Origin and distribution
Most oriental pears are native to China. According to the Book of Songs, "236,200 trees have branches", it has a cultivation history of at least 3,000 years. Pears and bamboo slips dating from 2 100 years ago were unearthed from Mawangdui Han Tomb in Changsha, Hunan Province. By the 6th century AD, pear cultivation and management experience had been quite rich. The Book of Qi Yaomin described in detail the propagation method of pear "inserted pear" (grafted pear). Since19th century, pears from China have been introduced and cultivated in Europe, America and Japan.
Western pears are native to central and southeastern Europe, Caucasus, Asia Minor, northern Persia and other places. The remains of wild pears were found in the Neolithic site of "Lakeside Residence" in Switzerland. Ancient Greece clearly distinguished the wild species and cultivated species of pears, and described the cultivation methods of pears. Six pear varieties were recorded in Cato (M.P.Cato, 235 ~ 150 BC) in Roman times, which shows that western pears have been cultivated in Europe for more than 2,000 years. The early cultivation of western pears in Europe developed slowly. /kloc-After the 6th century, the number of cultivated pears increased gradually due to the cultivation of more excellent varieties. After 1630, European immigrants introduced it to the United States for planting. Japan was introduced from the United States in 1872 ~ 1873, but the cultivation amount was small. Western pears have been cultivated in China for over 100 years. 1870 or so, American pastor JohnL. Norris introduced seedlings for trial planting in Yantai, Shandong Province. Due to the suitable local conditions and good growth, it has gradually been planted equally in Yantai, Fushan and Mu, becoming the main producing area of western pears in China.
Pear is also one of the main fruit trees in the world, distributed in all continents, with the largest output in Asia and Europe. 1988 See table 1 for the output of major pear producing countries in the world.
Table 1 The cultivated area and yield of pears in China are second only to apples. All provinces (autonomous regions) in China are distributed. Hebei, Shandong and Liaoning provinces are the concentrated pear producing areas in China, accounting for about half of the cultivation area and 60% of the output, of which the annual output of Hebei Province accounts for about 1/3 of the whole country.
Features and characteristics
Pear varieties are different, but they all have the same characteristics in morphological characteristics, growth and fruiting habits and phenology.
morphological character
The trunk bark is smooth at the young tree stage, and it thickens, cracks or peels off longitudinally with the growth of tree age. The shoots are hairless or have fine hairs, and then fall off; Branches over 2 years old are grayish yellow or even purplish brown. Winter buds are covered with tile-like scales, generally 1 1 ~ 18, with or without fluff; Flower buds are plump, brownish red or reddish brown, slightly bright, generally mixed buds; The leaf buds are small, sharp and brown. Simple leaves, alternate, serrated, stipules fall off early, tender leaves are green or red, and turn green after unfolding; Most leaves are oval or rectangular, with petioles of different lengths. Flowers are corymbose flowers, bisexual flowers, each inflorescence is generally 5 ~ 10, white, and a few are pink; Corolla 5 petals, petals suborbicular or broadly elliptic, sepals open or inverted; Stamens are 20 ~ 30, and anthers are often red or purplish red; Cultivars have 3 ~ 5 styles, 3 ~ 5 ovary chambers, and 2 ovules in each chamber. Fruits are round, oblate, oval and spoon-shaped. Pericarp can be divided into two categories: yellow or brown, and some yellow varieties are red in front; The fruit stalks of Qiuzi pear and Xiyang pear are thicker and shorter, while those of Pak Lei pear, Shari pear and Xinjiang pear are generally longer. Sepals of Pak Lei fall off, and sepals of foreign pears, sand pears and Xinjiang pears remain, remain or fall off; There are stone cells in the pulp and cartilage in the endocarp; Seeds dark brown or nearly black.
Growth and fruiting habits
Pears have a long life span, which can reach 100 years or more. The root system is developed, the vertical root depth can reach more than 2 ~ 3 meters, and the horizontal roots are widely distributed, which is about 2 times of the crown width, and a few can reach 4 ~ 5 times.
