Grafting Methods of Chinese Chestnut Grafting Propagation (Ⅰ)

There are many grafting methods for Castanea mollissima seedlings, mainly as follows:

1. Split method

It is used when the scion and rootstock are not separated from the skin before sprouting. The thickness of rootstock should be 1 cm ~ 2 cm. The lower part of the wax-sealed scion is wedge-shaped, and the length of the two sides is the same, about 4 cm. And make one side of the cutting surface slightly thicker and the other side slightly thinner. The knife should start from 0.5 cm away from the lower bud to avoid damage to the lower bud. Hold the lower part of the cut scion in the mouth to reduce the oxidation of the cutting surface. Then cut the rootstock at 5 cm ~ 10 cm from the ground, choose the straight side, and use the grafting knife to cut all the openings vertically in the center of the section, about 5 cm long. Insert the scion thickness outward and thin inward into the notch to make sure that the thick cambium is aligned with the rootstock cambium. The upper end of the cutting surface of the scion should be 0.3 cm higher than the cross section of the rootstock to facilitate the production of healing tissue. Then tie the grafting site tightly with a plastic strip (black is better) to secure the scion and prevent water evaporation. This method has exuberant seedling growth and strong wind resistance, but the survival rate is slightly lower than that of subcutaneous grafting.

2. Splicing method

The rootstock is used when the rootstock is not separated from the skin, which is generally suitable for small rootstocks with a diameter of less than 1.2 cm. First cut the rootstock where it needs to be grafted, and then split a vertical cut with a grafting knife from the diameter of 1 to 3, about 4 cm long. The scion was cut into two cutting faces, the length of the long cutting surface was the same as that of the rootstock, the short cutting surface was about 1 cm long, and the scion had 2 ~ 3 buds. Insert the large cutting side inward into the split of the rootstock, align one side of the cambium of the rootstock, and tie the grafted part tightly with plastic strips. The bandage of this method is more strict than that of split grafting, and the wind resistance of seedlings is worse than that of split grafting.

3. Subcutaneous grafting

Also known as skin grafting. It is suitable for the thicker rootstocks with the thickness of the grafting site more than 2 cm, and the buds of the rootstocks are easy to leave the skin. First, select smooth and scar-free branches where the rootstock needs to be grafted, cut off the rootstock and flatten the cross section. Use a bamboo stick to insert 3 cm at the cambium of the scion to be inserted and pull out the bamboo stick. Then cut the scion with a Maltese-shaped surface about 4 cm long, and the back part is thick and the front part is thin, so that there is little xylem left at the front end. Cut the scion inward and insert it into the predetermined position. Do not insert all the cutting surface into the cortex, leave about 0.3 cm above the cross section. Then the grafted site is tightly bound with plastic strips. The survival rate of this method is high, the seedling growth is exuberant, but the resistance to wind is poor. After the new shoot of scion grows to 30 cm, it is easy to break from the grafting site in case of wind.