Key Points and Detailed Operation Methods of Chestnut Tree Grafting Techniques

"Transplanting flowers onto a different tree" was originally a derogatory term, a metaphor for secretly using means to swap people or things in order to deceive others. But in the world of plants, "transplanting flowers onto a different tree" can only be described as a good path for development and innovation. There are two ways to propagate chestnuts: one is to cultivate saplings, and the other is grafting propagation.

Chestnut Tree Grafting Techniques

1. Grafting time. Carry it out from late May to early June, over a period of about 15 days.

2. Scion selection and rootstock pruning. Select nutrient shoots from the sun-facing spring shoot section on the outer middle-upper part of a robust mother tree that has borne fruit for many years with high and stable yield and excellent quality. They should be well developed, with prominent and relatively plump buds, shoot length of 25-30 cm, and shoot diameter of 0.8-1.2 cm. The scions should be used as soon as they are collected and must not be kept for long. Cut off densely grown and improperly positioned branches on the rootstock from the base, leaving 4 branches of basically uniform size that grow obliquely in four directions, with a branching angle of 45-50 degrees. The lowest branch should be 30-40 cm above the ground, and each branch should be cut back to a length of 40-50 cm. All leaves on the rootstock should be retained. Below the cut of each grafted branch, keep only 1-2 small branches as auxiliary nourishing branches, and cut off all other small branches from the base.

3. Main technical steps of grafting. ① Cutting the graft bud: Cut the leaves off the scion from the base, leaving the leaf stalks, but do not rub them off by hand, so as to avoid leaving leaf scars and causing wounds on the scion. Then cut off both ends of the scion, leaving 3-4 relatively plump buds in the middle for single-bud cutting. Cut the graft bud into a decapitated bud and graft it using the single-bud cleft grafting method. The cut graft bud should be grafted immediately and must not be left for long, nor does it need to be soaked in clean water.

② Plastic film wrapping: Choose plastic film with a specification of 3 mm, moderate thickness, good toughness, easy to handle and not easy to tear, so that it ties firmly. When wrapping, pay attention to exposing the bud eye.

4. Post-grafting management. After grafting, check once every 3-5 days and remove sprouts growing from the rootstock as early as possible. When the graft bud sprouts, cut off the auxiliary nourishing branches from the base and manage the new shoots well. Notes for new shoot management: ① When the new shoots are about 15-20 cm long, pinch off the growing tips to promote branching.

② Because summer shoots have sufficient nutrients, with long shoots and large, luxuriant leaves, strong winds and heavy rain can easily break the new shoots, so small sticks should be used to tie and secure the new shoots.

③ When multiple new shoots sprout, remove the weak and keep the strong, remove the oblique and keep the straight, to accelerate healing of the graft union.

④ Control pests and diseases such as inchworms, flea beetles, and powdery mildew that harm the new shoots.

⑤ To supplement the plant's nutrition and help strengthen the shoots, apply additional fertilizer 1-2 times, with 100 g urea plus 150 g compound fertilizer and 2.5 kg organic fertilizer per plant, applied in a shallow ring-shaped trench after rain. The first additional fertilization is at the stage when the new shoots turn green, and the second is at the stage when the secondary new shoots sprout.

⑥ For unbinding, it is advisable to remove the tied plastic film about 10 days before sprouting in the spring of the second year. At the same time, continue to remove the rootstock suckers growing from the rootstock.

Growth Habits of Chestnut Trees

Chestnut has a relatively wide range of adaptability to climate and soil conditions. Its suitable annual average temperature is 10.5-21.8°C. If the temperature is too high, dormancy is insufficient and growth and development are poor; if the temperature is too low, it is prone to freezing damage. Chestnut likes moist soil, but it also fears the effects of waterlogging. If rainfall is excessive and the soil is waterlogged for a long time, it can easily affect root growth, especially mycorrhizal growth. Therefore, chestnut orchards should not be developed in low-lying, easily waterlogged areas.

Chestnut is relatively sensitive to soil pH and is suitable for growing in slightly acidic soil with a pH value of 5-6. This is because the chestnut tree is a manganese-loving plant, and under acidic conditions, nutrient elements such as manganese and calcium can be activated, which is beneficial to the absorption and utilization of chestnuts. The Xuzhou area is located at the southern edge of the Huangtan Sea, with an annual average temperature of 13.7-14.1°C and annual precipitation of 782-946 mm, suitable for the growth and development of chestnut trees.

Chestnut Planting Techniques

1. Orchard site selection: A chestnut orchard should choose sandy loam soil with a relatively low groundwater level and good drainage. Avoid planting in places with saline-alkaline soil, low humidity and easy waterlogging, or strong winds. When opening a chestnut orchard on hilly and mound land, choose a gentle area near mountains with a thicker soil layer, and later it can gradually be expanded to areas with poorer conditions.

2. Variety selection: Variety selection should mainly use excellent varieties bred locally, such as Paoche No. 2 and Chenguo No. 1, and appropriately introduce varieties such as Shifeng, Jinfeng, Haifeng, Qingmao Ruanci, and Chushu Hong. According to different edible requirements, mainly use chestnut varieties for roasting, and appropriately develop excellent varieties for cooking chestnuts, taking into account both foreign trade exports and domestic market demand. At the same time, achieve a reasonable mix of early, middle, and late varieties.

3. Pollinator tree configuration: Chestnut trees mainly rely on wind to spread pollen, but because chestnut trees have the phenomena of female and male flowers maturing at different times and self-pollination, a single variety often produces empty burs due to poor pollination. Therefore, a newly built chestnut orchard must be configured with 10% pollinator trees. Practice has proved that using Chushu Hong as a pollinator tree in Xinyang City is better.

4. Reasonable close planting: Reasonable close planting is a basic measure to increase yield per unit area. For plain chestnut orchards, 30-40 trees per mu is suitable, and for mountain chestnut orchards, 40-60 trees per mu is suitable. For planned close-planted chestnut orchards, 60-111 trees per mu can be planted, and later thinning can be carried out gradually by alternate rows and alternate trees.

When Do Chestnuts Ripen

Chestnuts ripen roughly between September and October. There are many varieties of chestnuts, and different varieties differ somewhat in their ripening periods, but most ripen in autumn. The flowering period of chestnuts is usually from May to June, and the fruiting period is from September to October. In some areas, chestnuts have already ripened and gone on the market in mid-to-late August, but generally all chestnuts ripen before November, and eating seasonal chestnuts in autumn is the most delicious and nutritious.

Grafted chestnut saplings require more careful care. Compared with the planting method of cultivating saplings, grafting requires a shorter waiting time. It is a good way to bring forth the new from the old, not only helping old chestnut trees regain new vitality, but also creating conditions for the production of new chestnuts.