(1) seedling raising
1. Rootstock seedlings should be cultivated on gentle slopes or irrigated paddy fields with convenient transportation, flat terrain, water source, slope below 5, soil with deep soil layer and good structure, sandy soil or soil with pH value within 5.5 ~ 6.5. Avoid water and air pollution and stay away from old citrus orchards. Rootstock requires the use of varieties or types that adapt to local conditions, have strong affinity with the main varieties, grow normally, have developed roots, have strong stress resistance, can bear fruit early after grafting, and have high and stable yield, high quality and no quarantine pests and diseases. Guangdong, Guangxi and Hainan sweet oranges, banana oranges and ponkan are mostly lime, vermilion orange (Jiangxi red orange) and red lemon. In recent years, Ponkan and Navel Orange both use Fructus Aurantii as rootstock, showing early fruit and high yield. Fujian red orange is used as the rootstock of wide-peel orange, and oranges can also be used as the rootstock of ponkan, banana orange and sweet orange. Most banana oranges and ponkan in Taiwan Province Province use lime and red stick lemon as rootstocks. Pomelo rootstocks in Guangdong, Guangxi and Fujian mostly use sour pomelo. Rootstock seeds are harvested from ripe fruits, and 6-8 petals are cut longitudinally with a special fruit cutting board or knife to squeeze out the seeds. Then put it into bamboo radish or coarse cloth bag, add a small amount of plant ash, gently knead it, and then rinse it with clear water to remove the pomace and pectin in the seed coat. Spread the washed seeds in a cool and ventilated place and sow when the seed coat turns white. It is best to sow seeds fresh, otherwise they should be stored in dry storage or sand storage. Seed content and sowing amount of rootstock fruit. Sowing ground should be intensively cultivated, fully plowed and harrowed, and evenly applied with sufficient base fertilizer. Generally, 3750-4500 kg of pig manure, cow dung, high-quality compost, 225-375 kg of calcium superphosphate and 375-450 kg of lime are applied per hectare. There are two sowing methods: sowing and drilling. After sowing, the seedbed soil should be kept moist, and the seedlings should grow 3-4 true leaves. After that, thin water and fertilizer should be applied, and attention should be paid to the prevention and control of anthracnose, damping-off disease and leaf miner. There are two kinds of rootstock seedling transplantation: new seedlings and old seedlings. The newly planted seedlings are sown in the first winter and the second spring, transplanted with a spacing of 20cm× 12cm from May to mid-July of the following year, grafted in winter and spring, and taken out of the nursery in autumn. The whole seedling raising time is two years. This method should strengthen the management of fertilizer and water, make the rootstock grow rapidly, and then leave the nursery in time. Transplanting old seedlings in autumn and winter of the following year or spring of the third year according to the row spacing of 25cm× 12- 15cm; Spring sowing should be transplanted in autumn and winter or in April-May of the following year when the buds are mature. After growing for 9- 1.5 months, grafting is carried out in winter and spring, and the whole seedling raising time is two years.
Grafted seedlings can be cultivated all year round, but they are the best before the spring begins. Grafting can be done early when the branches are full in winter, otherwise it will be delayed. In order to raise seedlings quickly, grafting can also be carried out in summer and autumn, and it should be carried out in sunny and warm days. It is not suitable for grafting in rainy days when the soil is too wet and in windy weather. It should be avoided in rainy days and when the sun is strong at noon. Grafting methods Guangdong, Guangxi, Fujian, Hainan and other places mostly use single-bud cutting grafting or single-bud abdominal grafting, and the survival rate is over 90%. Grafted seedlings should be reshaped in nursery, mainly to determine the height of trunk and cultivate a certain number of trunk branches. And promote the growth of autumn shoots by cutting off the top of summer shoots. Topping in hot areas is generally carried out around beginning of autumn, where the cold dew wind comes early, and places that are prone to drought or leave the nursery in late autumn and early winter can be advanced appropriately. In the middle and upper part of the first summer shoot, select the part with uniform internodes and complete leaves, and cut the top 25-30cm from the ground. If the spring shoots exceed this height, cut them off. After cutting the top, remove the scattered autumn shoots that spit early in time. Most seedlings have 3-6 buds before sprouting to maintain the balanced growth of branches. When the buds grow to about 3cm, select 3-5 strong main branches which are evenly distributed in all directions, and pull out the rest in time. The criteria for excellent grafted seedlings are: excellent and pure varieties, no Huanglongbing and quarantine diseases, stout branches, good joint healing, height of newly planted seedlings above 10cm (height of old planted seedlings above 50cm), stem diameter above 0.8cm, 3-5 main branches, dark green and shiny leaves, and main root length above 15cm.