Pear has a strong sense of dryness and obvious layering. The central leading branch of young trees has obvious advantages, and it is easy to produce strong upper branches and weak lower branches; Most branches grow upright and the crown is conical. As a result, they gradually expand into a round head or a natural semicircle. The formation of buds is generally not easy to germinate in the same year; The germination rate of buds is high, and the branching ability varies with varieties, which is generally low. Almost all obvious buds of 1 year-old branches can germinate and shoot, but the number of shoots and shoots is very small. Generally, the first branch on the top grows vigorously, and the second and third branches weaken obviously in turn, and most of the branches below become medium and short branches. The new shoots of pear stopped growing earlier, and there were few secondary growth except young trees. In subtropical areas such as Guangdong and Yunnan, due to high temperature and abundant rainfall, 1 year can grow three times. Pear has many hidden buds and long life. After aging or damage and some stimulation, the branches can germinate and sprout.
Pears bear fruit early and have a long fruiting period. Some varieties begin to bear fruit in 2 ~ 3 years, and the complete fruiting period can reach more than 50 years. Fruit branches are divided into short fruit branches, medium fruit branches and long fruit branches according to their length. Flower buds can be divided into terminal flower buds and axillary flower buds, and the terminal flower buds are mainly fruiting. Most varieties are mainly short fruit branches, and some varieties gradually form fruiting branches after bearing fruit. The fruiting branches have a long life, which can last for 10 years and still bear good fruits. Most pear varieties bloom first and then spread their leaves, and a few varieties have flowers and leaves open at the same time or spread their leaves first and then bloom. In an inflorescence, the flowers in the middle bloom first, and the flowers in the center bloom later; The fruit setting rate of the top flower bud is higher, but that of the axillary flower bud is lower (see figure).
After the pear pollen is fertilized, the fruit begins to develop, the receptacle develops into flesh, the ovary develops into nucleus, and the ovule develops into seed. In the process of fruit growth and development, the early stage is mainly cell division and tissue differentiation, and the later stage is cell expansion and pulp maturity. The fruit volume growth curve is S-shaped. The flower bud differentiation period of pear is from early June to early September. Generally, short fruit branches are earlier than medium-long fruit branches, and terminal buds are earlier than axillary buds. Adult trees are earlier than young trees and vigorous trees. The root growth of pear has two growth peaks every year: the first growth peak appears when the new shoots stop growing; The second peak appeared from September to 10. Under suitable conditions, pear roots can grow all year round without dormancy.
phenophase
Pear trees are widely distributed, so their phenological periods are very different. As far as flowering period is concerned, Huili and pear trees in Sichuan generally bloom in the first half of February, and Yanbian in Jilin blooms in mid-May. Yali pear bloomed in Changsha, Hunan Province in early March and in Beizhen, Liaoning Province in early May, with a difference of nearly two months. Pear trees cultivated in the same area have different phenological periods due to different species and varieties. From germination to flowering, Qiuzi pear was the earliest, Pak Lei pear was a little later, Shali pear was later than Pak Lei, and Xiyang pear was the latest, with a variation range of about 10 day. See Table 2.
Table 2 Requirements for Environmental Conditions
Different pear varieties have different requirements for environmental conditions, forming their own ecological distribution areas. ① temperature. Pear trees like temperature, so they need higher temperature during growth and lower temperature during dormancy. The suitable annual average temperature of pear trees is 4 ~ 12℃ for Qiuzi pear, 7 ~ 15℃ for Pak Lei and Xiyang pear, and 13 ~ 2 1℃ for Sha pear. When the soil temperature reaches above 0.5℃, the roots begin to move, and new roots grow at 6 ~ 7℃; when it exceeds 30℃ or drops below 0℃, the growth stops. When the temperature is above 5℃, pear buds begin to germinate, when the temperature is above 14℃, they can blossom, and when the temperature is above 14℃, the flowering is accelerated. The optimum temperature of flower bud differentiation and fruit development is about 20℃, and the optimum temperature range of photosynthesis is wide, and photosynthesis does not