and root grafting.

01. Bud grafting: a grafting method in which a bud slice (with or without xylem) is cut from a branch as a scion, inserted into a cut on the rootstock and tied to make it close to heal. The bud grafting should be carried out in the slow growth period, so the cambium cells are still very active and the tissue of bud grafting has been enriched. It is very suitable for grafting to heal this year and to sprout into seedlings next spring. If the grafting is too early, the buds germinate in the same year, but it cannot be lignified in winter and is easy to be frozen; if the grafting is too late, the bark of the rootstock is not easy to peel off. Climate also has an effect on grafting, and cambium and callus can only move at a certain temperature. When the air humidity is close to saturation, it is most suitable for healing, grafting outdoors, we should pay more attention to weather conditions. Because of the different forms, bud grafting can be divided into different methods, such as bud slice grafting, sentry grafting, tube bud grafting and bud eye grafting, among which bud grafting is the most widely used. The utility model has the advantages of simple operation method, fast grafting speed, economical utilization of rootstock and scion, one-year-old rootstock seedlings can be grafted, and it is easy to heal, firm joint, high survival rate and fast seedling formation, which is suitable for mass propagation of seedlings. The suitable period of bud grafting is long, and the grafting does not cut the rootstock at that time, the first grafting is not alive, and supplementary grafting can be carried out. The main budding methods are introduced below.

A. "T" bud grafting: because the cut of the rootstock is very similar to the "T" word, also known as "T" bud grafting. Also because the cut bud piece is shield-shaped, it is also known as shield-shaped bud grafting. T-shaped bud grafting is a widely used grafting method in the raising of fruit trees, and it is also a method with simple operation, high speed and the highest survival rate of grafting. The length of the bud is 1.5-2.5cm and the width is about 0.6cm, and the diameter of the rootstock is between 0.6-2.5cm, but the survival is affected by the thickening of the rootstock and the thickening of the bark. Specific operation: sprout: the left hand holds the scion, the right hand holds the grafting knife. Select the full buds on the scion, first cut a knife across the 0.5cm above the buds, cut through the skin layer, and the transverse cut is about 0.8cm. Then cut an upward oblique knife at 1-1.2cm below the bud, from shallow to deep, deep into the essential part, and intersect with the transverse incision on the bud. Then use the right hand to pick up the shield bud piece. Open the rootstock: choose a rootstock from the ground 5-6cm, smooth non-branching place cross-cut 1 knife, the depth to cut off the cortex to the xylem is appropriate. Then cut 1 knife length 1-1.5cm vertically in the middle of the transverse incision. Joint: pick out the cortex of the rootstock with the tip of the budding knife, insert the bud into the "T"-shaped incision, and align the transverse incision of the bud with the transverse incision of the rootstock. To bind with plastic strips. First tie a tight one above the bud, then tie a tight one under the bud, and then tie the buckle three or four times in a row. Pay attention to expose the petiole, dew bud can not show bud. b. Embedded bud grafting: when the tree species with angular or furrowed branches, such as Chinese chestnut, jujube, or other plant materials, rootstocks and scions are not detached from the skin, embedded bud grafting can be used. Cut 1 knife downwards at 0.8-1 cnt above the ear bud, penetrate into the xylem, about 1.5cm, and then connect with the incision of the first knife at an oblique angle of 30 °at 0.5-0.6cm below the bud, and remove the inverted shield bud. The incision of the rootstock is slightly longer than that of the bud piece. After inserting the bud piece, it should be noted that the upper end of the bud piece must expose the cortex of the L-line rootstock. Finally, fasten it with a plastic strip. c. The method of relying on grafting: hang the rootstock on the mother plant of ear picking, select the branches with similar thickness and smooth branches on both sides, cut off the thick branches and cut off the thick branches, and the cutting surface is 5cm long, align the cambium of both sides, and fasten it tightly with plastic film strips. After the interface between the two is healed, cut off the branches of the mother plant of the scion at the interface, and cut off the upper part of the rootstock to form a new plant.

