(1) Branch grafting method: For Sophora japonica with thick main branches, branch grafting or split grafting can be adopted. Select annual branches from the scion, and collect the scion of Sophora japonica after the first autumn of grafting. The length of the scion is10 ~12cm, the thickness is 0.4 ~ 0.6cm, and each scion has 3~4 buds. Then, the scion was immersed in paraffin dissolved at 60~80℃ at a medium speed, so that the surface of the scion was covered with a thin wax film. After soaking in wax, bundle them into bundles, put them into plastic bags, and put them into pits or bunkers. If stored in refrigerator or freezer, germination can be extended to the suitable grafting period of the next year. The next spring, when the sap began to flow, it was grafted or split. In warm climates, scions can also be used for grafting. The specific grafting method is as follows: first, cut a knife on the back of the first bud of the scion, 2~3 cm away from the bud, and cut an inclined plane about 2 cm long, then cut a knife on the opposite side and cut it into a wedge shape. At the top of the prepared rootstock, cut vertically downward, and there is a slight xylem inside the cambium, which is equal to the length of the scion. Insert the scion into the rootstock, aim at the cambium on both sides or one side, and tie it tightly with hemp skin or plastic strips. Each plant should be grafted with 3~5 scions to form a crown as soon as possible. After 20 days' inspection, the scion germinated and survived. After survival, pay attention to erasing the new buds of the rootstock to promote the growth of the scion. If there is no survival, leave 3~5 strong roots and buds for budding in May ~ June.
(2) Bud grafting method: the time is May-June, and the rootstock is Sophora japonica, which does not survive in spring. In the spring of the second or third year of the trunk of Sophora japonica, when the cambium of the tree is active and can be peeled off, dormant buds are taken from the last branch of Sophora japonica and grafted on the annual to biennial main branches of Sophora japonica. The grafting site should be within 30 cm from the trunk, and the bud should be grafted above the branch. Each main branch should be connected with a bud, and each plant should be connected with 3~4 evenly distributed main branches. The specific method of bud grafting is: first, cut off the leaves on the scion, leaving a little petiole, and cut the bud into shield-shaped buds about 2 cm with the bud as the center, without xylem. Cut a T-shaped knife edge on the cut rootstock branch, which is as deep as the xylem and the same size as the bud. Pick with a knife and embed the bud. The upper end of the bud is next to the cross section of the rootstock and tied tightly with hemp rope or plastic strip. 10 days later, check whether the scion is alive. If the petiole of the scion falls off as soon as it touches, it is proved to be alive, otherwise the grafting fails.
(3) Socket method: Besides bud grafting, the survival rate of socket method is also high. Select the vigorous branches of Sophora japonica as scions, cut off the leaves, and then "twist" them from the base, that is, separate the tree epidermis from the xylem, cut them off when twisting them to 4-5 cm, extract the xylem, immediately cut off the buds with the same thickness of the pre-selected branches of Sophora japonica rootstock, peel them from the top, and put on the scion tube. After peeling, leave 0.5cm wide rhizome peeled, and the extra Pi Zha is on the tube. No matter whether it is branch grafting or bud grafting, after 1 month, the core should be picked and the new shoots of the rootstock should be smoothed. In the daily management, the branches that grow vigorously after grafting are pruned to form an ideal crown. When grafted seedlings are young, attention should be paid to the prevention and control of aphids and inchworms.