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The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

author:Farmers and farmers
The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

In recent years, the mainland citrus industry has developed rapidly, ranking first in the world in terms of planting area and output. However, compared with the United States and other major citrus-producing countries, there is still a big gap, which has a certain relationship with the handling of some problems in the process of development. Macroscopically, it refers to the industrial structure and development direction; Microscopically, it is a variety of choices made by the majority of growers when they actually operate.

Professor Shen Zhaomin, former director of the Citrus Research Institute of the Chinese Academy of Agricultural Sciences, briefly described the relevant parties of the six major choices, including variety selection, seedling selection, planting selection, fertilizer water selection, mode selection and post-production selection.

Variety selection

The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

Old varieties and excellent new varieties

Varieties are the basis of citrus production, good varieties can be high-quality, abundant, stable yield, varieties are not good, either delay in fruit, or low yield and inferior quality, seriously affecting production efficiency.

In the selection of planting varieties, we should adopt the attitude of "liking the new and not getting tired of the old". That is, new varieties with high quality and abundant yield should be actively planted, but before planting, it is necessary to understand whether the variety is suitable for local cultivation, it is best to carry out a small number of high-quality replacement seeds to observe whether it is high-quality and abundant, and then choose to expand or scale planting to replace the original old varieties that dwarf.

However, old varieties can be planted for a long time, and they must have their advantages in adaptability, yield or easy planting and management, and they cannot like new varieties and dislike old varieties. In particular, the current introduction of new varieties is not standardized enough, and some have been promoted without comparative tests and regional tests; What's more, individual seedling breeders have indiscriminately crowned new varieties with new names, falsely advertised, and launched their "new varieties" to make money, causing growers who do not know the truth to suffer a lot. Therefore, we should like excellent new varieties, but we should also be cautious about replacing old varieties planted.

Large varieties versus small varieties

In China, the bulk varieties of citrus mainly refer to varieties of sweet oranges, broad-skinned citrus and pomelo; Small varieties refer to lemons and kumquats, among others. There are many large varieties cultivated, especially the navel orange varieties such as Newhall navel orange in the sweet orange category, Wenzhou honey mandarin, Ponkan and sugar orange in the broad-skinned citrus, Shatin pomelo and Guanxi honey pomelo in the pomelo, etc., with a large cultivation area and more output.

Small varieties refer to varieties with relatively small cultivation area and yield. However, large varieties and small varieties are also variable, and small varieties can become bulk varieties with the increase of cultivation area and yield. To this end, growers should understand the changes of bulk varieties and small varieties of citrus and the supply and demand of the market, so as to facilitate the accurate selection of varieties with good market prospects and good economic benefits.

Domestic varieties and imported varieties

The mainland is a big country of citrus varieties, known as the "world's treasure house of citrus resources", with more than 100 cultivars and dozens of main cultivars, which can be said to have everything. Historically, the mainland has always been one of the important origins of citrus, making significant contributions to the development of the world citrus industry, and at the same time, many excellent and new varieties have been introduced from the world's citrus-producing countries at different times, which have played a great role in production.

For example, the orange, which originated in Tiantai, Zhejiang, on the mainland, was brought back to Japan by Japanese monks on their way back from incense on Tiantai Mountain, and later mutated into a seedless Wenzhou mandarin. Later, the mainland introduced it from Japan, especially the extra early, early, and medium-to-late ripening Wenzhou mandarin; Newhall navel oranges, voltingsummer oranges, etc., imported from the United States, have been cultivated in large quantities on the mainland. However, the promotion of introduced varieties should pay special attention to adaptability, regionalism and rootstock testing, so as not to cause large losses due to discomfort.

Seedling selection

The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

Dwarf rootstock vs. Joe rootstock

Citrus cultivation basically uses grafted seedlings. Therefore, the strength of its growth, the height of the tree, the early or late fruiting, the level of yield, the quality and resistance to adversity, diseases and pests are all affected by the rootstock.

At present, the rootstocks used in the world's main citrus-producing countries are mainly divided into jogical anvils and dwarf anvils. The United States, Brazil, Italy, Spain, South Africa, Australia and other countries mainly use Joe anvils; China, Japan, South Korea and other countries mainly use dwarf anvils. Qiaohua anvil is represented by Troia and Carrizzo of citrus orange, and is mainly used as a rootstock for sweet oranges; The dwarf rootstock, represented by Citrus dwarf, is mainly used as a rootstock for broad-skinned citrus, especially Wenzhou mandarin.

