Walnut grafting is an important factor restricting the process of improved walnut varieties. At present, the mature grafting methods are nothing more than indoor double tongue grafting, skin grafting and square bud grafting. However, these methods also have their own advantages and disadvantages: indoor double-tongue grafting in winter requires a series of complicated operation processes, such as building a greenhouse, awakening rootstock seedlings, laying a ground hotline, controlling temperature, transplanting seedlings after survival and so on. It is labor-consuming, time-consuming and laborious, and it greatly increases the cost of finished seedlings, so that the price of grafted seedlings remains high; After leaf spreading in spring, tongue grafting requires a greater thickness of rootstock, which is generally used for grafting rootstock and trees with a thickness of more than 3 cm. It also needs procedures such as draining rootstocks, filling scions, bagging, windbreak, unpacking, etc., which is labor intensive and the survival rate is not ideal. It is a good method to apply square bud grafting in summer, but it wastes scions, and the hot weather is not conducive to work. When taking buds, vascular bundles (growing points) are easy to fall off, which affects survival. After grafting, it is necessary to cover the rain and bundle, which affects the grafting speed and is not conducive to the mass reproduction of finished seedlings. Bud grafting is a relatively simple and easy-to-learn new method of walnut grafting, which was obtained through two years of experiments. Its survival rate is over 95%, which not only saves labor, but also greatly improves the grafting speed. This is a good method worth popularizing. The following is a detailed introduction:

1, scion collection: from mid-March to before germination, select high-quality walnuts such as Liao 1, Xiangling, Jinlong 1, Jinlong No.2 and Qing Xiang. Collect full, robust and pest-free annual branches at the periphery of the crown, then dig a ditch with a depth of 80cm and a width of 50cm (the length depends on the number of scions) in the shady and shady place, and then hide the scions in the ditch for later use according to the method of wet sand layer by layer, and the last scion is about 30 cm away from the ground, so as to prevent the ground temperature from being too high and promote bud germination.

2. Grafting time: The best grafting time is that the rootstock seedlings grow to about 3㎝, which generally starts in mid-April and ends in late April.

3. Requirements for rootstock seedlings: 1-2-year-old seedlings or seedlings in nursery; It can also be used to change the head of a tree before the first fruit.

4. Grafting site: robust 1 annual branches around the crown.

5. Grafting method: Before grafting, the rootstock does not need to be drained. When grafting, the rootstock should be cut off at the appropriate annual grafting site (only the annual rootstock seedlings should be cut off to 15-20cm). When cutting buds, the left hand will turn the scion upside down, and the right hand will cut it down to 1.5 cm below the bud with a knife. The bud piece should have a part of xylem, and the thickness of the grafted bud should be about 2 mm, and then a knife should be cut under the bud 1.5 cm to remove the bud piece. The cutting method of the rootstock is basically the same, that is, cut down about 3cm (or slightly longer than the length of the budding) at 2-3cm below the cutting edge of the rootstock, then cut the peeling block horizontally with a knife, then quickly stick the budding on the cutting surface, align the lower end of the budding with the cutting edge of the rootstock, and then tie the plastic cloth tightly. It should be noted that the width of the plastic cloth strip is 2 cm, and the bud should be exposed. It should also be noted that the rootstock should be shaved off just after the xylem is exposed. Pay attention to rapid grafting to prevent browning of bud grafting and rootstock interface.

Generally, the grafted buds can germinate about 15-20 days after grafting. At this time, the sprouting branches and buds of the rootstock should be erased in time. When the height of grafted seedlings is 15-20 cm, the plastic sheets can be untied and sticks erected to prevent the seedlings from being broken by the wind.

Walnut seedling technology: seed collection: select tree species with strong adaptability and vigorous growth as planting trees, such as Xinjiang thin-shell walnut, wild walnut, and popularize high-quality walnut. When the exocarp of walnut fruit changes from green to yellow (or yellow-green), it will be harvested when the whole tree cracks about 50%. Seed sand storage: Choose a storage pit with high terrain, good drainage, shelter from wind and shade, with a width of 1.0- 1.5m and a depth of 0.7- 1.0m, and the length depends on the storage capacity. The bottom of the pit is covered with a layer of wet sand with a thickness of about 10cm, and the humidity is at the level where hands are folded but no water comes out. Scatter the seeds on the sand, and fill the pits and walnuts with wet sand, leaving no gaps; Put a layer of seeds on another layer of sand, so when it is buried to a distance of 10-20 cm, cover it with wet sand to make it flush with the ground. The sand is ridged, wider than the pit, and there are drains around it. The suitable time for sand storage of seeds is about 80 days, and the seeds should be soaked in cold water for 2-3 days. Qin Ying should check during sand storage to prevent the seeds from becoming moldy. Soil preparation before sowing: the nursery was deeply ploughed twice in autumn and winter of the previous year, with a depth of about 30cm, and sundries were collected. Apply organic fertilizer per mu 1500-2000 kg, level the border before sowing, and the width of the border1m. Sowing: Sowing should be carried out when the soil temperature reaches above 65438 00℃ after thawing in spring, preferably from late March to early April. Seedbed width 1m, sowing in three rows, row spacing of 30-40cm, plant spacing of 10- 15cm, and soil covering of 5- 10cm after sowing. When sowing, the suture line of the seed should be vertical to the ground, and the tip of the seed should be biased to one side. Other placement methods will lead to the bending growth of young roots or young stems, and the emergence of seedlings will be slow. Cover with plastic film immediately after sowing. Seedling management: timely check seedlings for replanting, intertillage and weeding. Topdressing 1 times of effective nitrogen fertilizer before July after the seedlings grow completely, and topdressing 1 times of effective phosphorus and potassium fertilizer from July to August. Water the seedlings after they come out and after fertilization, but don't water them before they are unearthed. Do a good job in the prevention and control of pests and diseases at seedling stage.

You can contact me, Zhang, Fruit Tree Station of Yixian Forestry Bureau, Hebei Province. First of all, I introduced my published paper: a new technology of walnut grafting-bud grafting.