An Overview of the Latest Distribution of Citrus Producing Areas
Citrus prefers a warm and humid climate, and its cold tolerance is slightly stronger than that of pomelo, bitter orange, and sweet orange. The Rutaceae subfamily Aurantioideae is distributed between 16° and 37° north latitude. China is one of the important places of origin for citrus, with abundant citrus resources and numerous excellent varieties, and a cultivation history of more than 4000 years. Now let us take a look at the distribution of citrus producing areas!
Citrus Producing Areas in China
Citrus in China is distributed between 16° and 37° north latitude, with the highest altitude reaching 2600 m (Batang, Sichuan), from Sanya City in Hainan Province in the south, to Shaanxi, Gansu, and Henan in the north, from Taiwan, China in the east, to the Yarlung Zangbo River valley in Tibet in the west. The commercial cultivation areas are mainly concentrated between 20° and 33° north latitude, below an altitude of 700 to 1000 m.
Nationwide, 19 provinces (municipalities and autonomous regions), including Taiwan, China, produce citrus. Among them, the 10 major citrus-producing provinces (municipalities and regions) are Zhejiang, Fujian, Hunan, Sichuan, Guangxi, Hubei, Guangdong, Jiangxi, Chongqing, and Taiwan, China, followed by Shanghai, Guizhou, Yunnan, Jiangsu, and other provinces (municipalities). Shaanxi, Henan, Hainan, Anhui, and Gansu also have plantings.
There are 985 counties (cities and districts) nationwide that grow citrus.
Citrus Producing Areas in the World
World citrus is mainly distributed in areas south of 35° north latitude. It prefers warmth and humidity, and in regions with large water bodies that raise temperatures, it can advance northward to 45° north latitude. There are 135 countries in the world that produce citrus, with an annual output of 102.822 million tons and an area of 10.73 million mu, both ranking first among all fruits.
Brazil ranks first in citrus production with 24.2526 million tons, the United States ranks second with 16.3352 million tons, China ranks third with 10.78 million tons, followed by Mexico, Spain, Iran, India, Italy, and other countries.
Conditions of Citrus Producing Areas
1. Environmental factors: The growth, development, flowering, and fruiting of citrus trees are closely related to environmental conditions such as temperature, sunlight, water (humidity), soil, as well as wind, altitude, topography, and slope aspect.
2. Low-temperature effects: Among the conditions of citrus producing areas, temperature has the greatest impact. Even a temperature difference of 0.5°C can sometimes produce completely different results. Citrus growth and development require a temperature of 12.5 to 37°C. In autumn, flower bud differentiation requires day and night temperatures of about 20°C and about 10°C respectively. The soil temperature for root growth is roughly the same as that above ground. Excessively low temperatures will freeze citrus. Sweet orange at -4°C and Satsuma mandarin at -5°C will cause branches and leaves to freeze. Sweet orange below -5°C and Satsuma mandarin below -6°C will freeze large branches and trunks. Sweet orange below -6.5°C and Satsuma mandarin below -9°C will freeze the plants to death.
3. High-temperature effects: High temperatures are also unfavorable to the growth and development of citrus. When air temperature and soil temperature are above 37°C, fruit and root growth stop. Temperature also has an obvious effect on fruit quality. Within a certain temperature range, as temperature increases, sugar content and soluble solids usually increase, acid content decreases, and quality improves.
4. Light effects: Citrus is a tree species with relatively strong shade tolerance, but good sunlight is still needed for high quality and high yield. Generally, areas with an annual sunshine duration of 1200 to 2200 hours can all support normal growth. For example, compared with the Chongqing citrus producing area, which has less sunshine, South China, which has good sunshine and abundant heat, produces fruit with higher sugar content, lower acid content, and a higher sugar-acid ratio.
5. Rainfall conditions: Generally, tropical and subtropical regions with annual rainfall of about 1000 mm are suitable for citrus cultivation, but due to uneven distribution of annual rainfall, irrigation is often needed. The suitable relative soil moisture content is 60% to 80%. Below 60%, irrigation is needed. Excessive rain, causing soil waterlogging or a high groundwater table, in citrus orchards with poor drainage will cause root death. Citrus trees require an air relative humidity of about 75% as suitable.
6. Soil conditions: Citrus has a wide range of adaptability to soil. It can grow in purple soil, red-yellow soil, sandy beach, and coastal mudflat with a pH value of 4.5 to 8, and a pH value of 5.5 to 6.5 is most suitable. Citrus root growth requires a relatively high oxygen content, and soil with loose texture, good structure, organic matter content of 2% to 3%, and good drainage is most suitable.