The citrus trees using the Johua anvil are tall and slightly later than the dwarf anvil, but the late yield and single plant yield are high, and the planting density should be thin, which is suitable for mechanized orchards. The dwarf anvil has a short crown, bears fruit early, and is suitable for dense planting.

Citrus rootstock should have good affinity after grafting with varieties, and the affinity of the same rootstock for different varieties may be different. For example, Carrizo citrus orange is used in the introduction of Newhall navel orange, voltingsummer orange, Hamlin and other varieties after the tree growth is vigorous, the results are normal, but it is used as the rootstock of Yujin orange selected from the domestic jin orange, soon after planting, the young tree has the problem of thick branches, yellowing of leaves, weak growth and dead trees.

Open field seedlings versus container seedlings

The open-field seedlings of citrus are traditional and conventional open-field seedlings, also known as non-container seedlings; Container seedlings are seedlings cultivated in containers, usually rootstock seedlings are carried out in modern facilities (greenhouses, greenhouses), and after grafting, container seedlings are moved to open fields for cultivation.

Container seedlings are usually robust seedlings free of viruses (schizophrea and leaf crushing disease). Generally, the root system is developed, the seedlings are robust, without viruses, they can be planted all year round, and there is no slow seedling period after planting, the survival rate is almost 100%, and the seedlings without viruses also have the advantages of long harvest period and abundant yield.

The United States, Spain, Brazil and other countries that mainly produce citrus in the world have widely used container seedlings in the 60s and 70s of the 20th century. Since the mid-90s of the 20th century, the mainland has carried out experimental promotion in Chongqing, and now Fujian, Jiangxi, Hunan, Hubei, Guangdong, Guangxi, Sichuan, Zhejiang and Yunnan provinces and regions are also vigorously promoting it.

The initial investment of container seedlings is large, such as the cost of long-distance transportation is higher. In the future, it is advisable to use seedlings with a moderate scale and control of transportation distances to facilitate popularization. The vigorous popularization of virus-free container seedlings is conducive to the sustainable and healthy development of the mainland citrus industry.

Planting options

The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

Pay attention to new planting and transformation of old trees

The mainland citrus industry has developed rapidly, and the most intuitive embodiment is the rapid expansion of the newly planted citrus area. With the continuous expansion of planting area and the increase of citrus tree age, the aging citrus tree continues to increase. According to recent incomplete statistics, old citrus trees account for about 35% of the country's citrus area.

In addition, at present, the area of citrus in the mainland has ranked first in the world for a long time, and the actual cultivation area has repeatedly exceeded the planned and development plan area, which should not be expanded indefinitely. The existing citrus old trees have low yields due to problems such as closed crowns or soil compaction and barrenness, but most of the trees are still healthy and can continue to yield after transformation, and the investment in transformation is far lower than the investment in new gardens, and it can achieve results relatively quickly.

Dense cultivation and rare cultivation

The planting density of citrus is related to rootstocks, varieties, terrain, cultivation management level, whether planned dense planting is implemented, etc., and even related to different countries and even different periods.

Generally, those who use dwarf anvils are denser than those who use qiaohua anvils, and the mountain lands are denser on flat ground, and the varieties are vigorous and the tall trees are planted more rarely, such as pomelo and grapefruit; Kumquat with short tree body and especially early maturing Wenzhou mandarin mandarin are densely planted. If the canopy management level is high, if the canopy size can be effectively controlled, the planting is dense, the management level is low, and the canopy growth is thinner. The density of planned dense cultivation is double, or even doubled, than that of conventional cultivation.

Therefore, the planting density of citrus-producing countries in the world is also different, such as the United States, Brazil, Italy and Australia and other countries, because citrus mostly use qiaohua anvil, orchard mechanization degree is higher, planting density is thinner, the general sweet orange plant row spacing is 5 meters×6 meters (22 ~ 23 plants per acre), or even 6 meters × 6 meters (18 ~ 19 plants per acre).

China, Japan and South Korea and other citrus planting density is large, the anvil Wenzhou mandarin plant row spacing is generally 3 meters×4 meters, or even 3 meters×3 meters, that is, 56 and 74 plants per mu respectively. In the 70s and 80s of the 20th century, the planned dense planting was implemented in China, and the density of planting was relatively large, and since the end of the 20th century, the density has changed from dense to moderate dense planting.

