What are the grafting methods and what is the physiological basis of grafting survival?

First, the main external factors affecting the survival of grafting:

1, temperature: grafting in spring is too early, the temperature is low, the cambium of rootstock and scion is just beginning, the callus proliferation is slow, and it is not easy to survive after grafting. Generally, the callus formation ability of flowers and trees branches is very weak at 0℃; At about 4℃, callus formation is very slow; Callus proliferated rapidly in the range of 5℃ ~ 32℃, and accelerated with the increase of temperature. 32℃ ~ 39℃ will slow down the speed and cause cell damage; When the temperature exceeded 40℃, the callus died. Therefore, the grafting time without branches and leaves in spring is generally from late March to early May. Bud grafting is often used in the production of flowers and trees. Although it can be carried out in spring, summer and autumn, it is also necessary to avoid high or low temperature periods.

2. Humidity: Humidity includes grafting humidity, atmospheric humidity and soil humidity. Flowers and trees with suitable humidity are easy to survive after grafting. According to the experiment, the water content of scion and rootstock is about 50%. If the water content of rootstocks and scions is low, they should be watered in advance to maintain proper humidity. When grafting, the air humidity is suitable, and a water film can be kept on the surface of the cutting layer, which can promote callus. If the air humidity is too dry when grafting, it is necessary to artificially create conditions, such as spraying water in advance or covering the scion with wet cloth, or dressing the wound with plastic film and covering the grafting surface with wet soil.

3. Light and moisture: under dark conditions, the callus produced on the scion section is milky white and tender, and the joint surface between rootstock and scion is easy to heal; The callus formed under strong light is few and hard, light green and difficult to heal. Therefore, it is necessary to keep the scion in the dark during the period from leaving the mother to grafting. At the same time, we should also pay attention to the dullness of the grafting interface when grafting and dressing. In addition, when grafting, you should avoid weather periods with less light, such as rainy days and foggy days, because strong light is needed after grafting is completed. Because the scion has leaves, it can carry out photosynthesis under light conditions, produce assimilated substances and promote the germination of the scion. Strong light can make the scion water evaporate quickly, the temperature of the covering at the grafting place rises quickly, and the scion is easy to wither. The grafting survival rate is high under general shading conditions. Rain after grafting is not conducive to survival. In rainy days, there is no sunshine for a long time, which often leads to the growth of mold in callus or affects the survival of grafting.

4. Strong wind: When grafting encounters strong wind, the water on the surface of rootstocks and scions will be excessively lost, which will affect the healing and reduce the survival rate. When the new shoot grows to about 30 cm, stand close to the post with the height of 1 m ~ 1.5 m, and tie the new shoot to the post to prevent the strong wind from breaking the new shoot.

Second, the grafting method and pictures:

1, grafting: grafting a branch with several buds or 1 bud onto the rootstock is called grafting. The advantages of grafting are high survival rate and fast growth of grafted seedlings. When the rootstock is thick and the rootstock is not peeled, branch grafting is often used, such as patching the rootstock that has not survived the autumn bud grafting in spring. Root grafting and indoor grafting also use branch grafting. The disadvantage of branch grafting is that the operation technology is not as easy to master as bud grafting, and there are many scions, which require rootstocks of a certain thickness.

Common grafting methods include cutting, splitting, skin grafting, abdominal grafting and tongue grafting.