d. Insertion method: first, the true leaves and growth points of bottle gourd seedlings were removed with bamboo sticks, and at the same time, the bamboo sticks were inserted downward from the growth point between the cotyledons of rootstocks to a depth of 0.5-0.7cm, then the watermelon seedlings were cut into a wedge of about 0.5cm with a blade under the cotyledons, and the watermelon seedlings were inserted while pulling out the bamboo sticks, which is the direct insertion method. Another method of oblique insertion is the oblique insertion method, in which an one-sided wedge-shaped bamboo stick as thick as the scion is used to insert the plane of the bamboo stick downward from the base of one side of the cotyledon of the bottle gourd seedling to the other side, and the tip of the bamboo stick is topped to the young stem epidermis or pierced through the epidermis, and then cut into an oblique stubble 1 cm below the cotyledon of the watermelon seedling, and the oblique stubble of the young stem of the watermelon seedling is quickly inserted downward while pulling out the bamboo stick. After picking it up, move it into the shed to strengthen the management.

02. Grafting method: the branch with several buds or 1 bud is attached to the rootstock, which is called branch grafting. The advantages of branch grafting are high survival rate and fast growth of grafted seedlings. Under the condition that the rootstock is thicker and the rootstock is not separated from the skin, branch grafting is often used, such as repairing the rootstocks that did not survive budding in autumn in spring. Root grafting and indoor grafting are also mostly used in branch grafting. Disadvantages: the operation technology is not as easy to master as bud grafting, and use more scions, the rootstock requires a certain degree of coarseness. The common grafting methods are cutting, splitting, skin grafting, abdominal grafting, tongue grafting and so on. a. Splicing method. This method is suitable for site grafting of rootstocks with thick root neck 1-2cm, and it is a commonly used method in branch grafting. Cutting scion: the scion is usually 5-8cm long, with three or four buds is suitable. Cut the lower part of the scion into two cutting faces, one long and one short, the long side is on the same side of the lateral bud, cut off the essential part of lmax 3 or more, the length is about 3cm, and cut a horseshoe-shaped slope on the opposite side of the long surface, the length is about 1cm. Rootstock treatment: cut the rootstock at 3-4cm off the ground. Select the place where the rootstock skin is thick, smooth and smooth, cut the cutting surface of the rootstock flat, and then cut straight down at the edge of the essential part. The width of the notch is equal to the diameter of the scion and the depth is generally 2-3cm. Joint: cut the scion inward and insert it into the cut of the rootstock. Align the scion with the forming layer of the rootstock. If you can't align both sides, you can align one side. Binding: wrap it tightly with plastic and wrap all the cracks and cuts tightly. Be careful not to touch the scion when binding. b. Splicing method. The rootstock removed the growing point and heart leaves, cut the 8-10 mm-long crack vertically between the two cotyledons; cut it into a 8-10 mm long double-sided wedge on both sides of the young stem about cm below the scion cotyledon, and gently inserted the scion double wedge facing the interface of the quasi-rootstock, so that the two incisions fit tightly and the grafting clamp was fixed. It is an ancient grafting method, which is widely used. It can also be used for thinner rootstocks and is very suitable for high grafting of fruit trees. Cutting scion: the scion is cut into a wedge, with 2 symmetrical cutting surfaces and a length of 3-5cm. The outside of the scion should be slightly thicker than the inside. If the rootstock is too thick and the clamping force is too large, the inner and outer thickness can be the same or the inside is slightly thicker to prevent the joint from being clamped. The cutting surface of the scion is required to be straight and smooth, and the rough cutting surface is not easy to combine closely. When cutting the scion, use the left hand to hold the scion and the right hand push knife to cut into the scion obliquely. Push knife force should be uniform, consistent, push knife direction should be consistent with the direction of the knife. If the force is uneven, the force before and after the force is inconsistent, the cutting surface will not be smooth, and the upward deviation of the midway direction will make the cutting surface not straight. If the knife is uneven, one or two more knives can be mended to make the cutting surface meet the requirements. Rootstock treatment: cutting