What varieties of orange trees are there?
Citrus is a tropical and subtropical evergreen fruit tree (except Fructus Aurantii), and there are three genera of Fructus Aurantii, Citrus and Kumquat used for economic cultivation. Citrus grown in China and other countries in the world is mainly citrus.
I. Distribution area
China is one of the important origins of citrus, with rich citrus resources and excellent varieties, and its cultivation history is over 4,000 years. According to textual research, it was not until A.D. 147 1 year that oranges, tangerines and other citrus fruit trees were introduced from China to Lisbon, Portugal, and in A.D. 1665 to Florida, USA.
Citrus in the world is mainly distributed in the area south of 35 north latitude, which is warm and humid, and the area with warmer water body can be pushed northward to 45 north latitude. Citrus is produced in 135 countries in the world, with an annual output of102822 million tons and an area of 1073 million mu, ranking first among the hundred fruits. Brazil's output is the first 124,252,600 tons, followed by the United States,16,335,200 tons, and China is the third.
Citrus in China is distributed between north latitude 16 ~ 37, with the highest elevation of 2,600 meters (Batang, Sichuan), starting from Sanya, Hainan Province in the south, reaching Shaanxi, Gansu and Henan in the north, Taiwan Province Province in the east and Yarlung Zangbo River Valley in Tibet in the west. However, the economic planting areas of citrus in China are mainly concentrated between 20 ~ 33 north latitude and below 700 ~ 1000 meters above sea level. There are 19 provinces (municipalities and autonomous regions) producing citrus in China, including Taiwan Province province. Citrus is mainly produced in Zhejiang, Fujian, Hunan, Sichuan, Guangxi, Hubei, Guangdong, Jiangxi, Chongqing and Taiwan Province provinces 10 provinces (cities, districts), followed by Shanghai, Guizhou, Yunnan and Jiangsu provinces (cities), and also cultivated in Shaanxi, Henan, Hainan, Anhui and Gansu provinces. Citrus is grown in 985 counties (cities, districts) in China.
Second, the significance of cultivation
Citrus fruits are rich in nutrition and good in color, smell and taste. It can be eaten fresh or processed into various processed products, mainly fruit juice. Citrus production ranks first among 100 fruits, and citrus juice accounts for 3/4 of juice, which is widely favored by consumers. According to the analysis of the Central Institute of Health, the edible part of citrus contains 0.05mg of riboflavin, 0.3mg of nicotinic acid, 0.6 mg of ascorbic acid (vitamin C), 0.9g of protein, 0. 1g of fat, 0/2g of sugar 12g of crude fiber and 0.2g of inorganic salt. The content of carotene (provitamin A) in citrus is second only to apricot and higher than other fruits. Citrus also contains a variety of vitamins, in addition, it also contains elements such as magnesium, sulfur, sodium, chlorine and silicon.
Citrus has long life, high and stable yield and high economic benefits. It is the most important fruit tree species in southern China and plays an important role in poverty alleviation and rural economic development.
Third, cultivate characteristics
Citrus fruit trees are mycorrhizal plants and generally have no root hairs. Mycorrhiza and citrus trees coexist, absorbing nutrients from the trees, helping the trees to absorb water, nutrition and secrete hormones and enzymes, and promoting the life activities of citrus trees.
Citrus buds are naked buds with no scales and only bracts. Because the growth of new shoots has the habit of "self-cutting", there is no terminal bud, only lateral buds. Citrus buds are compound buds. Buds planted in leaf axils are called axillary buds, and 2 ~ 4 buds can be planted in one leaf axil. Citrus can germinate many times a year, and the buds are divided into leaf buds and flower buds.
The flowers of citrus are mixed flowers, which have branches, leaves and flowers after germination. Flowers are divided into single flowers and inflorescences: red orange and satsuma mandarin, sweet orange, lemon and grapefruit have inflorescences besides single flowers, and pomelo is mainly inflorescence. Citrus usually needs pollination and fertilization to bear fruit, but mandarin oranges and navel oranges can bear fruit without fertilization. This is parthenocarpy, also called parthenocarpy.