decrease much at 30℃. In the process of fruit ripening, the temperature difference between day and night is large, which is conducive to the improvement of quality. Different kinds and organs of pears have different cold tolerance. Qiuzi pear, which originated in northeast China, is extremely cold-resistant, and its wild species can tolerate -52℃ and its cultivated species can tolerate -30 ~-35℃. Pak Lei can withstand-23 ~-25℃; Sand pear and sand pear can tolerate about -20℃. The critical freezing temperatures of pear organs in Laiyang, Shandong Province are -5℃ in bud stage, -3.5℃ in inflorescence separation stage,-1.5 ~-2℃ in flowering stage and-1.5℃ in flowering stage. ② illumination. Pear tree is a high-gloss fruit tree. The annual sunshine demand is between 1600 ~ 1700 hours. The light compensation point of pear leaves is about 1 100 lux (lx), and the light saturation point is about 54,000 lux (lx). The light conditions in the canopy of pear trees account for 10 ~ 15% in the projection in the tree tray at noon on a sunny day, so it is suitable to distribute evenly. 3 moisture. During the growing period of pear trees, there is more water demand. The transpiration coefficient (grams of water required for a tree to produce 1 g dry matter) is 284 ~ 40 1, and the transpiration water per square meter of leaf area is about 40 grams. If it is lower than10g, it will cause injury. Qiuzi pear, Pak Lei pear and Xiyang pear have poor moisture tolerance, while Shali pear has strong moisture tolerance. In sandy loam, when the soil water content is 15 ~ 20%, it is suitable for root growth, and when it is reduced to 12%, the root growth is inhibited. Excessive soil moisture will lead to poor root growth. For fruits developed in rainy and humid climate, the stomatal cuticle of the peel is easy to break, the fruit point is generally enlarged, the peel becomes rough, and fruit rust is easy to appear. ④ Soil. Pear trees have strong adaptability to soil, and sandy loam with deep soil layer, loose soil, good air permeability and water retention and low groundwater level is the most suitable. Pear trees have wide adaptability to soil acidity and alkalinity, and can grow normally in the range of pH 5 ~ 8.5, and pH 5.8 ~ 7 is the most suitable. Pear trees also have strong salt and alkali tolerance. When the soil salt content is below 0.2%, it grows normally. When it reaches more than 0.3%, the root growth is damaged and the growth is obviously poor. Generally speaking, Du pear requires partial alkali, while Sha pear and Dou pear require partial acid.
Main types and varieties
The main cultivated varieties in China are Pak Lei and Qiuzi pear. ), pear (P. Pyrofilia (Burm. ) Nakai), Xinjiang pear (P.sinkiangensis Yü) and Western pear (P. Communis L.).
Pear varieties are extremely rich, with more than 7,000 varieties in the world and more than 3,500 in China. The main fine varieties are: ① Nanguo pear. It is a natural hybrid seedling. Originally from Anshan, Liaoning, it is mainly distributed in Haicheng, Anshan, Liaoyang and other places in Liaoning. The fruit is oblate and small, with an average weight of about 50g. The background color of the fruit surface is yellow-green, the sunny surface is flushed or orange-red, and it is pure yellow after maturity. The pulp is crisp, sweet and juicy, soft after ripening, easy to dissolve in the mouth, juicy, less stone cells, moderate sweet and sour, rich in aroma and excellent in quality. In the first half of September, the fruit is ripe, which is not resistant to storage and the plant has strong cold resistance. More resistant to scab. ② Yali pear. It is the most cultivated pear variety in China. Mainly distributed in Hebei, Shandong, Liaoning and other provinces. The fruit is obovate, and there is a duck-head bulge near the fruit stalk, so it is named Yali. The fruit is medium and large, with an average weight of 150 ~ 2 15g, and the largest fruit is 530g. The peel is yellow-green, thin, smooth and slightly waxy. The flesh is white, thin and crisp, sweet and juicy, with a slight fragrance; Small nucleus, few stone cells and good quality. Mature in the middle and late September, resistant to storage. It is a cold-resistant variety in Pak Lei, but not resistant to scab. 3 pears (thorn pears). The fruits produced in Laiyang and Qixia, Shandong Province are mostly oval, protruding from the top of calyx, nearly spindle-shaped, with an average single fruit weight of 130 ~ 250g, yellow-green or green fruit surface, large fruit point, yellow-brown and rough skin. The pulp is milky yellow, crisp and juicy, very sweet, slightly fragrant, with less stone cells and less sour taste. The fruit ripens in late September and is storable. There are many axillary buds, and the flower organs are poor in low temperature resistance, wind