or sawing the rootstock at the grafting site. The position of the cut is very important, so that the surface of the stump is smooth and the texture is straight, at least there is no scar in the upper and lower 6cm, otherwise the seam is not straight and the wood is split to one side. After the grafting site is selected and cut, a splitter is used to split one knife in the center of the rootstock to make the split 3-4cm deep. Joining and binding: pry open the split of the rootstock with the wedge of the cleaver, gently insert the scion into the anvil to make the scion thick on the outside and thin on the inside, and then gently remove the chopper. Special attention should be paid to aligning the cambium of the rootstock and the forming layer of the scion when inserting. Generally speaking, the cortex of the rootstock is thicker than that of the scion, so the outer surface of the scion is slightly more inward than the outer surface of the rootstock, so that the cambium can align with each other. The xylem can also be used as the standard to align the rootstock with the xylem surface of the scion so that the cambium is aligned. When inserting scions, all the cutting faces should be inserted, and the cutting faces around 0.5cm should be exposed. In this way, the cambium interface between scion and rootstock is larger, and it is beneficial to the formation and healing of meristem. Thicker rootstocks can insert two scions, one on each side. Then, tie it tightly with a plastic strip. c. Tongue connection. Commonly used for grape branch grafting, generally suitable for rootstock diameter lcm about thick, and rootstock roughly the same thickness of grafting. On the back of the scion, the bud was cut into a slope of about 3cm length, and then split up along the branch at 1 point from the bottom to the top of the cutting surface, and the split was about 1cm, showing a tongue. The rootstock is also cut into a slope about the length of 3cm, which is split down along the rootstock at 3 points from top to bottom, and the split is about 1cm, corresponding to the slope of the scion. Insert the split of the scion into the split of the rootstock so that the tongue of the rootstock and the scion cross, then aim at the cambium and insert it inward. If the thickness of the rootstock is not consistent, the cambium can be aligned with one side. After joining, you can tie it up. d. Machine realization method: the use of grafting machine operation, small and semi-automatic grafting machine, because of the low price, popular in the market. Application effect picture of grafting machine:

03. Root grafting: (to be determined) the development of grafting has a long history in China. There are records about grafting more than 2000 years ago, which is called "transferring flowers to trees". People have long found the natural grafting phenomenon that trees in the forest are close to each other after rubbing and damaging each other, which is called "wooden link" in ancient China. Grafting is a kind of production technology inspired by this natural phenomenon. In ancient Europe, both Aristotle and Pliny, an ancient Roman scholar, mentioned grafting one after another. In the 5th century, the application of branch grafting and bud grafting technology in the Mediterranean region is increasing. In the 16th century, there were branch grafting methods in England, such as split grafting, crown grafting and tongue grafting. Budding technology was widely used in Europe after the 17th century, when it was mainly used to propagate stone fruit trees such as peach, nectarine and apricot. The early records of grafting in China are found in the Book of Gu Sheng, which contains the method of grafting 10 bottle gourd seedlings into a vine. Qi Min Yao Shu in the Northern Wei Dynasty has a detailed description of the selection of rootstocks and scions, the period of grafting, how to ensure the survival of grafting and the influence of grafting. In the hundreds of years of the 13th century, grafting technology has made great progress in ornamental plants and fruit trees such as peony and chrysanthemum. In the Southern Song Dynasty, Han Yanzhi praised the magic of citrus grafting technology in his book "Orange Records" and said that "human resources are involved in every such thing". In the 13th century, due to the development of sericulture, mulberry grafting was paid attention to. In his Qunfang Spectrum in the 17th century, Wang Xiangjin talked about the combination of grafting and culture to promote plant variation. In the early Qing Dynasty, works such as Flower Mirror further affirmed the effect of grafting in changing plant characters. With the application of modern scientific methods, the history of grafting is less than 100 years, but it has developed rapidly. The practical