① Splitting: It is an ancient grafting method and widely used. It can also be used for thinner rootstocks (Figure 4- 10). Cutting the scion: cutting the scion into a wedge shape, with symmetrical sides of the section and a length of 3- 125px. The outside of the scion should be slightly thicker than the inside. If the rhizome is too thick and the clamping force is too great, the inner and outer thickness can be the same or the inner side can be slightly thicker to prevent the joint surface from being pinched. The cutting surface of scion should be straight and smooth, and the rough cutting surface is not easy to be closely combined. If one knife is uneven, one or two knives can be added to make the surface meet the requirements. Rootstock treatment: cutting or sawing the rootstock at the grafting site. The position of the kerf is very important, so the surface of the stump should be smooth and the texture should be straight, and at least there should be no scars on the top and bottom 150px, otherwise the split seam will not be straight and the xylem will split to one side. After selecting the grafting site and cutting it, split 1 in the center of the rootstock with a cleaver, so that the splitting depth is 3-3-100px. Connecting and binding: pry open the crack of the rootstock with a cleaver, gently insert the scion into the rootstock so that the thick side of the scion is outside and the thin side is inside, and then gently remove the cleaver. Pay special attention to the alignment of rootstock cambium and scion cambium when inserting. Generally, the cortex of rootstock is thicker than that of scion, so the outer surface of scion is slightly inward than that of rootstock, so that the cambium can be aligned with each other. The xylem can also be used as the standard, so that the surface of rootstock and scion xylem can be aligned and the cambium can be aligned. When cutting the scion, don't insert all the cutting surfaces, but expose the cutting surfaces of about 0. 125px. In this way, the contact surface between scion and rootstock is larger; But also beneficial to the formation and healing of meristem. A thicker rootstock can have two scions, one on each side. Then, tie it tightly with plastic strips.

2 cuts. This method is suitable for rootstocks with root neck 1-50px, which is a common method in branch grafting. Cutting scion: Scion is generally 5-200 px long, and three or four buds are suitable. Cut the lower part of the scion into two facets. The length of 1 is short, and the long facet is on the same side of the lateral bud. Cut off the essence above 1/3, about 75px in length, and cut a horseshoe-shaped inclined plane on the opposite side of the long facet, about 25px in length. Rootstock treatment: cut off the rootstock stem at 3- 100px above the ground. Select the thick, smooth and smooth part of the rootstock, flatten the cut surface of the rootstock, and then cut it straight down at the edge of the xylem. The width of the notch is the same as the diameter of the scion, and the depth is generally 2-75px. Connection: Insert the scion section inward into the rootstock incision. Align the scion with the cambium of the stock. If both sides cannot be aligned, you can align the 1 side. Binding: wrap it tightly with plastic, and wrap all cracks and open corners tightly. Be careful not to touch the scion when binding.

③ Tongue joint. Generally, the diameter of rootstock is about 1cm, and it is suitable for grafting when the thickness of rootstock spike is roughly the same (Figure 4- 1 1). Cut the back of the lower bud of the scion into an inclined plane with a length of about 75px, and then chop it up at 1/3 from bottom to top along the branches at the cut surface, with a cut of about 25px, which is tongue-shaped. The rootstock is also cut into an inclined plane with a length of about 75px, and the inclined plane is split down at L/3 from top to bottom along the rootstock, and the split mouth is about 25px, which corresponds to the inclined plane of the scion. Insert the split of the scion into the split of the rootstock, so that the tongues of the rootstock and the scion cross, then align with the cambium and insert tightly inward. If the thickness of the rootstock is inconsistent; The forming layer can be aligned to one side. After joining, tie it.

④ Skin grafting: This is the most easily mastered, the highest survival rate and the most widely used branch transplantation. It is required to be used when the anvil thickness is easy to peel. Garden tree cultivation has both high grafting and low grafting. Generally, the rootstock is cut off 5 ~ 8 cm from the ground, the cross section is leveled, and a longitudinal incision is made in the cortex of the rootstock in a smooth place, the length of which is 1/2-2/3 of the scion length. The scion is cut into a single inclined plane with a length of 3-4 cm, and the section should be straight and exceed the pith. The thickness is 0. 3-0.5 cm, and the back and end are cut into small inclined planes of 0. 5-0.8 cm, or slightly cut a knife on both sides of the back. When grafting, the scion is inserted from the rootstock incision along the middle of xylem and phloem, with the long section facing the xylem, and the back of the scion is aligned with the center of the rootstock incision, and the upper end of the scion is "left blank". If the rootstock is thick or the cortex has good toughness, the rootstock can be directly inserted into the cortex without cutting. Finally, tie it with plastic film strips.