resistance, disease resistance and drug resistance. (4) Pak Lei in autumn. The main producing areas are western Liaoning and northern Hebei. The fruit is nearly spherical, medium-sized, with an average single fruit weight of 120 ~ 150g and a thick yellow peel. The pulp is white, juicy, sweet, with small stone cells and medium quality. The fruit ripens in late September and can be stored until May to June of the following year. Drought tolerance, suitable for mountain cultivation, not resistant to scab. Five crisp pears. Originally from Dangshan, Anhui. Jiangsu, northern Anhui and Henan Ningling are more cultivated, and the introduction and cultivation in northwest and north China are better. There are many strains. In production, most of them are white skin crisp. The fruit is nearly cylindrical and large, with an average weight of about 270 grams. The peel is smooth, yellow-green at harvest and yellow-white after storage. The pulp is white, slightly thick and crisp, sweet and juicy, with small stone and high quality. At the beginning of September, the fruit is mature and storable. Strong resistance, weak wind resistance, easy to drop fruit before picking. Six apples and pears. Mainly produced in Yanbian, Jilin, with Yanji County as the most concentrated cultivation area. Liaoning and Inner Mongolia are also cultivated, and the introduction and trial planting in the northwest have performed well. The fruit is oblate and large, with an average weight of about 250g and a maximum weight of 600g. It looks like an apple, hence its name. The peel is yellow-green, with bright red halo on the sunny side and yellow after storage. The flesh is white, crisp, juicy, sweet and sour, with small nucleus and few stone cells. The fruit of/kloc-0 is mature and storable from the end of September to the beginning of October, but the peel tends to turn black after being pressed. Cold resistance, low temperature of -30℃, weak resistance to scab, fruit eating disease and rot. ⑦ Korla pear. Originated in southern Xinjiang, Korla is the most famous producing area. The fruit is small, generally oval, with an average weight of 80 ~100g. The peel is thin and yellow, with faint orange halo on the sunny side, and the fruit point is small but not obvious. The flesh is yellow-white, tender, juicy, sweet, with large stone and high quality. The fruit ripens in early September and can be stored until April of the following year. Plants are drought-tolerant, more resistant to scab and not wind-resistant. 8 Jinchuan Sydney. Also known as drumstick pear. Originally from Jinchuan, Sichuan, it is widely cultivated in Sichuan, with a small amount of cultivation in Jiangxi and Yunnan. The fruit is obovate, large and shaped like a drumstick, with an average weight of about 350 grams. The flesh is white, crisp, sweet, juicy and slightly fragrant. Jinhua pear bred by this variety has good quality. Fruit10 ripens from late September to early June and can be stored until April to May of the following year. Like cold, cool and semi-dry climate, with strong adaptability and insect resistance. When planted in hot and humid areas, the yield and quality often decline. 9 golden pineapple. It was bred by Fruit Research Institute of China Academy of Agricultural Sciences on 1956 with apple pear× pear. The trial planting in Liaoning, Beijing, Hebei, Henan, Gansu and other places performed well. The fruit is nearly spherical and large, with an average weight of 230 ~ 280 grams. The peel is yellow-green with waxy luster, yellow after storage, and the fruit point is large and obvious. The flesh is white, crisp, juicy, sweet, slightly fragrant, with small stone cells. The fruit 10 ripens from late September to early October, and can be stored until May of the following year, especially after storage. Cold resistance and scab resistance. Attending the twentieth century pear. Originally from Japan. Jiangsu, Shanghai, Zhejiang and Beijing have a small amount of cultivation. The fruits are medium and large, mostly nearly round, with an average weight of about 150g. Yellow-green skin, white flesh, crisp meat, sweet and juicy taste, large nucleus and few stone cells. It ripens in Shanghai from late July to early August and is not resistant to storage. Cold resistance, wind resistance and disease resistance are weak. ⑾ Barry (Bartlett). Dalian, Liaoning, Yantai, Shandong and the old course of the Yellow River are widely planted. The fruit is ladle-shaped, larger, with an average weight of about 250 grams. The peel is yellow, the sunny side is red, and the pulp is milky white. When ripe, the meat is soft, soluble in the mouth, juicy, sweet and of high quality. The fruit of Yantai, Shandong Province ripens from the end of August to the beginning of September, and its cold resistance and disease resistance are weak.
