The Latest Cultivation Techniques and Methods Tutorial for Longan

Longan, also called dragon's eye, is a precious specialty of southern China, rich in nutrients and valued as a precious tonic. The flesh contains 12.38-22.55% sugars, 3.85-10.16% reducing sugars, 9.59-13.59% invert sugars, 0.096-0.109% acid, and vitamin C 43.12-163.70mg/100g of flesh. It also contains vitamin K and inorganic salts. Its medicinal value is high, with effects of tonifying the heart and benefiting the spleen, nourishing the blood and calming the mind, and it can treat weakness after illness, sallow anemia, neurasthenia, blood deficiency after childbirth, and other conditions. Besides being eaten fresh, longan can also be dried and processed into canned goods, longan paste, and more. Its seeds can be used to make wine.

Selecting Good Varieties

Varieties in Fujian include Fuyan, Wuqiuben, Jiaoyan, Chike, Wulongling, Youtanben, Pumingyan, Dongbi, Jidan Longan, Honghezi, and others. Varieties in Guangdong, Guangxi, Sichuan, and other places include Shixia, Wuyuan, Caopuzhong, Zaohe, Daguangyan, Guangyan, Niukouzi, Luyuanqiang, Luyuan No. 6, Luyuan No. 106, Bayuexian, Fuling Huangke Longan, and others.

Raising Seedlings

1. Seedlings: Choose a hillside plot sheltered from wind and protected from frost, with good drainage and irrigation, deep soil, and a loose, fertile texture as the seedling nursery. Plow to a depth of 20-33cm, apply 5000kg of turf soil, then plow and harrow while applying 2000-2500kg of barnyard manure, and then build beds with a height of 20—25cm, a width of 1m, and a ditch depth of 33-40cm. The ratio of the longan nursery to the transplant nursery should preferably be 1:6 or 1:7. Longan seeds must be sown immediately after collection. The extracted seeds should immediately be mixed with sand at a ratio of 1:2-3 and piled to germinate. The best germination temperature is 25°C, and the fine sand should have a moisture content of about 5%. When the embryo bud extends 0.5-1cm, they can be sown in the seedbed. Broadcast sowing can be used, with a seed spacing of 8×10cm, and a sowing rate of 115—250kg per mu. After sowing, cover with 2500-3000kg of burnt soil or sand, then cover with rice straw, and then lead in water for irrigation; drain immediately after it becomes wet. After emergence, management must be strengthened, such as watering and removing the rice straw. Fertilize to ensure vigorous growth of the seedlings. Transplant during the spring rainy season. When transplanting, prepare the land well and apply fertilizer well, with a plant and row spacing of 20×30-33cm, planting 7000-8000 plants per mu. Manage promptly after transplanting.

2. Graft propagation: Use 5-6-year-old seedlings after field planting as rootstock, and graft by the inlay method. Select 2-year-old strong branches as scions, 1cm thick, and those 4—12cm long can also use the approach grafting method. The best time is March to April, and tongue grafting and bud patch grafting can also be used for graft propagation.

3. Air layering propagation: The method is to select, on robust plants more than 15 years old, branches 3-4 years old, 3cm in diameter, with 2—3 branches. Carry out girdling 10-20cm from the branch, about 40-50cm wide, scrape off the cortex, and when tumor-like growth appears after 10-20 days, wrap with grass and mud, hang a pot and fill with soil, or wrap filler with plastic film as the rooting medium.

4. Cuttage: Take young longan shoots of the current year, cut them into 15-17cm stem segments, and insert them into a hotbed at 27—29°C, shading and watering regularly. Before cuttage, first girdle the base of the selected branch, and after 1—2 days, apply 300g of a mixed coating of 100 parts rice straw ash, 10 parts red mud, and 0.18 parts table salt, then wrap it, and after 2 and a half months, cut it from the mother branch and insert it as a cutting.

Planting

Spring planting can be done in February to March, and winter planting can be done in late October. For planting density, a row spacing of 16m and a plant spacing of 4.5m can be used, planting 19-20 trees per mu. Before planting, first dig a planting hole 1m deep and wide, apply river mud at the bottom, then field soil and burnt soil, and above that apply decomposed compost, superphosphate, and plant ash, all of which should be mixed with topsoil. After planting, sufficient irrigation must be given first, then cover with fine soil after irrigation, and thereafter irrigate 1-2 times daily. The planting depth should be such that the root crown is level with the ground surface.

Shaping and Pruning

Use natural open-center shaping. In the 2nd-3rd year after planting, set the trunk at 1.2-1.3m above the ground, cultivate 5-7 main branches within 3-4 years, and finally remove the central leader. Prune 3 times each year. The first pruning is at the flower spike stage, mainly removing diseased spikes, shaded branches, and obstructing branches. The second is during fruit harvest, mainly removing short fruiting branches, water sprouts, diseased branches, dead branches, and shaded branches. The third is in winter, mainly removing shaded branches, dead branches, and diseased branches.

Fertilizing

Apply base fertilizer once each year and topdress 3-4 times. The first topdressing is in February to March, applying night soil and ammonium sulfate, and so on. The second topdressing is at the young fruit stage after flowers fade, about April to May, mainly applying nitrogen fertilizer, with appropriate phosphorus and potassium fertilizer. The third topdressing is from late June to early July, mainly phosphorus and potassium fertilizer, followed by nitrogen fertilizer. The fourth topdressing is when the fruit is close to maturity, still mainly nitrogen fertilizer. The fertilizing method is to open a ditch 30cm from the tree trunk and apply it in. Fertilizing can be combined with intertillage, weeding, earthing up, and drainage and irrigation.

Pest and Disease Control

Pests include litchi stink bug, tea-colored scarab beetle, small gray butterfly, tussock moth, longhorn beetle, longan trunk borer, rear yellow leaf roller, and longan bagworm. Diseases include witches' broom disease, lichen, and rubber disease, and attention should be paid to their control.

Harvesting

Longan is mostly used for processing, so the fruit must be harvested when fully mature. When harvesting, the pruning method should be used. For those used for fresh eating, harvest in the morning or evening.