(1) temperature:
Temperature is an important factor affecting the growth, flowering, fruiting and geographical distribution of longan. When the average temperature reached above 20℃, it was more suitable for the growth of longan. This area can form a good economic planting area. When the temperature drops to 0℃, longan seedlings are vulnerable to freezing injury. When the temperature dropped to ~ 0.5℃ ~ ~ 4℃, longan trees showed different degrees of freezing damage. The degree of freezing injury is related to the geographical environment. Generally speaking, the trees on the hillside are less damaged than those on the flat and lowland; Trees in the south and southwest suffer less than those in the north and northeast; Trees with large water bodies nearby are less affected than trees without large water bodies. In addition, young trees suffer more than adult trees; Strong tree potential, dense crown, light damage and quick recovery after damage.
In early spring, longan needs a low temperature of 8- 14℃ for a period of time to facilitate flower bud differentiation. Beyond this temperature range, the higher the temperature and the longer the duration, the more likely the longan tree will cause "shoot tip disease". Longan needs a temperature of 18-27℃ when it blooms. At the temperature of 25-32℃, longan grows fast, with high sugar content and good quality.
(2) Moisture:
Longan is drought-tolerant, wet-loving and afraid of waterlogging. During the growth and development of longan in the annual cycle, the demand for water in each growth stage is different. Autumn shoots mature every year 1 1 month until April of the following year. During this period, water demand is low, avoiding pumping in winter shoots and increasing nutrient accumulation in branches and leaves, which is beneficial to flower bud differentiation, spike pumping, flowering and fruit setting. In other periods, especially in July and August, the water demand is more. If water is scarce, it will affect the growth and development of roots and branches, and affect the yield and quality of fruits; If in the late stage of fruit development, long-term drought and showers will also cause fruit cracking and fruit dropping. Longan has mycorrhiza and strong drought tolerance; When the orchard is flooded for a short time, longan will not be affected, but if the orchard is flooded for a long time or the groundwater level is high, the longan root system will decline due to suffocation and root rot.
(3) Soil:
Longan has no strict requirements on soil conditions. It can even grow in barren, dry and acidic hilly red soil. The hilly red soil has deep soil layer, good drainage, air circulation and sufficient sunshine. If the soil can be deeply improved and more organic fertilizers are applied, longan can grow well and have a good harvest. However, to plant longan on sloping land, it is necessary to do a good job of soil and water conservation. The garden should choose the southeast, south and southwest slopes to avoid the wind and cold. Good soil should be deep, soft and moist, rich in organic matter and slightly acidic soil, with a pH value of 5.5-6.5. In addition, longan is a positive fruit tree. Adequate light is beneficial to its growth and fruit, but the fruit should be properly shaded. Longan has a huge crown and is vulnerable to wind damage. Strong winds can also cause a lot of fruit loss. Therefore, we should pay attention to it when planting longan.