There are many other excellent varieties, as shown in Table 3.
Key points of cultivation techniques
type
Grafting propagation is generally adopted. There are many kinds of rootstocks used for grafting, such as Li Du pear. ), Qiuzi pear, Li Dou pear. ) and pears. Li Du has deep roots, vigorous growth, drought resistance, waterlogging resistance and salt tolerance, and is widely used in pear areas in northern China. Qiuzi pear wild species has developed root system, cold resistance and rot resistance, and is an excellent rootstock suitable for pear trees in cold and dry areas in the north. Li Dou and Sha Li have developed roots, strong adaptability to soil, waterlogging resistance, acid resistance and clay resistance, and are the main rootstocks of pear trees in the Yangtze River valley and warm rain areas in the south of the Yangtze River. In addition to Li Dou and Li Duli as rootstocks, there are also quince. It is often used as a rootstock in dwarfing culture. Anger, Provence. Quince has the disadvantages of weak affinity and poor cold resistance for many pear varieties, so intermediate rootstocks are generally used for grafting. At present, China pear trees lack dwarf rootstocks for grafting.
get a first reign title after the founding of a dynasty
Pear trees have wide adaptability, and gardens can be built on flat land, sloping land and sandy wasteland. But sandy loam with deep soil layer, fertile soil and good drainage is the most suitable. Orchard planning should be done well before the garden is built, and the sloping land should be planted at the same height. After planting, soil and water conservation projects such as terraces and furrows should be built to prevent soil erosion. Windbreak forest should be provided for garden construction in windy and sandy areas, and drainage and salt washing should be done well before garden construction in saline-alkali land with high groundwater level.
Advocate moderate close planting. Generally, the row spacing of pear orchards is not less than 4 ~ 5 meters, and the plant spacing is not less than 2 ~ 3 meters. Mountain, thin land and dwarf rootstock seedlings can be slightly dense; Flat land and fertile land should be properly thinned. Most pears are not self-flowering. When the garden is built, pollinated varieties should be configured (see Table 4). The ratio of pollinated varieties to main cultivated varieties is generally 1: 3 ~ 5.
When planting, choose strong seedlings, dig big holes, apply sufficient fertilizer, cover the soil after irrigation, and the dry height is generally 60 ~ 90 cm.
Plastic trimming
According to the characteristics of pear tree, such as strong dryness, obvious bedding, upright growth of young branches, small opening angle, strong germination, weak ability to form branches, great difference in growth potential of individual branches, and stopping the growth of early branches. Generally, it is better to adopt the evacuation layered shape or the three-bracket shape (see tree).
The meat is crisp, juicy and sweet, but slightly sour. It weighs 2000 grams and is broadly obovate. It is dark brown and cannot be stored and transported in Wuhan, Hubei Province in the middle and late September. Crispy and juicy, looking for 140g, oblate. Yellow-green, Hangzhou, Zhejiang, more resistant to storage and transportation. The meat is crisp, juicy and sweet, weighing 187 ~ 200g, oval and yellowish brown. In August, Sydney, Guanyang, Guangxi, is more resistant to storage and transportation. Yellow-green in late August, Yunnan Chenggong and Jinning meat is very fine, juicy, crisp and sweet. 1 150g, short fenugreek. Yellow-green in late July, Henan Panbaozhu pear is tender, juicy, sweet and fragrant, weighing 280g, and yellow in late September, Hanyuan, Sichuan. Yellow can be stored in Gansu Longzhong from the end of September to the beginning of 10 until the following year. The meat is fine and crisp, and the juice is mostly medium and large. Weight 147g9. Petiole perfume can be kept until May of the following year. The meat on 6 slices is crisp, tender and juicy, sweet and sour, weighing L56 ~ 240 g, oval and yellow. ! In mid-September, Zhang Like in northern Hebei can be stored until March-April of the following year. The meat is crisp, juicy, sweet, small, l00g columnar and yellow-green. In the middle and late September, Zhang Li in northern Hebei can be stored until March-April of the following year. The meat is soft, juicy, thick and sweet, weighing 65g, similar to the shape of fenugreek, and yellow-green. It can be stored in northern Liaoning province until March-April of the following year. Yellow-green color from late September to late June 10, Liaoxi Yali pear is not resistant to storage. Its upper pulp is soft, juicy and sweet, and the stone cells are mostly medium and large. It is not only oval, but also dark green. In mid-September, the upper pulp of 1 stored in Beijing was soft, juicy and sweet.
