Common methods of abdominal grafting of Chinese chestnut in Yanshan

Common methods of abdominal grafting of Chinese chestnut in Yanshan

The grafting of Chinese chestnut can improve the survival rate by means of ventral grafting, ventral grafting, ventral grafting with basal branch, bare column and so on. It has been widely used in Yanshan chestnut producing area with good results.

1 collection and treatment of scion

1.1 collecting scion

Scions should be collected from large trees with good varieties and strong growth in full fruit stage, and annual developmental branches or fruiting mother branches with good development, full tissue, full bud and sturdy buds should be cut from the mother tree. It is best to collect within one month before germination (around the Spring Equinox in mid-late March). The storage period is not more than 50 days, otherwise the survival rate of grafting decreases; the longer the storage time, the lower the survival rate of grafting. For more than 80 days, grafting is generally not easy to survive.

After harvest, the scion should be arranged as necessary, cut off the unsubstantial part of the front part of the branch and the blind segment and the curved part of the base of the fruiting branch in the current year, the length of the scion is more than 20 cm, and the thickness is more than 0.6 cm. After collection, 50cm and 100 roots are bundled together to mark the varieties and store them in a cellar with low temperature and moisture in time.

1.2 Storage of scions

When the number of scions is small, it can be stored in cellars or caves, and sealed, and the ground is shaded by straw to prevent heating, the temperature is not more than 10 ℃; it can also be put in wells, more than 1 meter from the water surface, covered with well covers; it can also be put in the freezer of household refrigerators; when the number is large, it can be stored in cellar, ditch storage or cold storage.

1.3 scion wax seal

In order to prolong the preservation period and improve the survival rate of grafting, the scion can be sealed with wax. First cut the scion into the length required for grafting, generally 10-15 cm (with 2-3 full buds), the thick one can be longer and the thin one can be shorter. The industrial paraffin wax is then melted in a container (preferably using a water bath type sandwich bucket to facilitate the control of paraffin temperature), and the temperature is controlled at 80 to 100 ℃. After paraffinization, take one end of the scion and dip it in wax, and take it out immediately, the faster the better (impregnate for 1-2 seconds). Then change the other end and then dip it, do not leave the gap between the undipped wax, so that the whole scion is covered with a uniform paraffin layer. After the wax-sealed scion is fully cooled, tie it up and put it in a gunny bag or plastic bag (for a longer storage time, put it in a plastic bag) and put it in a cool place. After marking, sand storage or refrigerated reserve, the scion should be fresh, water-rich, non-sprouting, no mildew rot, no freezing damage.

2 grafting period

Generally from late April, as long as the preserved scion does not sprout, the grafting period can last until the end of May, but when the rootstock sprouts and leaves have not yet spread, it is the most suitable. When the temperature rises again, the daily average temperature is more than 15 ℃, and the new buds grow to 0.5cm. When the leaves are not yet unfolded (when the local peach blossoms are in full bloom), grafting is the best.

3Graft method

Fig. 1 cut the belly of Chinese chestnut

3.1 abdominal grafting

When the rootstock does not leave the skin, it can be carried out. The method is simple and the survival rate is high (figure 1). It is mostly used to fill the vacant part of the tree crown, so the angle between the scion and the rootstock can be appropriately increased to make the strong bud outward, extend laterally after forming branches, expand the crown, and do not cut the rootstock after survival.

3.1.1 the cutting of the rootstock should be at an appropriate height and choose the smooth side. In the pre-grafting part of the rootstock, a deep cut is made oblique from top to bottom, and the incision goes deep into the xylem, but the lower end of the incision should not exceed the pith, which is the depth of the xylem. The cut is deep outside and shallow inside, and the length of the incision is equal to the length of the scion.

3.1.2 cutting scion ventral scion is suitable for slightly longer, thicker and slightly curved scion. Select the one-year-old strong growing branch as the scion, cut the scion into a partial wedge, use a knife to cut a long cutting surface of 3 cm to 5 cm in length at the bottom of the scion, and the cutting surface should be straight and inclined. Then cut the short cutting surface of 1.5 cm to 2.5 cm on the back of the long cutting surface to make the lower end slightly sharp, the two cutting surfaces should be slightly thicker on one side and thinner on the other side, the top buds should be left with 2 or 3 full buds in the upper part of the scion, and the apical buds should be left on the back of the large cutting surface, and the cutting surface must be smooth. 0.5 cm above the bud.

3.1.3 quickly cut the scion short facing outward, long cutting inward (thick side outside, thin side inside), insert the cutting incision of the rootstock, and pay attention to ensuring that the cambium of the rootstock and the scion are aligned and closely connected with each other.

