Longan Cultivation Technical Tutorial: Detailed Explanation of the Latest Growing Methods
Longan is also called guiyuan; it is a precious specialty of southern China, rich in nutrients and valued as a rare 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% acids, and vitamin C 43.12-163.70 mg per 100 g of flesh. It also contains vitamin K and inorganic salts. It has high medicinal value, with the effects of tonifying the heart and benefiting the spleen, nourishing the blood and calming the mind, and can treat conditions such as weakness after illness, sallow anemia, neurasthenia, and blood deficiency after childbirth. Besides being eaten fresh, longan can also be dried and processed into cans, 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.
Longan Propagation
1. Seedling plants
Choose a hillside slope sheltered from wind and frost, with good drainage and irrigation, deep soil, and a loose, fertile texture as the nursery site. Plow 20-33 cm deep, apply 5000 kg of turf soil, then plow and harrow and apply 2000-2500 kg of barnyard manure, then build beds 20-25 cm high and 1 m wide, with furrows 33-40 cm deep. The ratio of longan seedling nursery to transplant nursery should be 1:6 or 1:7. Longan seeds must be sown as soon as they are collected. 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 has elongated 0.5-1 cm, they can be sown in the seedbed. Broadcasting is possible, with a seed spacing of 8×10 cm, and a sowing rate of 115-250 kg per mu; after sowing, cover with 2500-3000 kg of burnt soil or sand, place rice straw on top, then lead in water for irrigation and drain immediately after wetting. After emergence, management must be strengthened, such as watering and removing the rice straw. Fertilize to ensure healthy seedling growth. Transplant during the spring plum rains. When transplanting, prepare the land well and apply fertilizer well, with a plant and row spacing of 20×30-33 cm, planting 7000-8000 plants per mu. Manage promptly after transplanting.
2. Grafting propagation
Use seedling plants that have been in the field for 5-6 years as rootstock, and graft by the side-veneer grafting method. Select 2-year-old strong branches as scions, 1 cm thick and 4-12 cm long; the approach grafting method can also be used, with March to April being the best time; tongue grafting and chip budding can also be used for grafting propagation.
3. Air layering propagation
The method is to select, on strong plants more than 15 years old, 3-4-year-old branches with a diameter of 3 cm and 2-3 side branches. At 10-20 cm from the branch, perform girdling about 40-50 cm wide, scrape off the bark, and when tumor-like growth appears after 10-20 days, wrap with grass and mud, hang a pot and fill with soil, or wrap the filling material with plastic film as the rooting medium.
4. Cuttings
Take young longan shoots of the current year, cut them into 15-17 cm stem sections, and insert them into a hotbed at 27-29°C, shading and watering regularly. Before cutting, first girdle the base of the selected branch, and after 1-2 days, apply 300 g of a mixed coating of 100 parts rice straw ash, 10 parts red mud, and 0.18 parts table salt, then wrap it; after 2 and a half months, cut it away from the mother branch and insert it as a cutting.
Longan Planting Techniques
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 16 m and a plant spacing of 4.5 m can be used, planting 19-20 trees per mu. Before planting, first dig a planting hole 1 m deep and wide, apply river mud below, and field soil and burnt soil above, then apply decomposed compost, superphosphate, and plant ash, all of which should be mixed with the topsoil. After planting, the plants must first be thoroughly irrigated, then covered with fine soil after irrigation, and thereafter irrigated 1-2 times daily. As for planting depth, the root crown should be level with the ground.