(1) Longan seedlings selected in the nursery are not tolerant to low temperature, and their roots are brittle and easy to break, and their ability to regenerate new roots after root cutting is weak. Miao Di should choose low temperature and cold damage in winter, especially to avoid the low-lying land where cold air is easy to deposit in winter or the north slope with strong wind in winter, and it is better to use loose and fertile sandy soil. If there is too much sand, the heat transfer is fast, and the soil temperature is too high in summer, which is unfavorable for the growth of seedlings, and it is difficult for roots to carry soil when seedlings leave the nursery, which affects the survival of planting. Too sticky soil has poor air permeability and is easy to accumulate water in rainy season. When the weather is dry, soil hardening affects the growth of seedlings. As long as the newly reclaimed red soil slope is fully ploughed and matured, and sufficient organic fertilizer is applied as base fertilizer, the seedlings with irrigation conditions will grow well.
The nursery should be plowed and raked in advance, with a depth of 20-30 cm, and about 5000 kg of decomposed manure, fire-poured soil and other miscellaneous fertilizers should be sprinkled every 667 m2 as base fertilizer, then plowed and raked flat, and then ditched and leveled, with a height of 20-25 cm and a width of1m. The ratio of longan seedbed to transplanted nursery depends on the sowing amount and the row spacing of transplanted plants, and generally the transplanted nursery should be close to 660. Longan seedlings need a large amount of fertilizer, which can be rotated with vegetables or green manure to improve soil fertility, and can also be rotated with other fruit seedlings. (2) Seeding longan seeds is generally sowing with harvest. Around the Millennium, the temperature is suitable for rapid germination, which is the most ideal. For canned seeds, immediately wash them with sand, remove the pulp attached to the umbilical cord, rinse and screen them to remove defects. Use the mixed sand of 1: 2 or 1: 3 to accelerate germination, keep the water content of fine sand at about 5%, and the optimum germination temperature is 25℃. The germination rate decreased above 30℃, and the germination ability was lost above 33℃. When mixed sand is used to accelerate germination, the germination rate can reach 95%, and it can only reach 60% ~ 75% without accelerating germination, but it should be accelerated. If the seeds are not sown immediately, the sand with water content of 1% ~ 2% can be mixed and stored in the shade, but it can only be stored for 15 ~ 20 days at most.
After 2 ~ 3 days of accelerating germination, when the germ is extended by 0.5 ~ 1 cm, it can be sown in the seedbed. If the bud is too long, it is easy to break and the stem of the seedling is bent, which affects the quality of the seedling.
Longan is generally sown, with the grain spacing of 8 ~ 10 cm, and the sowing amount per 667㎡ is10 ~125 kg, and the small seeds can be reduced to 100 kg. Seeds that accelerate germination should be sown in the morning and evening. Gently press the seeds into the soil with a thick round wooden stick or flat plate to make them closely contact with the soil to absorb water, then cover them with a layer of straw for irrigation in the furrow, and drain them after the soil is soaked. Similarly, the row spacing is 12 ~ 15cm, and the sowing amount is 30 ~ 35 kg per 667 m2. Interplanting barley and wheat between rows of drilling can provide shade and antifreeze protection for longan seedlings. (3) Seedling management: when the seedlings grow to 30%, remove half of the covered straw, and when the seedlings grow to 80%, remove them all. Then cover the unexposed seeds with soil and water to keep them moist. When the seedlings grow to the first mature leaf (two leaflets are primary cotyledons), human manure diluted with water can be applied twice a month, and soil miscellaneous fertilizer can be applied to 1: 12, so as to facilitate overwintering, stop water and fertilizer application and prevent freezing injury of winter shoots. Excessive fertilizer concentration will cause fertilizer damage and scorch the tips of young leaves. /kloc-Fertilize once from late October to early February of next year (65438+) to promote the germination of spring shoots, and transplant them after maturity (April).
The taproot of longan seedlings is developed, and the growth of lateral roots is inhibited. When the real leaves grow to 4 pieces, you can insert a flat-headed sharp knife at a 45-degree angle 3.5 ~ 5.0 cm away from the trunk of the seedling, then cut off the main roots of the seedling, and then strengthen irrigation and moisturizing. After about 1 month, 3 ~ 4 lateral roots can be produced in the cut-off part of the main root (Figure L). After the taproot was cut off, the seedlings were temporarily inhibited but quickly recovered, and the final growth was better than that without root cutting, which improved the survival rate of transplanting.
Figure 1 During the low temperature period of longan seedlings in winter, it is best to cover the seedbed with plastic film to increase the temperature of the seedbed, prevent the occurrence of freezing injury, strive for more suitable growth time for the seedlings and shorten the seedling raising period. When the sun is strong, attention should be paid to uncovering the film, ventilation and cooling, so as to avoid rotten buds and burning seedlings. (4) Transplanting and management after transplanting Longan is generally transplanted in the spring of the second year after sowing, which has high survival rate, less labor-saving management and rapid growth recovery. Transplanting usually occurs between the rainy season and the vernal equinox, before the spring seedlings germinate. Although the survival rate of transplanting is high at this time, the growth of spring shoots is poor. Spring bamboo shoots are mostly transplanted between Qingming and Grain Rain, with high temperature and good growth. However, it should be noted that intermittent dry weather affects the survival rate, so transplanting should be carried out sooner or later or on cloudy days. From the production practice of longan transplanting in recent years, it is found that due to long growth time and large seedlings, some branches and leaves often need to be cut off when transplanting in spring. After transplanting, there is a growth stagnation period before the root absorption of seedlings returns to normal, which affects the growth of seedlings. If it is not properly managed, the survival rate will be significantly reduced. According to the experiments of some nursery units, transplanting in advance can have better effect. The key period of early transplanting is 50 days after sowing. Generally, it is best to transplant after the first branch of seedlings matures. At this time, the seedling and seed nucleus are still connected, and the seed coat is shiny and the seed nucleus is rich in nutrition, which can meet the needs of seedling growth and make up for the temporary malabsorption of root system after seedling transplantation. The survival rate of transplantation is high, and it still grows normally after transplantation, and there is basically no stagnation period. But we should pay attention to careful management to prevent frost.
Transplanting nursery is the place where longan seedlings grow for a long time. It is necessary to plow and rake well in advance, apply sufficient organic base fertilizer (5000 kg of decomposed manure can be applied every 667 m2), and then plow and rake again to level the ridge.
When transplanting, longan seedlings without radicle cutting have few roots except the lateral roots of the main roots, so the survival rate of transplanting is difficult, so it is best to choose cloudy days or evening and plant them while raising seedlings. After seedling raising, the seedlings are graded according to their size, the excessively long taproots and branches and leaves are appropriately pruned, and transplanted separately according to their grades. The row spacing of transplanted plants is generally 1.5 ~ 20 cm, and there are two kinds of1.1.0000 ~1.20 thousand plants every 667 meters. Spray root water after planting.
At the initial stage of transplantation, pay attention to keep the soil moist to ensure survival. After transplanting, the new buds germinate for the first time, that is, fertilization begins, and then fertilization is applied every time the new buds mature. The lateral buds germinated above 0/5 cm of seedling trunk/kloc-should be smoothed in time, and concentrated nutrients should be used to thicken the seedling trunk and make the seedling trunk straight, which is beneficial to grafting. When the diameter of the stem reaches more than 0.8 cm, grafting can be carried out. Before grafting 1 month, it is best to apply fertilizer 1 time to promote seedling growth and improve grafting survival rate.