⑤ Abdominal connection:

A. First, cut a long section with a length of 2 ~ 62.5 px at the lower end of the scion, and the end is as deep as 2/3 of the ear thickness. Then cut a short face on the back. The face is about short12.5px. Select the grafting part of the rootstock, and cut an oblique incision as deep as xylem 1/3, with a length and a long section. When inserting, the cambered surface on one side should be aligned and closely connected. Then tie it with plastic strips. After survival, grafted seedlings with straight trunk were propagated by cutting.

B, oblique abdominal scion cutting method as above. However, between the two sections, one side should be obviously thicker and the other side should be thinner, and then a knife is obliquely cut at the appropriate position of the rootstock to reach 1/3 of the xylem. The incision is deep outside and shallow inside, and the external depth should be equal to the long section of the scion. When cutting, the short section faces outward and the long section faces inward (thick side faces outward and thin side faces inward). The cambium is aligned with each other, closely connected and bound. This method is mostly used to fill the gap in the crown of a big tree, so the angle can be large, but the strong buds should be outward, and the anvil should not be cut after survival.

C, T-shaped abdominal joint: firstly, cut the scion with a long inclined plane with the length of 4 ~ 4~ 150px, and cut it as deep as possible until the lower end reaches about 4/5 of the diameter, and then cut a short inclined plane with the length of 12.5px on the reverse side. Select an appropriate part of the rootstock to cut through the cortex without damaging the xylem, and cut off another piece of old bark in a crescent shape above the transverse incision to facilitate the close connection between the scion and the rootstock. Cut a 1 ~ 50px incision vertically below the transverse incision, then insert the cut cuttings slowly and forcefully into the skin, and then tie them tightly with thin plastic strips.

⑥ Docking: Before docking, make the rootstock and scion close to each other, and then cut off some branches at the corresponding positions of the scion and rootstock, reaching 1/3 to 1/2 of xylem. The length of the joint depends on the diameter of the branch, which is generally about 4 times the diameter of the branch. Then, they were combined with each other, aligned with each layer, wrapped with plastic film, and healed one month after grafting. After grafting, the scion is cut from below the scion and the rootstock is cut from above the scion. Docking time can generally be used in the growth period. There are usually two ways to connect bonsai materials: one is to have a beautiful stump, but its variety is not good, so it needs to be connected with branches with good varieties. If you dig a wild crape myrtle pile, you can rely on the branches of Yin Wei. The other is a good variety of mother tree, which uses many seedlings as rootstocks and is taken from the mother tree. In the former case, scions can be butted with branches inserted in water bottles instead of seedlings. The latter is like the mother tree of pinnate maple, and many pinnate maple seedlings can be obtained by connecting the seedlings of green maple.

⑦ Root grafting: Branches with roots as rootstocks are called root grafting. Splitting, cutting and butting can be used. Rooting is often carried out indoors in autumn and winter, and rootstocks are collected in combination with nursery seedlings. Cutting scions: Rooted scions can be cut into cutting surfaces for splitting, cutting and butt joint. The cutting requirements are the same as those for division, cutting and butt joint. Cut the roots. Rootstocks should be collected and cut into thick1~ 2 ″ and long15 ″ rootstocks. The cutting method is the same as the splitting, cutting and grafting requirements of rootstock. Scions combine scions with rootstocks and bind them with materials that can be decomposed without unbinding, such as hemp skin, cattail and iris. , and sealed with mud, keep moisture. It is best not to use plastic strips to take root, because it will not degrade naturally and needs to be untied; If it is not untied, the plastic bandage will affect the growth. Then buried in wet sand to promote its healing, and planted after survival. Generally, it takes root indoors in autumn and winter. Such as peony grafting, using peony roots as rootstocks.