3. Virus-free seedlings are cultivated in high temperature and humidity, and citrus diseases, especially dangerous diseases, are a great threat. Cultivating virus-free seedlings is an important way to solve this problem. The main methods are:
(1) The heat-treated rootstock seeds are treated with hot water at 56℃ for 50 minutes, the scions are treated with steam at 50℃ for 45 minutes, and the seedlings before spring automation are treated with steam at 49℃ for 50 minutes.
(2) soaking the scion treated with antibiotics with streptomycin 700u/ml solution lh; Tetracycline 1000 u/ml solution for 2 hours; If tetracycline 1000u/ml solution is heated to 46℃, the soaking time can be shortened to 20min minutes.
(3) Shoot tip culture Using tissue culture technology, after Yuan Ye's basal part was removed from the shoot tip of the scion variety, the shoot tip (cone meristem without vascular tissue) of about 0. 1-0.2mm was taken and placed in a suitable culture medium for seedling raising.
(4) Micro-grafting uses heat treatment and test-tube seeding to cultivate seedlings of toxic rootstocks, and then puts potted seedlings of scion varieties in an artificial climate chamber (30-40℃) for 2-4 weeks to promote the generation of new buds. When the new bud grows to a few centimeters, take it.
(2) Building a garden
1. Establishment of Citrus Orchard on Slopes Citrus is planted in mountainous and hilly slopes in Fujian, Guangxi and the central and northern parts of western Australia and eastern Australia in Guangdong. Choose a gentle slope below 10-30 (preferably below 10), and the south subtropical zone is best inclined to the southeast or northeast to the north or northeast of the tropical zone. Should be close to the water source, convenient transportation, away from the old citrus orchards or other rutaceae plants. Then, garden planning is carried out, including plot division, road and irrigation and drainage system planning, soil and water conservation engineering planning and windbreak forest setting. Large orchards take the same slope direction of 2-3m2 as a plot. In mountainous areas with large slope and complex terrain, the plot can be approximately rectangular, which can be used for soil and water conservation and mechanized farming. Generally, the main roads of large orchards are 6-8m wide and the branch roads are 3-4m wide. The roads in this area are l-2m, with longitudinal roads every 50- 100m and transverse roads every 20-30m. Irrigation and drainage system includes three types: contour flood control ditch, longitudinal ditch and contour transverse drainage ditch (storage ditch). The contour flood control ditch is located above the sloping orchard with a depth of 60- 100cm and a slope of 0. 1%-0.2%, which is connected with the longitudinal ditch. The longitudinal groove is 50-60 cm wide, the transverse groove is 20 cm deep and 25-30 cm wide. On the inner side of the cross road and the inner side of the step surface, solid mounds less than the ditch surface 10cm are reserved at intervals of 2-3 m, so as to discharge excess water. Soil and water conservation project is to open terraced fields with a slope greater than 10, and open ditches with a slope less than 10, and various gentle slopes can be made according to contour lines. The effective range of shelter forest is about 20 times of the height of shelter forest, the main shelter forest is not less than 4 rows, the gentle slope land is not in the windward direction, and the slope land and hillock land are built on the watershed of slope or hillock top. The auxiliary forest belt family 1-2 rows of trees are located at the edge of the road irrigation and drainage system and pond in the park. Contour terraces are the best form of soil and water conservation in sloping citrus orchards. The width of terraced fields is determined according to the slope when the garden is opened. Generally, terraces with large slopes are planted in a single row, and the width of terraces is 3-4cm. Terraces with smaller slopes are more than 6m wide, and generally two or more rows can be planted. The slope below 5 can be planted by contour ditch method.
