Distribution of producing areas of Citrus

Citrus prefers warm and humid climate, and its cold resistance is slightly stronger than that of pomelo, lime and sweet orange. The subfamily Citrus of Rutaceae is distributed between 16 °and 37 °N. China is one of the important places of origin of citrus. Citrus is rich in resources and has been cultivated for more than 4000 years. Let's take a look at the distribution of citrus.

The origin of citrus in China

Chinese citrus is distributed in 16 °~ 37 °N latitude, with the highest elevation of 2600 m (Batang, Sichuan), starting from Sanya City in Hainan Province in the south, Shaanxi, Gansu and Henan in the north, Taiwan Province in the east, and the Yarlung Zangbo River Valley in the west of Xizang. The economic cultivation areas are mainly concentrated in latitude 20 °~ 33 °north, with an elevation of less than 700 to 1000 meters.

Citrus is produced in 19 provinces (municipalities and autonomous regions), including Taiwan Province. Citrus is mainly produced in 10 provinces (cities and regions), including Zhejiang, Fujian, Hunan, Sichuan, Guangxi, Hubei, Guangdong, Jiangxi, Chongqing and Taiwan, followed by Shanghai, Guizhou, Yunnan, Jiangsu and other provinces. Shaanxi, Henan, Hainan, Anhui and Gansu provinces also grow.

There are 985 citrus growing counties (cities and districts) in the country.

The world origin of citrus

The citrus in the world is mainly distributed in the area south of latitude 35 °N. it is warm and humid, and the area with large water body warming can be pushed northward to latitude 45 °. There are 135 countries in the world that produce citrus, with an annual output of 102.822 million tons and an area of 107.3 million mu, ranking first among the 100 fruits.

Citrus production ranked first in Brazil, 24.2526 million tons, followed by the United States, 16.3352 million tons, China third, 10.78 million tons, followed by Mexico, Spain, Iran, India, Italy and other countries.

Producing conditions of citrus

1. Environmental factors: the growth and development, flowering and fruiting of citrus trees are closely related to temperature, sunshine, moisture (humidity), soil, wind, altitude, topography and slope aspect.

2. The influence of low temperature: the producing conditions of citrus have the greatest influence on the temperature, even if the temperature difference of 0.5 ℃ sometimes appears completely different results, citrus growth and development requires a temperature of 12.5-37 ℃, and the day and night temperature of flower bud differentiation in autumn is about 20 ℃ and 10 ℃ respectively. The soil temperature of root growth is roughly the same as that of aboveground parts, and too low temperature will freeze citrus, sweet orange-4 ℃. Satsuma mandarin-5 ℃ will freeze the branches and leaves, sweet orange-5 ℃, Wenzhou mandarin mandarin-6 ℃ will frostbite big branches and branches, sweet orange-6. 5 ℃, Wenzhou mandarin mandarin-9 ℃ will freeze to death.

3. The effect of high temperature: high temperature is not conducive to the growth and development of citrus. When the air temperature and soil temperature are higher than 37 ℃, the fruit and root system stop growing, and the temperature has obvious effect on the quality of the fruit. In a certain temperature range, the sugar content and soluble solids content increase with the increase of temperature, the acid content decreases, and the quality becomes better.

4. light effect: citrus is a tree species with strong shade tolerance, but good sunshine is still needed for high quality and high yield. In general, the areas with annual sunshine hours of 1200 to 2200 hours can grow normally. For example, compared with Chongqing citrus producing areas with good sunshine and rich heat, South China has high sugar content, low acid content and high sugar-acid ratio.

5. Rainfall conditions: tropical and subtropical areas with an annual rainfall of about 1000 mm are suitable for citrus cultivation, but irrigation is often needed because of the uneven distribution of annual rainfall. The relative water content of the soil is 60% to 80%, and less than 60% requires irrigation. Too much Rain Water will cause stagnant water in the soil or citrus orchards with high groundwater level and poor drainage, which will kill the roots. Citrus trees require an air relative humidity of about 75%.

6. Soil conditions: citrus can adapt to a wide range of soil, purple soil, red-yellow soil, beach and beach, pH 4.5-8 can grow, pH 5.5-6.5 is the most suitable. Citrus root growth requires higher oxygen content, with loose soil texture, good structure, organic matter content of 2% to 3%, well-drained soil is the most suitable.