3.1.4 after binding, wrap it tightly with plastic strip to keep it moisturized.

3.2 subcutaneous ventral grafting

When the rootstock is peeled, it is mainly used to repair the bald inside the chestnut tree. The survival rate is high, and it can also be used for high connection and replacement, using the front living strut for new binding, and then cutting off the living strut later.

In the part where the rootstock needs to be mended (usually one branch every 75cm to 100cm), the old skin of the rootstock is thinned to the fresh phloem, then cut a T-shaped opening, at the upper end of the transverse incision 1cm to 2cm, with a grafting knife downward, cut a crescent oblique cutting surface, to the T-shaped transverse incision, deep to the xylem, so as to avoid "cushion" after the scion is inserted. If the bark of the rootstock is too thick to use a cut scion to hard insert the cortex of the rootstock, you can first insert it with a hard bamboo stick to tilt up the incision cortex of the rootstock.

The scion should be longer, usually about 20 cm. It is best to choose a curved scion, with a Malt shape with a length of 8 cm to 12 cm, and an arrowhead on the back to the phloem; then insert the scion into the cortex of the rootstock and wrap it tightly with plastic strips without exposing the wound (figure 2).

Fig. 2 process of subcutaneous ventral grafting

3.3 ventral grafting with basal branch

In fact, it is a new method for the improvement of subcutaneous ventral connection, which has the advantages of natural opening of the base angle, large angle, above the "T" mouth of the rootstock, no need to cut the crescent knife edge, and do not have to worry about the problem of "pillow". The specific methods are:

The old skin of the rootstock is thinned, and the rootstock that does not form an old warped skin does not need to be cut, directly cut a T-shaped incision in the selected part, deep into the xylem. The scion selected two 1-year-old branches on the 2-year-old mother branch, left 3 cm on the 2-year-old mother branch, selected one 1-year-old branch on the branch and left it as a scion, and the other branch was cut 2 cm away from the branch. the cut branch can also be used as a bark graft for other chestnut trees. Then, from the shears leaving 1-year-old branches down to 2-year-old basal branches cut into horseshoe shape, 1-year-old branches are thick and 2-year-old basal branches are thin (the knife direction is a section of 1-year-old branches left behind).

The cut 1-year-old scion with 2-year-old basal branch was directly inserted into the T-shaped mouth of the rootstock and wrapped with plastic strip, the survival rate was high and the effect was good.

3.4 bare post skin graft

The naked column ventral grafting method of Chinese chestnut is to leave 50 cm in front of the grafting interface when the chestnut sprouts and peels off in spring, and the bark is stripped off with pliers to make a fixed pillar, and then the scion is grafted on the rootstock with bark grafting. It is suitable for the chestnut orchard with the technology of "happy, pulling branches, carving buds".

This grafting method can avoid the significant effect of tree bleeding on the callus formation of grafted trees and improve the survival rate of grafting. The sprouting shoots are directly tied to the fixed strut, which can avoid the occurrence of strong wind injury and broken branches. After the bark was stripped off, the branches in front of the interface died, which reduced the ineffective consumption of nutrients, which was beneficial to the robust growth of the main and lateral branches, and the interface healed well.

3.4.1 the rootstock is peeled at a distance of about 20 cm from the trunk (select a smooth position on the inside of the main branch), and the bark is stripped off with pliers above the interface, leaving 50 cm as a fixed living pillar.

3.4.2 the length of the cutting surface of the scion is 5 cm 8 cm, and the length of the ear is 7 cm 10 cm, which ensures that there are 3% 4 full buds.

3.4.3 choose a smooth position on the inside of the main branch (to prevent the branch from breaking), pry open the cortex and insert the scion quickly. The rootstock of young trees is thin, and only one scion is inserted at an interface, so don't get too much.

3.4.4 A special plastic strip for grafting is used to bind the interface tightly and fasten the buckle (later untie the plastic strip and be used to bind the new tip) (figure 3).

3.4.5 Anti-moth uses flour to boil into a dilute paste, and then add strong-smelling organophosphorus insecticides (quick-killing or dichlorvos, etc.). The paste sticks to the branches for a long time and plays a role in repelling pests. The wrapped plastic strip is coated with a layer to prevent the adults of Castanea mollissima from laying eggs and larvae eating the interface through the repellent effect of pesticides on pests. At the same time, it is also effective for other pests. It can also control the spread of carcass blight (figure 4) [Jishan Huayao].

Fig. 3 ventral grafting of bare column

Fig. 4 paste after connection to prevent diseases and insect pests