2. To establish flat orange orchards in Chaoshan Plain, Pearl River Delta, Fujian, Guangxi and other hot areas along the river (dry land or dam land), sandy loam or loam with high terrain, rich water resources, loose structure and rich organic matter should be selected for orchard construction. The irrigation and drainage system should be well planned in the paddy field citrus orchard, and its main forms are:
(1) Deep furrow ridge type is widely used in small orchards with high water level, heavy waterlogging and difficult irrigation and drainage. There are two methods: ① Ditching according to row spacing, separating the main border from the intercropping border, and shallow border (depth 1.5cm, width 30cm). When citrus is planted, the root neck ratio is higher than the border 10cm. After that, the soil at the intercropping border and the bottom of the ditch will be dug up year by year, covering the border in winter, and the border will continue to rise. After 3-4 years, the ditch depth is 45-70cm, and it will reach 1 m or more after 8 years.
(2) The plain area with high water level and large area adopts three-stage irrigation and drainage. It is characterized by three-stage irrigation and drainage ditches, which gradually expand and deepen. The width of the border is 50cm and the depth is more than 33cm; The surrounding ditches are 67 cm wide and 50 cm deep. There is a water inlet above and a water outlet below to connect the drainage ditch. The depth of the drainage ditch is twice that of the surrounding ditches, and the depth and width are about 100- 134cm, leading to the main drainage ditch, i.e. the gravity irrigation network.
(3) Low-border dry ditch type is used in paddy fields with low water level, loose topsoil and convenient irrigation and drainage. The advantages are low border, low value, labor saving, easy management, convenient irrigation and drainage, fast growth and early fruiting of citrus after planting. Disadvantages are that the root groups are not deep, water is easy to accumulate in rainy season, and the life span of citrus trees is slightly shorter.
3. The beaches, river dams and coastal beaches in Fujian and Guangdong have high sediment concentration, poor water and fertilizer conservation, fast heat absorption and heat dissipation, rapid and large water evaporation, lack of organic matter and poor soil fertility. In these places, windbreaks should be built first, and then soil should be improved to increase soil and organic matter to meet the requirements of citrus growth and development. The dam is a good place to grow citrus because of its deep soil layer, rich groundwater, tall trees, high yield and long life. However, it is vulnerable to the threat of flood, so attention should be paid to flood control when building the garden, and ditches should be dug to eliminate stagnant water in rainy season.
4. Planting is mostly in spring and autumn. Spring planting is carried out before the spring buds germinate (after the great cold and before beginning of spring). At this time, the weather is dry, suitable for water irrigation in high temperature areas. It can also be done around Grain Rain, after the spring buds mature and before the summer buds spit out. At this time, the temperature gradually rises, which is suitable for the growth of citrus roots, with more rain, less light and less evaporation, and the survival rate is high after planting. Mountainous areas lacking water will be planted during this period. Autumn planting should be carried out after the autumn shoots mature (around "Bailu" to "first frost"), and autumn planting is best in places with good irrigation conditions. Because of the short sunshine, weak sunshine and reduced evaporation, the soil temperature is suitable for rooting. After planting, under the condition of sufficient irrigation, the growth will recover quickly, and the new buds will germinate neatly in the second year, and the buds can be released 4-5 times a year. The planting density of citrus varies with rootstock, variety, cultivation environment and management level. The planting density of tree rootstock (lime or tangerine) on sloping land can be 3m×5m, with 660-900 trees/hm ㎡; The density of lime rootstock should be increased by 5m× 5m in the place where the groundwater level is low. 400-900 plants /hm ㎡, semi-arbor rootstocks (Jiangxi red orange and red lemon) and semi-dwarf rootstocks (bitter orange rootstocks). In paddy fields with high groundwater level, the planting density can be doubled, about 1500- 1800 plants /hm2.
Orchards on hilly slopes are fixed according to plant spacing, and planting holes with a depth of 80cm and a width of 1m are dug. After weathering for a period of time, the base fertilizer is filled in layers. Put 30-40 kilograms of green manure and weeds on the bottom layer, sprinkle 0.2 kilograms of lime and cover the topsoil; 30-40 kg of semi-decomposed weed compost is placed in the middle layer, 0.2 kg of lime is sprinkled and the topsoil is filled; Put 20-30 kilograms of manure or garbage manure on the upper layer and cover it with topsoil. The fill should be 20-30cm higher than the ground, and it will be just flush with the ground after the green manure decays and the loose soil gradually sinks. Before planting, 5- 10kg of garbage, pig, cow dung or compost per plant. 0.25-0.5 kg peanut bran, 0.25-0.5 kg lime and 0. 15-0.25 kg calcium superphosphate are mixed and fermented for 20-30 days before application.