Pre-planting and post-planting soil modification

The vast majority of mainland citrus orchards need to be thickened by the soil layer and fertilized by the soil before they can be planted (except for a few mature lands that use the deep and fertile soil layer). Where the citrus planting land needs to be resoiled, it is recommended to complete the soil conversion before planting seedlings. Sometimes if it is too late to change the soil and fertilize before planting, the soil improvement should be completed within 3 years after planting of citrus seedlings to facilitate the normal growth of citrus plants and put into production as scheduled.

Fertilizer water selection

The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

Organic fertilizer vs. chemical fertilizer

Both organic and chemical fertilizers are required in citrus production.

The role of organic fertilizer:

First, the nutritional effect. Organic fertilizer is rich in various nutrients needed for citrus growth, and can continuously supply the growth and fruiting needs. Organic matter decomposes in the soil to produce carbon dioxide, which can be used as a raw material for photosynthesis and is conducive to increasing production. The supply of nutrients is the main role of organic fertilizer.

The second is to improve the soil. Organic fertilizer can increase soil organic matter content, update soil humus composition, improve soil physical properties, increase soil fertilizer retention and water retention capacity, and fertilize soil. Soil organic matter is an important indicator of soil fertility and the material basis for forming the soil environment, which is composed of undecomposed and semi-decomposed organic matter residues and humus in the soil. Organic fertilizer can form agglomerates, plus its density is generally smaller than soil, the application of soil organic fertilizer can reduce soil bulk density, improve soil aeration, easy to absorb heat and moisture.

The role of fertilizers:

First, the composition is single and the content is high. Contains one or more nutrients necessary for the growth and development of citrus. If properly applied, the effect of increasing production is obvious.

Second, it is easy to absorb for citrus. Most of them are water-soluble or weakly acid-soluble compounds, which are fast-acting to fruit trees and can be directly absorbed by roots or leaves.

The shortage of labor, the management of citrus fruit tree production, especially in the management of fertilizer, is more prominent, mainly manifested in: neglect of the application of organic fertilizer and soil improvement fertilizer.

Compared with before the 90s of the 20th century, the application of organic fertilizer in citrus orchards has been greatly reduced, and young orchards have used the gap between rows to plant green manure less and less, resulting in a serious lack of organic matter in citrus soil, and the organic matter content in some production areas is below 0.5%, which is far from meeting the demand for organic matter for the normal growth results of citrus plants.

From the perspective of the sustainable development of citrus production and increasing the planting efficiency of fruit farmers, we must pay attention to the use of organic fertilizer.

Routine fertilization versus formula fertilization

Conventional fertilization refers to the traditional fertilization according to the different seasons of citrus, which often leads to insufficient or excessive nutrition of plants.

Formula fertilization refers to the determination of various nutrients of the soil available to fruit trees, combined with the demand for various nutrients at each stage of growth and development of fruit trees, based on this, proportional to various required fertilizers, and according to the percentage of fertilizers can be absorbed and utilized in the soil, to determine the amount of fertilizer. The soil testing formula fertilization technology of fruit trees can achieve the purpose of saving fertilizer and increasing yield, losing weight and improving quality, efficient fertilizer distribution, soil cultivation and soil transformation and ecological protection.

For formula fertilization, fruit farmers can ask the local agricultural technology extension station and soil fertilizer station to measure the nutrient elements and their content in the soil of the orchard, and propose a formula fertilization plan according to the nutritional needs of citrus at each growth stage.

Conventional irrigation versus water-saving irrigation

Citrus fruit trees are sensitive to moisture, and from the perspective of high quality and abundant yield, all areas where citrus are planted should have water sources to solve the timely irrigation of plants when they need water.

Conventional irrigation refers to trench irrigation, watering, etc., usually with more water and more labor. With the development of citrus industry and the shortage of water resources, water-saving irrigation based on micro-spray and drip irrigation has been developed in citrus irrigation. The investment in water-saving irrigation construction is large, and the management requirements are also higher, but the use of labor-saving and water-saving, the effect of increasing the yield of citrus is obvious. It is advocated to use water-saving irrigation in gardens where flat land is concentrated, the relative slope of mountains is not large, and there are water sources that can use the height difference for artesian irrigation.

Mode selection

The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

Fine cultivation and light cultivation

Fine cultivation is a traditional cultivation method of mainland citrus production, aiming for high yield, and playing an active role in enriching fruit farmers and meeting consumer demand when citrus fruits are in short supply. Its cultivation characteristics are fine, labor-intensive, time-consuming, and the cost is correspondingly high.