Table 3 Three Ji Hong eye pears. Cherry Bali is three auspicious days late. Imamura Autumn, Taibai and Apple Pear are pears of the 20th century. Xixi Sydney, Jinchuan Xiaoliao Pear, Li Ji Fragrant Pear and Crispy Pear Array Erli Fragrant Pear. Dashui fragrant pear, crisp pear, Jinfeng crisp pear, snow pear.
Table 4 Young trees should be lightly cut and more branches should be left. In addition to properly cutting off the extension branches, main branches and side branches of the central trunk, it is generally appropriate to slow down the cutting. For varieties with weak branching ability and easy flowering, long branches should be less sparse and cut more; For varieties with strong branches and difficult flowering, the branches can be thinned appropriately and combined with slow release. In the growing season, for the main branches and auxiliary branches with small opening angles, the method of "pulling, supporting and topping" is used to open the angles, so as to alleviate their growth potential, expand the crown and promote early flowering and early fruiting. Attention should be paid to the balance of tree potential, the cultivation of fruiting branches and the control and adjustment of auxiliary branches after fruiting. In the full fruit period, trees should adjust the relationship between fruit bearing and growth, and cut the 1 annual branches moderately to reduce the slow-release branches; Retract and sparse over-dense auxiliary branches; Pay attention to keep the branch angle of the main branch and the side branch, and replace the drooping part at the top; Renew the rejuvenation culture fruiting branches, and adjust the proportion of all branches, the number of branches and the retention of flower buds. According to the experience of high-yield pear orchards in Shandong, Hebei, Liaoning and other places, the number of branches per hectare of pear trees is about 654.38+0.2 million ~ 654.38+0.35 million, and the most suitable amount of flower buds after pruning is 30 ~ 40% of the total number of branches. New year's trees should cut off more flower buds and keep more leaf buds; Young trees tend to shrink back to the weak flowerless group and retain more buds. Old trees should pay attention to renewing backbone branches, and use long branches to cultivate backbone branches and new fruiting branches. Close planting should also pay attention to controlling tree height and limiting crown width. After fruiting, the number of main branches and branchlets of the whole tree should be adjusted to keep the crown well ventilated and transparent, and improve the fruit quality and yield.
soil management
In pear orchards where the soil has not been improved before planting, it is beneficial to the growth and fruiting of pear trees to deepen and ripen the soil during the young tree period. Generally, reaming and deep turning in different years can be adopted. Deep tillage combined with application of organic fertilizer can increase the organic matter content in deep soil. In mountainous areas, beaches and pear orchards with shallow soil layers, soil should be pressed to thicken the soil layer. Plants can be cleared or covered; Leguminosae, short dry crops or green manure crops should be intercropped between rows, or planted with grass or covered. Clear tillage orchards need intertillage weeding and deep ploughing every autumn to loosen the soil.
Pear trees need to be fertilized every year to ensure the robust growth, flowering and fruiting of the trees. In order to promote the growth of barren young trees, nitrogen fertilizer is mainly applied; After the results, fertilizers such as nitrogen, phosphorus and potassium need to be applied together. The base fertilizer is mainly organic fertilizer, which is applied once a year or once every other year. The base fertilizer should be applied before the fruit leaves fall after harvest, and the topdressing should be 2 ~ 3 times a year. It is the first time that before germination, nitrogen fertilizer is mainly used to promote the growth of branches and leaves and the development of flower organs, and improve the quality and fruit setting rate of flowers. The second time, in the slow growth period of new shoots, phosphorus and potassium fertilizer were mainly applied, combined with topdressing nitrogen fertilizer. Plants with more fruits can be topdressing again. This top dressing is mainly nitrogen and potassium, which promotes fruit hypertrophy and flower bud differentiation. According to the change of leaf color, foliar fertilizer was sprayed in stages during the growth period, nitrogen fertilizer was sprayed in the early stage, and nitrogen, phosphorus and potassium fertilizer were applied in the later stage. After the fruit is harvested, it can also be sprayed with 1 ~ 2 times to strengthen the accumulation of photosynthetic products in the later stage.