If the water level in the flat orchard is not high, shallow holes should be opened to backfill fertile soil and apply base fertilizer for planting. If the groundwater level is high, piers or ridges should be built before planting. The height of a pier or ridge depends on the groundwater level.
Planting methods are divided into soil transplantation and soilless transplantation. In production, transplanting without belt is the main method. Choose cloudy and windy days for planting. When planting, after putting the seedlings into the planting hole, correct the plant position by planting board or visual inspection, and then straighten the root system and fill it in the fine soil, so that the root system can be in close contact with the soil. The marriage interface should keep the soil heavy and still be exposed on the ground. After planting, spray enough water to fix the roots, cultivate the planting holes into piers with a height of about l5-30cm and a diameter of 60- 100cm, and then cover the trees with weeds. If it doesn't rain after planting, water it once a day for 3-4 days to keep the soil moist. After one month, you can apply thin water and fertilizer and pay attention to insect prevention.
(3) Orchard management
1. Soil management
(1) Soil management of citrus orchards in hilly and mountainous areas In hot areas, the soil on hilly slopes is barren, with little organic matter, strong acidity, poor structure, easy erosion, loss of fertilizer and water, and easy drought in dry season. Therefore, the following soil management work must be done well after planting: ① Expanding the hole and pressing green manure to improve the soil: from the second year to the third year after planting, dig a ditch with a width of 30-50cm around the planting hole once a year and press green manure to improve the soil. It is best to feed for a long time in May -65438+ 10, and to strengthen trees in September or June-01-65438+February after autumn shoots mature. (2) Intercropping: Young citrus orchards with fertile soil and sufficient water, labor and fertilizer can be intercropped with leguminous crops such as peanuts. If the soil quality is poor and the fertility is insufficient, you can interplant coarse green manure, and the intercropped crops should not be too close to the trees. For young trees 1 ~ 2 years after planting, 1.0- 1.5m should be reserved. ③ intertillage, mulching and ridging: intertillage 3-4 times a year, after rainy season 1 time, after fruit picking in winter 1 time, with a depth of l0- 15cm, without breaking soil, shallow intertillage 1 time before and after Tomb-Sweeping Day, or combined with intercropping. The depth of intertillage is generally 15-20cm, and the closer to the village trunk, the shallower the intertillage, so as not to damage the big roots. Intertillage is usually combined with weeding. In order to save labor, chemical weeding can also be used ④ Covering: Covering can be divided into two types: dead tree tray covering and whole garden covering. Generally, it is covered with a tree disk, and the thickness depends on the amount of materials, generally 10- 15cm. The cover should keep a certain distance from the trunk to prevent longicorn beetles from laying eggs. ⑤ Soil cultivation: After picking fruits in winter, before cultivation, dig the topsoil 25cm away from the trunk to a depth of about 10cm, then cultivate each plant with 40-50kg soil miscellaneous fertilizer, and then cultivate 200-300kg weathered pond mud, river mud or mountain soil.
(2) In addition to intercropping and intertillage, the emphasis of soil management in flat citrus orchards is soil cultivation and restoration of irrigation and drainage systems. When cultivating soil, local materials are used, mainly dry pond mud, river mud, field mud, turf throwing and ditch mud, each plant is 100-200kg per year, which are scattered on the border. After a year of soil ploughing and rain erosion, the original irrigation and drainage system appeared shallow siltation in the ditch, which affected irrigation and drainage. Thoroughly clean up in winter, lower the water level, and ensure smooth drainage and irrigation in the coming year.
2. Nutrition and fertilization The growth and development of citrus need a variety of nutrients. According to the demand of citrus trees in different periods and soil fertility, scientific fertilization is an important work in orchard management to achieve early fruit, high and stable yield, high quality and long life.
(1) Nutritional elements and their main functions required for the growth and development of citrus. Citrus needs a lot of elements such as nitrogen, phosphorus, potassium, calcium, magnesium and sulfur, and a few essential nutrients such as iron, manganese, copper, boron, zinc and aluminum.
