The growth, flowering and fruiting of citrus fruit trees are closely related to environmental conditions such as temperature, sunshine, moisture (humidity), soil, wind, altitude, topography and slope direction, among which temperature has the greatest influence. Even if the temperature difference is 0.5℃, sometimes there will be completely different results. The growth and development of citrus need a temperature of 65438 02.5 ~ 37℃. The day and night temperatures of flower bud differentiation in autumn are about 20℃ and 65438 00℃, respectively, and the soil temperature of root growth is roughly the same as the ground temperature. If the temperature is too low, oranges will be frozen. When the sweet orange is at -4℃ and the satsuma orange is at -5℃, the branches and leaves will be frozen. When the sweet orange is below -5℃ and the satsuma orange is below -6℃, the plants will freeze to death.
High temperature is also not conducive to the growth and development of citrus. When the air temperature and soil temperature are higher than 37℃, fruits and roots stop growing. Temperature also has obvious influence on fruit quality: in a certain temperature range, with the increase of temperature, the sugar content and soluble solids increase, the acid content decreases and the quality becomes better. Citrus is a tree species with strong shade tolerance, but good sunshine is needed for high quality and high yield. Generally, areas with annual sunshine hours 1200 ~ 2200 hours can grow normally. For example, compared with Chongqing citrus producing areas with less sunshine, South China with good sunshine and abundant calories has higher sugar content, lower acid content and higher sugar and acid content. Generally, tropical and subtropical regions with annual rainfall of about 1000mm are suitable for citrus planting, but irrigation is often needed because of uneven distribution of annual rainfall. The suitable relative water content of soil is 60% ~ 80%, and irrigation is needed when it is lower than 60%. Too much rain will cause soil water accumulation or high groundwater level and poor drainage in citrus orchards, resulting in root death. Citrus fruit trees require that the air relative humidity should be around 75%.
Citrus can adapt to a wide range of soils. Purple soil, red and yellow soil, beaches and beaches can all grow at pH 4.5 ~ 8, and pH 5.5 ~ 6.5 is the most suitable. The growth of citrus roots needs high oxygen content, and the soil with loose texture, good structure, organic matter content of 2% ~ 3% and good drainage is the most suitable.
Apple is a temperate fruit tree, which likes cold and dry. It requires that winter is not cold, summer is not cool, and the annual variation is small and the daily variation is large. The suitable temperature range is the annual average temperature of 9- 14℃, the extreme minimum temperature in winter is not lower than-12℃, the highest monthly average temperature in summer is not higher than 20℃, the annual accumulated temperature is about 5000℃ ≥ 10℃, and the average temperature in the growing season (April-10) is 60. Low temperature time is not enough, leaves and flowers are delayed irregularly, and some flower buds don't even germinate. In May, the scales became loose and fell off, which became a dead pile and seriously reduced production. When the absolute low temperature is lower than -30-32℃, freezing injury occurs again.
Apples are not strict about the soil. Clay, sandy soil and loam can be used, but sandy loam with deep soil layer and loose and fertile soil is the best. Thick soil with shallow soil layer and many gravels must be improved before planting.