The period of fruit growth and development, from the time when the ovary expands after flowering to the time when the fruit grows completely, is called the fruit growth and development period. There were two physiological fruit drops in this period: the first physiological fruit drop with fruit stalk; What falls from the honey tray is called the second physiological fruit drop. The fruit drop from the second physiological fruit drop to the fruit drop before harvest is called fruit drop before harvest.
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.
There are many propagation methods of citrus seedlings, such as seedling raising, layering, cutting and grafting. At present, grafting is still the best and most common method. Citrus grafted seedlings are composed of scions and rootstocks. The commonly used rootstocks are citrus grandis, lime, red orange, citron, Zhu Luan, orange, jujube and pomelo. ① Fructus Aurantii is used as the main rootstock of sweet orange and mandarin orange. Cold resistance, drought resistance, barren resistance, rotten feet, gummosis, nematodes, dwarfing crown, early fruiting, high and stable yield and improved quality. Orange rootstock is not resistant to spalling, humidity and salinity. (2) Red orange, which is used as the rootstock of oranges and sweet oranges, has developed root system and stands upright after grafting. The fruit is 2-3 years later than the stock of trifoliate orange, but it enters the full fruit stage, with high yield and anti-cracking. (3) Lime, with waterlogging resistance, wind resistance, developed root system and resistance to root rot, is an excellent rootstock for banana oranges and ponkan in southern subtropical areas such as Guangdong and Guangxi.
Citrus diseases include foot rot, gummosis, resin disease, scab, anthracnose, scab, macular disease, powdery mildew, soot disease, damping-off disease and so on. Bacterial disease of ulcer; Root nematodiasis and root-knot nematodiasis; Physiological diseases such as oil spot disease, fruit cracking disease and sunburn; Viruses, viroids and diseases of unknown etiology, such as Huanglongbing, peeling, decline, satsuma atrophy, bacterial wilt, citrus yellowing, etc. There are more than 350 known species of pests such as insects and mites, mainly including mites, scale insects, whiteflies, aphids, longicorn beetles, leaf miners, fruit sucking moths, fruit flies and gall midges.
Four. Harvest, processing and sales
Different uses have different harvest times. Generally speaking, fresh fruits can be harvested earlier than processed fruits, foreign fresh fruits can be harvested earlier than local fresh fruits, and stored fruits can be harvested earlier than fresh fruits. As a fresh fruit, it should be cleaned, waxed, graded and packaged after harvest to improve the commercialization of fruit and increase income.
At present, there are more than 1000 kinds of citrus processed products, among which orange juice is the most important, followed by canned orange petals in syrup, candied fruit and fruit wine. In addition, citrus can also extract by-products such as essential oil, pectin, limonin, seed oil and carotenoids, and citrus peel residue can also be made into fermented feed. 35% of the world's citrus production is used for processing. In Brazil and the United States, 70% ~ 75% of citrus juice is processed, and citrus juice accounts for 3/4 of the juice. The annual processing capacity of citrus in China is actually less than 10% of the annual output.
The world's citrus production ranks first among the hundred fruits, with 1998 output 102822 million tons, far exceeding 59 million tons of bananas, 57 million tons of grapes and 56 million tons of apples. Since the mid-1970s, there has been an annual surplus of 3% ~ 5% of citrus in the world. At the end of 1980s, some dwarf varieties in China were unsalable.
China should increase the adjustment of citrus variety structure, develop famous, special and excellent citrus in market demand, change from quantitative type to quality type in the past, and improve the quality and commercialization of fruits.
Respondent: It's sunny today-regional director 1 1 grade 2007-6-3 14:47.
Reporting should be easy.
When buying orange seedlings, the distance between trees must be far. Then there is fertilization, as well as insects and pesticides. Anyway, orange trees are good to grow. My family has an orange grove, but eating it at home is definitely unprofessional. If you want to major, you should buy books about agricultural magazines.
I hope it helps you!