Nitrogen (N) is an important element in protein (the nitrogen content in protein is 1O%- 18%), and it is also the main component of chlorophyll. When nitrogen is insufficient, the growth of new shoots is short and weak, the leaves are small, the leaves are yellow and thin, the fruit setting rate is low, the fruit quality is poor, and the trees are precocious. Phosphorus (P) is the main component of hyaluronic acid, nucleoprotein, lecithin and enzyme, and it is also the substance of energy conversion in absorption and metabolism. Phosphoric acid plays an important role in photosynthesis, respiration and energy metabolism. The growth of new shoots and roots is weakened due to lack of phosphorus, the leaves become narrower, and the old leaves lose their luster, changing from dark green to bronze, causing early defoliation, thickening of pericarp and increasing acid content of fruits. Potassium (K) mainly exists in the stems and leaves of citrus, especially in the tender parts. Potassium can make cell colloid swell when it meets water, which is beneficial to metabolism, reduce evaporation, improve the intensity of photosynthesis and the synthesis of sugar. When potassium is insufficient, the new shoots are weak, the growth stops early, the fruit becomes smaller and sour, the peel becomes thinner and easier to crack, and the storage stability of the fruit becomes worse after maturity. Calcium (Ca) is the main component of cell wall pectin, which is necessary for the apical meristem to continue to grow. Calcium deficiency first damages the growing point, especially the root tip. The root system is stagnant, not resistant to hypoxia, weak in moisture resistance and antibacterial activity, and easy to rot. The new shoots are short, weak and wither early, and the shoots are often clustered. Leaf yellowing first appeared at the edge of the leaf and gradually spread to the veins. In severe cases, the main veins turn yellow, and sometimes tiny dead spots appear on the leaves. Calcium-deficient plants have many flowers, serious fruit drop, low yield, slightly sour fruit, shrinking juice cells and incorrect fruit shape. Magnesium (Mg) is a component of chlorophyll and also participates in the biosynthesis of phosphorylated substances. When magnesium is deficient, the magnesium of the old leaves first transfers to the tender tissues, and the old leaves below the new shoots appear yellowing symptoms, and the chlorophyll between the veins fades, and an inverted "V"-shaped yellowing zone appears from the tip of the leaves, and the leaf base only maintains a triangular green zone. Zinc (Zn) is a component of carbonic anhydrase in citrus plants and plays an important role in photosynthesis. Zinc is also involved in the formation of various biotin in plants. Therefore, when zinc is deficient, the leaves on the new shoots become significantly smaller, narrower and more upright. The main lateral vein and its vicinity are green, the rest are bright yellow-green or yellow with flower-like leaves, and then cinnamon dies. When zinc is deficient, abnormal flowers and degenerated flowers increase, the bud drop is serious, the fruit setting rate is low, the fruit is small, the skin color is light when mature, the pulp juice is less and tasteless, and the yield is reduced. Manganese (Mn) is a component of oxidoreductase in plants, which plays a great role in the formation of chlorophyll and the accumulation and transportation of sugar in the body. The symptoms of manganese deficiency leaves are similar to zinc, but the yellowing part of manganese deficiency leaves is dark green, and the size and shape of leaves are basically normal. Boron can promote the transport of carbohydrates, which is closely related to the growth and development of meristem and reproductive organs. When boron is deficient, the leaves bend backward, the veins are slightly swollen, the back of the leaves has yellow stains, the old leaves lose their luster, the main and lateral veins are seriously broken, and the leaves are easy to fall off. At the early stage of boron deficiency, young fruits appeared milky white and slightly convex spots. In severe cases, sunken black spots will appear. If you cut the cross section of the fruit, you can see that the white mesocarp and core have yellow and yellowish brown colloidal substances, resulting in a large number of fruit drops. Molybdenum (Mo) is an essential element of nitrate reductase (Al-flavoprotein), which can also increase photosynthesis, phosphatase activity and vitamin C synthesis in vivo. When molybdenum is deficient, water stains first appear between veins in early spring, and then spread to macular symptoms. In severe cases, the whole tree falls off, and the fruit appears irregular brown spots with yellow halo. Whether it is leaves or fruits, there will be more diseased spots in sunny parts. In summer, leaves will turn into dark brown necrotic spots and crack into holes after gumming. Molybdenum deficiency is easy to occur in acidic soil. Iron (Fe) is mainly involved in enzyme activity and is an essential element for protein synthesis during chloroplast development. When iron is deficient, the mesophyll of buds and new leaves is yellow and white, the veins are green, the skin is yellow, and the fruit tastes light and sour.