With the rapid development of the citrus industry and the shift of rural labor to cities and towns, the price of agricultural inputs has risen, making it more difficult for fruit trees to continue to be finely managed. In the 90s of the 20th century, Chongqing introduced new varieties and advanced technologies of citrus from the United States, and carried out seedling cultivation, garden construction and management of soil (soil), fertilizer (material), water, protection (plant protection) and fruit (fruit) after planting in Chongqing Zhongxian County, experimented with American cultivation technology and achieved results, and some cultivation techniques were also promoted in citrus-producing areas across the country.

Zhejiang has continuously introduced Wenzhou mandarin varieties and a large number of mixed mandarin varieties from Japan, as well as corresponding supporting technologies, and then launched light and simplified cultivation technology after testing and summarizing citrus producing areas. Light simplified cultivation, also known as labor-saving cultivation, its main characteristics are to reduce labor intensity, reduce labor, and simplify technical operations.

Lightweight simplification can be implemented in terms of soil, fertilizer, plastic pruning, and pest control after citrus seeding.

Grass cultivation was introduced in soil management.

Fertilizer management is changed to apply 8~9 times a year to 2~3 times of fertilizer, and to dig holes (ditches) to apply chemical fertilizer to tree trays.

Plastic pruning, taking young trees that are not easy to shear and shape, let them grow, and then make appropriate plastic pruning as needed; The crown is sealed, and the large branches that are 3~4 years old are cut (sawed) to open a "skylight" to ventilate and transmit the crown.

Adopt green prevention and control in pest control: green prevention and control combining agricultural control, physical control, biological control and scientific chemical control, reduce the use of pesticides and protect the environment.

Another feature of light and simplified cultivation is to replace manual heavy labor with mechanization: mechanized tillage, mechanized weeding, mechanized fertilization, mechanized spraying, herbicide spraying, so that the labor intensity of cultivation management is greatly reduced, and the ergonomics are greatly improved.

Open field cultivation and facility cultivation

For a long time, mainland citrus has been cultivated in the open field in areas suitable for citrus cultivation in the south. A small number of protected areas (facilities) cultivation due to experimental and special needs.

Since the 90s of the 20th century, some production areas with low winter temperatures have carried out facilities cultivation based on plastic greenhouses, so that medium-ripe and medium-to-late ripening citrus varieties can successfully survive the winter, reach complete ripeness, delay harvest and obtain good returns. Facility cultivation is relatively large, but the benefits are obvious, the development is accelerated, and the cultivation of facilities with controlled temperature and humidity has been developed.

Postpartum options

The six choices faced by citrus cultivation, the right choice, citrus cultivation is easier

Post-harvest preservation and tree preservation

Postharvest preservation of citrus is the use of man-made technical measures to make the harvested fruit delay aging and maintain the inherent quality (appearance and internal quality) of its variety as much as possible.

It is mainly suitable for postharvest storage of medium-ripe and medium-to-late maturing varieties; Very early maturing varieties are harvested and sold, early maturing varieties can not be sold for a while after harvest (low price) for temporary storage, most of the late maturing citrus are picked and sold, and various storage places can be used for post-harvest storage, such as simple warehouses, underground warehouses, cellars and other storage, the method is the same as citrus storage (this omitted).

Some late-maturing varieties are harvested in spring in March ~ April, or even later, and it is impossible to sell them immediately after harvest, so they are stored in cold storage.

Cold storage is a modern preservation method using refrigeration and regulating gas, temperature and humidity equipment. When stored, the cold storage is kept at about 8 °C, the relative humidity is about 90%, the carbon dioxide concentration is below 1%, the oxygen concentration is 17%~19%, and the circulation ventilation is carried out regularly. The storage period of cold storage is 3~4 months, and the length can reach half a year, but the shelf life after leaving the warehouse is short, and it should be sold as soon as possible.

Retention tree preservation (also known as retention tree storage) is mainly the end of December to January ripe medium and late ripening citrus varieties, in order to delay the market to buy a good price, you can take the left tree storage until February, March or even later.

Post-harvest sales and fruit processing

Most of the early maturing varieties of citrus have achieved good benefits in the morning market, and are generally harvested on the market when they are ripe in August or September. Late-ripening citrus varieties that mature after February ~ March of the following year are usually selected for sale.

Fruit processing requires a large amount of citrus raw materials, so it can effectively alleviate the slow sales of citrus and promote the development of the citrus industry. The mainland citrus processing industry is mainly processing canned sugar water orange petals, the processing of citrus juice started late, compared with Brazil, the United States, etc., the gap is large, should vigorously develop orange juice processing, especially the processing of fresh orange juice.

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