Several common methods of walnut grafting

There are many grafting methods of    walnut, which can be divided into two types: branch grafting and bud grafting according to the grafting time and the type of grafting. The method of grafting with a piece of budded branches is called grafting, while those with only one bud as grafting are called budding.

The common grafting methods of    are split grafting, tongue grafting, skin grafting, ventral grafting, etc., and budding methods include square bud grafting, T-shaped bud grafting, ring bud grafting, I-shaped bud grafting and so on. Square bud grafting is the most commonly used method for mass propagation of seedlings at present, and branch grafting is mainly used for height grafting of big trees or replacement of buds in the second spring when they did not survive.

   1. Cleavage in the northern region is mostly carried out from late March to late April after bud germination to leaf expansion. Select the rootstock with a diameter of more than 2 cm, cut or saw it off about 10 cm from the ground, cut the saw blade, split it in the middle of the rootstock with a splitter knife, about 5 cm deep, and the scion is wax sealed, leaving 1 inch 3 bud eyes. cut a slope of 3 cm to 5 cm on each side of the corresponding side of the first bud, and the two sides are equal in length. Insert the splice into the split rootstock seam, so that the base of the cutting surface of the joint is exposed a little, such as a semilunar shape. Be careful to align the rootstock with the cambium of the scion. When the thickness of the rootstock and ear is the same, the cambium on both sides can be aligned, the rootstock is thicker, and the scion should be thinner to align the cambium on one side, and then bind tightly with plastic strips. The time of branch grafting is very critical, generally less bleeding and high survival rate after leaf spreading.

   grafting should pay attention to the grafting can not be loosened, even if the hand is not easy to shake, beginners often bind lax, often cause grafting failure because of scion loosening. The main reason for the loosening of the joint is that the angle of the cutting surface is not consistent with that of the opening of the rootstock, and the other is that the cutting surface is uneven. The cutting angle of the cutting surface is large, so that the front end is not clamped tightly; the cutting angle of the scion is small, so that the rear clip is not tight, so the angle of the cutting surface needs a lot of practice to master. In addition, the misalignment of cambium is also one of the reasons for the failure of grafting.

   2. Cut off an epidermis from the bottom to the top after sawing the rootstock. It is 5 cm 7 cm long and 1 cm 1.5 cm wide, exposing the degree layer and cutting a knife longitudinally in the middle. The scion was cut into a single cutting surface of 6 cm to 8 cm, showing a Malal shape, and the degree layer behind the cutting surface was pinched by hand to separate it from the wood. the xylem of the cutting surface was inserted into the rootstock between the xylem and the cortex, and the cut surface of the rootstock was covered with the crushed skin, and finally tied tightly with plastic sheeting. The spring joint does not leave the skin, so it is difficult to pinch it, so the joint with the tongue should be awakened in advance to make it off the skin. Methods the germination of the same seeds, pay attention to grasp the time of treatment, awakening time is too long will make the grafting germination, resulting in the survival rate of grafting decreased. The skin grafting method is a little more cumbersome, but it is the method with the highest survival rate of walnut branch grafting.

   3. Skin grafting, also known as subcutaneous grafting, is a method with a high survival rate in branch grafting. It must be carried out after the stone rootstock is "peeled" (that is, the cambium begins to move). After sawing or cutting off the rootstock, the saw is flattened, and the smooth part of the rootstock is cut vertically from top to bottom, reaching to the xylem, and the length is as long as the cutting surface. At the same time, use a knife to lift the cortex to both sides. The cutting surface is in the shape of a horse ear, 6 cm long and 8 cm long, and then gently cut a small bevel at the back end of the cutting surface, 0. 5% long. 5 cm, can also be cut left and right west knife, showing two small bevel, easy to insert scion. The wax layer and cortex on the back of the cutting surface can also be gently scraped off with a knife to expose the white and green phloem, which can increase the contact surface, facilitate the transport of water and nutrients, and promote the formation of callus.

After the    was cut, it was inserted into the small mouth of the rootstock, and the base of the cut was white, showing a semilunar shape. Finally, it was wrapped in plastic sheeting. It is widely used in production because of its large contact surface and high survival rate of grafting. However, after the grafting survived, the mechanical bearing capacity of the callus of rootstock and anchovy was poor, and it was easy to be broken by wind after germination, so it needed to be supported in time.

Matters needing attention for    branch grafting: a be careful not to irrigate before grafting, sawing off stone wood 3-5 days before grafting or opening several water outlets spirally at the base of the trunk during grafting, so as not to affect the survival rate of grafting. B the grafting time should be selected, because the production of callus requires a certain temperature range, and the optimum temperature is about 26 ℃. Branch grafting should be carried out from sprouting to leaf spreading in spring.

   4. Square bud grafting this method has a high survival rate and is the most widely used walnut grafting method in recent years. The specific method of operation is to leave the petiole 0. 5% with a knife. Cut off about 5 cm, cut a knife 1 cm above and below the bud, and 0. 5% on both sides of the petiole. Cut a knife vertically at 5 cm, intersect with the crosscutting edge, press and hold the petiole with thumb and index finger to peel off horizontally, take off a rectangular bud piece, and pay attention to a small piece of bud tissue at the base of the bud inside the growing point. Cross-cut a knife in the smooth part of the rootstock about 20 cm from the ground, and then cross-cut another knife above the blade, and the distance between the two knives is equal to the length of the buds. One end of the two horizontal blades is vertically cut, which is connected with the upper and lower horizontal blades. Open the "door" of the cortex and put it into the buds. On one side, close to the vertical knife edge, tear off the raised rootstock bark according to the transverse width of the buds. Note that the skin removed is slightly wider than that of the grafted buds. So that the budding and cambium can be closely combined. Cut the thick plastic film into plastic strips 3 cm wide for binding, and pay attention to the tight cross-section of the petiole to expose the bud point. Finally, two compound leaves of the rootstock above the interface were cut off with pruning shears to control the vegetative growth of the rootstock and be beneficial to the survival of bud grafting. Square bud grafting should be carried out from the end of May to the middle of June, and the bud can germinate into seedlings in the same year. Some of them were grafted from July to August, but the grafted buds did not germinate in the same year (stuffy buds), and then cut the rootstock and germinated into seedlings in the second year, which was mainly used for the supplementary grafting of rootstocks that did not survive from May to June.

The rootstock cutting method of    square bud grafting also has open zigzag mouth, which is called I-shaped bud grafting. The scion cutting method is the same as square bud grafting, the rootstock is cut twice horizontally, and when cutting vertically, cut one knife in the middle of the two crosscutting edges, pick the cortex of the rootstock to both sides, put it into the bud and bind it. I-shaped buds can not remove the excess skin, this method is also known as open the door.

   is used to grafting with a double-edged knife in some places, which is easy to operate and has a high survival rate. You can make a double-edged bud splice knife by yourself. Take two 10cm long hacksaw blades and grind the blade with a grinding wheel. Find a small wooden strip with a width of 4cm, a thickness of about 1cm and a length of 10cm. Tie the knife made of the saw blade to the wood blade with cloth strips. The grafting operation is similar to the single-edged knife, except that the two cross-cutting knives are completed at one time, and it is easy to make the incision of the rootstock equal to the length of the buds, which can improve the grafting speed and the survival rate.