(2) The deficiency of nitrogen, phosphorus, potassium and calcium in citrus element deficiency disease can be corrected by applying corresponding fertilizers to the soil. When magnesium is deficient, magnesium fertilizer can be properly applied on the basis of organic fertilizer in the soil, or 1% magnesium sulfate can be sprayed once a day from the young fruit stage to the rapid fruit expansion stage. When zinc is deficient, 0.4% ~ 0.5% zinc sulfate can be sprayed before spring shoots germinate, and 0. 1%-0.2% zinc sulfate 1-2 times after germination, or it can be applied in slightly acidic soil with base fertilizer, and zinc sulfate 100- 150g can be applied to each plant. Lime and organic fertilizer should be applied to the soil with high acidity to improve the buffering property of the soil and increase the content of available zinc in the soil. Manganese deficiency can be mixed with manganese sulfate and other fertilizers in acidic soil. Alkaline soil can be sprayed with mixed solution of manganese sulfate and quicklime (0.2% ~ 0.5% manganese sulfate plus 1% ~ 2% quicklime). Under the condition of boron deficiency, 0. 1%-0.2% boric acid solution or borax solution 1-2 times can be sprayed from spring shoot germination to full flowering stage. Lime should be properly applied to the soil with strong acidity, and farmyard manure with high boron content such as plant ash and Green Manure (Jin Juhua) should be applied. Molybdenum deficiency can be corrected by adding lime and spraying 0.0 1% ammonium molybdate. Spraying 0. 1%-0.2% ferrous sulfate 1 time every half month and applying more organic fertilizer to correct iron deficiency during the growth period of new shoots. Because citrus orchards in tropical areas often use chemicals containing sulfur and copper, citrus has no symptoms of sulfur deficiency or copper deficiency.
(3) Fertilization of citrus trees
① Fertilization period 1 ~ 2-year-old young trees, focusing on cultivating each branch. The principle of fertilization is to apply thin fertilizer to Corydalis, and apply more fertilizer before and after bamboo shoots. After planting for one month, the new roots begin to move, and thin water and fertilizer can be applied. Apply quick-acting fertilizer once before new shoots germinate 10- 15d and once during the new shoots stop growing period, and strive to sprout healthy new shoots 3-4 times a year. First-bearing trees (3-4 years old) should be replanted in winter, before spring and before autumn. The principle of doing nothing before summer. That is, from February of 65438 to February of the following year, 65438+ 10, the fruits were picked and fertilized to meet the needs of spring shoots, with late-acting fertilizer as the main fertilizer. In February, no flourishing trees were applied before the spring shoots, and quick-acting water and fertilizer were applied to weak trees once to promote the growth of spring shoots. No fertilizer was applied from May to June to control the growth of summer buds. Re-application before autumn, mainly with quick-acting water and fertilizer, aims to promote autumn shoots and lay a good foundation for increasing production in the next year. Apply 1-2 quick-acting water and fertilizer from August to June to strengthen shoots and fruits. Fruiting trees in prime years are fertilized 4-5 times a year, mainly before and after fruit picking, before spring shoots and before autumn shoots. Late-maturing seeds, middle-maturing seeds with many fruits and weak fruit-bearing trees should be applied before fruit picking; Early-maturing seeds and middle-maturing seeds with low fruit yield should be applied after fruit picking. Ponkan is best applied before fruit picking, and citrus orchards with little rain and no irrigation conditions should also be applied early, mainly with quick-acting fertilizer to restore tree vigor and protect leaves for winter. Apply quick-acting water and fertilizer 15d before the spring shoots germinate to promote the spring shoots to grow well, or apply fertilizer twice before and after germination. Apply quick-acting fertilizer once before and after the summer heat, that is, before the autumn shoots germinate15 days to promote the growth and health of autumn shoots. Around 10, the fruit entered the peak growth period, and the tree body began to enter the physiological differentiation period of flower buds. Applying high-quality fertilizer once is beneficial to fruiting and flower bud differentiation. In addition to the above fertilization, the age, vigor, flowering amount and leaf color of the tree should be considered in the full flowering period or withering period, and withering fertilizer should be applied appropriately. For trees with light leaves and many flowers, available nitrogen fertilizer can be applied once more; Trees are vigorous, with thick green leaves or few flowers, so as to avoid excessive growth and fruit drop in summer shoots. May-June is the development stage of young fruit. If there are many fruits, pale leaves and insufficient buds, quick-acting fertilizer can be applied once. For citrus planted on high dry land or older trees, summer shoots are the fruiting mother branches in the second year, so it is necessary to apply quick-acting water and fertilizer at one time to promote summer shoots.