⑧ Bridging is a method of grafting, which is carried out in early spring when the trees just start to grow and the phloem is easy to peel off. Use species with strong affinity or the same tree species as scions. It is often used to repair big trees or ancient trees with bark injury but no root injury. Splicing spike: If there is sprout below the wound during bridging, it can be cut into horse ear inclined plane at the position where the sprout is higher than the upper part of the wound; If there are no new buds at the lower part of the wound, annual branches slightly longer than the upper and lower cuts of the rootstock can be used as scions, and a length of 125px which is the same as that of skin grafting can be cut at the upper and lower ends of the scion in the same direction. Rootstock cutting: removing injured, dead or torn bark, exposing healthy tissues at the upper and lower ends. Scion insertion: insert the scion above and below the wound, then nail the cut surface of the scion firmly with a small nail with a length of 37.5px, and then stick electrical tape or tie it tightly with plastic sheets at the interface to reduce water loss. If there are sprouts under the wound, only one end is connected, which is called one end; If there is no new bud under the wound, the two ends of the scion are inserted, which is called double grafting. If the wound is too wide, 2 ~ 3 or more scions can be grafted, which is called multi-branch bridging.

9. Grafting This method is suitable for young trees. Combine the connecting parts of rootstock and scion and tie them tightly. The thickness requirements of rootstock and scion are basically the same. Methods (1) The rootstock was cut about 10 cm near the ground, and then cut into inclined planes. (2) Selecting a scion with the same thickness as the rootstock, and cutting the lower end of the scion into an inclined plane with the same angle and length as the rootstock. (3) Stick the inclined plane of the scion and the inclined plane of the rootstock together, and then tie the joint tightly with a strip-shaped plastic film without leaving any "tuyere".

2, bud grafting:

① "T" bud grafting: Because the incision of rootstock is very similar to "T", it is also called "T" bud grafting. Because the cut bud is shield-shaped, it is also called shield-shaped bud grafting. T-bud grafting is a grafting method widely used in fruit tree seedling, and it is also a method with simple operation, fast speed and the highest grafting survival rate. Bud length1.5-2.1.25px, width 0. 150px. The diameter of the rootstock is between 0.6-2.1.25px. If the rootstock is too thick, the bark will become thicker, which will affect the survival. The specific operation is shown in Figure 4-4. Bud cutting: Select the complete bud on the scion, first cut the L knife at 12.5px above the bud, and cut through the cortex. The transverse incision is about 20px long. Then obliquely cut 1 knife upward at the position of 1-30px under the bud, from shallow to deep, go deep into the substantive part, and intersect with the transverse incision on the bud. Then use your right hand to pick the shield-shaped bud. Rootstock opening: When the rootstock is 5- 150px from the ground, choose a smooth and unbranched place to cut 1 knife, and the depth is appropriate to cut off the cortex and reach the xylem. Then cut 1 knife vertically downward in the middle of the transverse incision, with the length of1-37.5px. Connection: pick up the cortex of the rootstock with a bud grafting knife, insert the bud grafting into the T-shaped incision, and make the transverse incision of the bud grafting align with the transverse incision of the rootstock and embed it. Bind: Bind with plastic strips. First punch one above the bud, then punch one below the bud, and then circle it three or four times to tie the hook. Pay attention to exposing the petiole and whether there are buds.

② Grafting: For tree species with angular or furrowed branches, such as chestnut, jujube, or rootstocks and scions of other plant materials, grafting method can be adopted. With a knife, the 1 knife was cut downward at the position of 0.8- 1 cm above the scion bud, and it went deep into the xylem, with a length of about 37.5px, and then it was obliquely cut at the position of 0.5- 15px below the bud, and then it met with the cut of 1 knife at an angle of 30, and the inverted shield-shaped bud piece was taken off. The incision of rhizome is slightly longer than that of bud. After the bud is inserted, it should be noted that the upper end of the bud must be exposed to the L-series rhizome cortex. Finally, tie it with plastic strips.

③ Other budding methods.