application of grafting in the production of fruit trees is not only to maintain the excellent characteristics of varieties, but also to bear fruit early, overcome the difficulties of some species that are not easy to reproduce, resist disease and immunity, and prevent insect pests; in addition, the wind-soil adaptability of rootstocks can also be used to expand the cultivation area, improve yield and quality, and dwarf or Arbor fruit trees (figure 3). In the production of ornamental plants, we often use the root grafting method (figure 3a) to restore the tree potential and preserve the old and famous trees; the bridging method (figure 3b) to save the big trees whose trunks have been killed (see tree body protection); and the high connection method to replace the original inferior species of big trees to make up for the incomplete crown, and so on. The use of high grafting can also solve the problem of self-pollination of non-fruiting or dioecious fruit trees, as well as the reproductive shape of special ornamental tree varieties such as Robinia pseudoacacia, weeping peach, weeping plum and so on. In forest tree breeding, grafting techniques are adopted to dwarf mother plants in order to facilitate cross operation and establish seed orchards and ear orchards. It is a common method for breeders to use special rootstocks to promote plant flowering, such as sweet potato grafted on water spinach or moonlight flowers to achieve the purpose of hybridization. In addition, grafting is often used as a means to study plant physiology, plant pathology, plant virology and plant histogenesis. In order to clarify the local synthesis process and stage development of some substances in individual organs, many scholars often use grafting. The application of grafting machine and the effect of grafting machine-- as shown in the following figure

Development trend the scope of application of grafting technology is still expanding. In addition to fruit trees and ornamental trees, more and more herbaceous plants such as vegetables, trees and other economic plants, such as rubber trees and cocoa trees, are being grafted. In terms of grafting materials, from ordinary branch grafting and bud grafting to tender branch grafting, leaf grafting, germ grafting, growing point grafting, bud eye grafting of bulbs and tubers, and even the grafting of inflorescence, stigma, ovary and fruit, almost all parts of the plant can be used for grafting. Since 1980, micropropagation and micrografting have been developed on the basis of tissue culture technology. In sterilized tissue culture, virus-free seedlings of citrus, apple and other fruit trees can be cultured with 0.10-0.14mm in vitro shoot tip micrografting, which has been applied in China, the United States and Spain. In addition to the continuous improvement of grafting technology, further exploring the nature of grafting affinity and the mechanism of rootstock influence will be the focus of future research. Note 01. Select rootstocks and scions with strong affinity: affinity refers to the ability of rootstocks and scions to heal after grafting. In general, the closer the relationship is, the stronger the affinity is, the higher the survival rate of grafting is. 02. Select rootstocks and scions with strong vitality: vitality is related to the nutrients accumulated by the vegetative organs of rootstocks and scions. The more nutrients accumulated by vegetative organs, the stronger the vitality will be. Therefore, before grafting, the water and fertilizer management of rootstocks should be strengthened to allow them to accumulate more nutrients, and branches with mature and full bud eyes should be selected as scions. 03. Choose the best time for grafting: generally, branch grafting should be carried out in the early spring before fruit tree germination, because at this time, the tissue of rootstock and scion is enriched, temperature and humidity are also conducive to the vigorous division of cambium and speed up wound healing. On the other hand, bud grafting should be carried out in the slow growth period, so that the grafting can survive, and it is better to sprout and grow into seedlings in the next spring. 04, the use of plant hormones to promote healing: the scion was treated with plant hormones before grafting, such as soaking in 200-300PPM naphthalene acetic acid for 6-8 hours, it can promote the activity of cambium, thus promote wound healing and improve the survival rate of grafting. 05. Standardize the technical operation, the grafting should be done quickly, and the rootstock and scion should be cut strictly according to the technology, and the grafting surface should be smooth, so that the cambium of rootstock and scion should be closely connected, strapped and loosened appropriately, and unbound in time.