② There are two fertilization methods: rhizosphere fertilization and external fertilization, and the location of rhizosphere fertilization is around the drip line outside the crown. In order to make the roots grow deeper, the citrus on the slope should be furrowed and fertilized. Small trees should be ditched, and big trees should have half-moon or long ditches on both sides. Every fertilization should rotate and gradually move outward with the expansion of the crown. Topdressing should be applied lightly, and the depth of fertilization hole is about 10- 12cm. Water fertilizer or urea should be applied in the growing season, and the depth is about 3-5cm. Base fertilizer should be deeply applied once a year, and deep roots can be cultivated with deep ploughing and soil improvement. Fertilization should not be over-concentrated, bran water and human and animal manure should be fully decomposed to avoid damaging the root system, and the soil should be restored after fertilization. The withered root system of citrus in paddy field is shallow, so it can be watered and fertilized under the tree tray. In the future, with the expansion of the crown, the fertilization position will gradually move outward, using shallow application or splashing application.
Topdressing outside the roots should be carried out on cloudy days or in the evening, and 88% urea can be absorbed 24 hours after spraying.
(3) Nutritional diagnosis and proportional fertilization have become an important means to realize the modernization of fruit production through comprehensive analysis of morphological diagnosis, leaf analysis, soil analysis, metalloenzyme activity determination and fruit analysis. According to the analysis of Fruit Research Institute of Guangdong Academy of Agricultural Sciences, ponkan leaves contain 2.7%-3.3% nitrogen, 0. 12%-0. 15% calcium10%-10.8% magnesium. Guangxi Citrus Research Institute thinks that the leaves of sweet orange contain 2.5% ~ 3.0% nitrogen, 0. 12% ~ 0. 18% phosphorus and 0.1.7% potassium. According to the analysis of Fujian Institute of Subtropical Plants, the suitable leaf content for high yield of Guanxi honey pomelo is 2.5%-3. 1% nitrogen. 0. 14%-0. 18% phosphorus, 0. 14%-0.2% potassium, 2.0%-3.8% calcium, 0.32%-0.47% magnesium and 8.0-1copper. . In terms of fertilization, according to the experiment in hot province, the ratio of nitrogen: phosphorus: potassium is 1: 0.5: 0.8- 1. The annual tree of sweet orange 1-2 is1:0.4: 0.2; 3-4-year-old fruit trees are1:0.7: 0.6; 5-6 years old is1:0.5: 0.7; The fertilization ratio for 7-year-old and above is1:0.5-0.6: 0.8; 1: 0.5: 0.6 is suitable for more than 10 years, and can be appropriately adjusted according to soil fertility, tree potential and fruiting conditions in various places.
④ Fertilization amount The fertilization amount depends on tree age, tree vigor, fruit yield, soil fertility and fertilizer types. In Chaoshan, Guangdong, annual trees are applied with 300-450kg urea, 225-300kg phosphate fertilizer and 0/500-2250kg manure/kloc; Two-year-old trees were treated with 450-600 kg urea, 600-750 kg bran fertilizer and 3000-3750 kg manure. After three years, there were differences among different varieties. According to the statistics of Fruit Research Institute of Guangdong Academy of Agricultural Sciences, if the yield of improved orange ("Hongjiang orange") is 65,438+05 kg in 3-5 year-old medium fertility orchard, the annual application of pure nitrogen is 0.65,438+08-0.20 kg, and the annual application of pure potassium is 0.2-0.225 kg. Zhuang, Fujian et al. (1988) reported that the annual application of nitrogen and phosphorus (p2o 3) 195-225.
450kg is appropriate.
3. The irrigation and drainage period is determined according to the water demand of citrus phenology, soil water content and local climate conditions. In spring, citrus germination needs a certain amount of soil moisture to ensure the orderly and normal growth of spring shoots. At this time, in case of drought, appropriate irrigation should be carried out to keep the soil moist. There is a lot of rain in summer, especially in flat orchards, which should be mainly drained. However, in case of 7-8 days of high temperature and dry weather during the physiological fruit drop period in early summer, irrigation should be done properly to avoid a large number of fruit drops. Autumn is the period when autumn shoots (fruiting mother branches) and fruits expand rapidly, which requires a lot of water. Autumn drought causes insufficient soil moisture and must be irrigated in time. Fruits continue to grow in early winter, and irrigation is still needed in case of drought, but water should be properly controlled during flower bud differentiation. Late-maturing varieties (such as summer orange) should maintain the most suitable soil water content throughout winter, and irrigation should be carried out when the soil field water capacity is lower than 60%. During irrigation, the soil moisture in the root system of Shatian pomelo should reach the most favorable level for growth and development, which is equivalent to 60%-80% of the maximum soil water capacity. Irrigation methods should be irrigation, furrow irrigation, flood irrigation, sprinkler irrigation and drip irrigation. According to water source, soil quality and input. If the water source is insufficient, manual or hose irrigation should be used. Orchards with sufficient water sources and perfect irrigation ditches can use natural water sources or electromechanical pumping to open up water diversion irrigation. The tree crowns have basically crossed, and the garden can flood the whole country if it is flat. After irrigation, the garden soil is slightly dry, that is, shallow harrow is used to conserve moisture. There are two types of sprinkler irrigation, mobile and fixed, and it is better to have the same type. In the sprinkler irrigation garden, the pipeline connecting the water pump is buried underground, and a vertical spray pipe is set at regular intervals, and a spray bucket is installed on the pipe for aerial spraying. Drip irrigation is to set a drip irrigation device at the tree tray, which is the most economical way to use water.
Step 4: plastic trimming
(1) young tree shaping pruning young tree shaping is to lay a good foundation for cultivating early-bearing, high-yielding, stable-yielding and long-lived crowns. After planting, all young trees with upright branches should be pulled out, that is, when the new buds sprout in spring after planting, the branches with small branching angles should be pulled out to more than 45 degrees with a string, and then loosened when the new buds mature, so that the branches can be restored to 45 degrees. In most citrus producing areas in hot areas, neat and strong summer and autumn shoots are cultivated by wiping buds and controlling shoots. The specific method is to wipe the buds every 3-4 days after the top buds of scattered branches germinate, stick to15-20 days, and let the buds germinate (let them germinate freely) until most branches of the whole tree germinate 3-4 new buds. Pruning young trees is mainly to control summer shoots and cut off long branches and weak winter shoots. A large number of summer shoots often cause fruit drop, and fruit drop is controlled by wiping buds. Summer shoots can't be released until the cross diameter of fruits is about 3cm (different varieties) and the seeds meet. In addition, in summer or winter, drooping branches and long branches and weak winter buds should be cut off.
(2) Pruning of adult fruit trees has strong light in hot areas, and most varieties have certain fruiting ability in the crown. Generally, the pruning method of "short cutting and harvesting, topping and removing hegemony, thinning outside and repairing inside" is adopted. The main objects of shortening are fruiting branches (several fruits are concentrated on one branch), falling flowers and fruiting branches, and various declining branches in the periphery of the middle and upper parts of the crown. Leave 5 ~ 10 cm for retraction and pruning, and leave branches and piles to spit out new buds. The thickness of cutting day depends on the age of the tree. In summer, the high temperature and high humidity hair tips are vigorous, and the cutting thickness is 0.5-0.8cm. In winter and spring, the ability to germinate new shoots at low temperature is not as good as that in summer, and the cutting diameter is generally 0.8- 1.2cm. After the tree is old or high-yielding, the branches that begin to decline at the top of the crown are compressed and pruned, and some overgrown branches at the top of the crown of mature trees are pruned from the base without leaving branches and piles. External thinning and internal consolidation are the proper thinning when the branches outside the crown are too dense and the trees cross to shade in winter, so that the sun can penetrate into the inner room; Try to keep the branches facing the inside of the crown, and only trim some branches that are excessively shaded, delicate and have thin leaves, so as to enhance the fruiting ability of the inside and bottom of the crown. During pruning, Guangdong and other provinces promote pruning twice a year, 20 days before summer pruning 15- autumn shoot release, in order to promote vigorous fruiting branches and winter pruning after fruit picking.