The young unfruitful trees should be applied with pure nitrogen of 75 ~ 150kg per hectare, and the fruiting trees can be calculated according to the fruit yield, that is, the pure nitrogen should be applied with 0.5kg per 100kg pear. The annual application ratio of NPK is 1: 0.4 ~ 0.5: 0.8 ~ 1. Whether the amount of fertilization is appropriate can also be judged according to the leaf content. According to relevant data, the suitable contents of three elements in leaves of high-yield pear trees are: nitrogen 2-2.5%, phosphorus 0. 12-0. 16%, potassium 241205-10.8%. If the contents of three elements in leaves are lower or higher than the above standards, fertilization should be applied.
Pear needs a lot of water, and the irrigation period and times depend on climatic conditions and soil drought. Irrigation is usually 3 ~ 4 times a year. Irrigation in spring germination stage is beneficial to germination, leaf spreading, flowering, fruit setting and the growth of new shoots and leaves. After flowering, it is necessary to irrigate again at the critical period to promote the growth of new shoots, fruit hypertrophy and flower bud differentiation. Irrigation after harvest can improve the photosynthetic function of leaves, which is beneficial to nutrient accumulation, branch and bud enrichment and root growth. Irrigation before soil freezing in pear areas in northern China can improve the frost resistance and drought resistance of plants in winter. Irrigation amount should be appropriate. Generally, water should penetrate into the main distribution layer of root system, that is, the soil water content should reach 70 ~ 80% of the maximum water holding capacity in the field. Pear orchards with low terrain, high groundwater level and easy waterlogging should also pay attention to drainage and waterlogging prevention.
artificial insemination
When there are few pollinated trees, pollinated trees and main varieties bloom in the same year, or there are bad weather such as rain and strong wind in the flowering period, artificial pollination or bee release in the flowering period can improve the fruit setting rate and yield.
blossom and fruit thinning
For pear trees with large flowers and many fruits, it is necessary to sparse flowers and fruits, control the flowers and fruits of the whole tree, reduce nutrient consumption, improve fruit quality and overcome the years. Thinning flowers and fruits can be done manually or by drugs. Artificial flower thinning is carried out from inflorescence elongation to flowering. The artificial fruit thinning period is generally carried out after physiological fruit dropping, and the amount of fruit left varies with varieties, tree potential, branch group strength and management conditions. Generally, fruits can be kept according to the ratio of leaves to fruits and the ratio of branches to fruits. Leave one fruit for big fruit every 3-4 branches or 15-30 leaves, and one fruit for small fruit every 2-3 branches or10-5 leaves. Flower-thinning and fruit-thinning agents can be sprayed with NAA, carbaryl and other flower-thinning and fruit-thinning agents at the initial flowering stage, full flowering stage and after flowering.
Eliminate pests and diseases
The main diseases are pear scab, pear rust, ring rot and black spot, among which the scab and ring rot are more common and serious. The main control methods are cleaning leaves, cutting off diseased branches, diseased leaves and diseased fruits, and spraying drugs in time to protect them. The main pests are pear moth, peach moth, pear moth, pear star caterpillar, hawthorn spider mite, pear aphid and so on. In the prevention and control, it is necessary to predict the insect situation and prevent and control it in time according to the occurrence period.
economic value
The nutritional value of pears is very high, except for more than 80% water, the sugar content is mostly above 8%, and the highest can reach about 20%. Every 100g of fresh fruit contains protein 0. 1g, fat 0. 1g, carbohydrate 12g, calcium 5mg, phosphorus 6mg, iron 0.2mg, carotene 0.0 1mg and thiamine 0.0/kloc. In addition to being eaten raw, pears can also be made into dried pears, preserved pears, pear sauce, pear juice, pear sauce, pear cakes, canned pears, wine making and vinegar making. Pear fruit has the medical functions of helping digestion, moistening lung and cooling heart, eliminating phlegm, relieving cough and fever, relieving sores, relieving alcoholism and so on. Pear skin, pear branches and pear wood can all be used as medicine. Pear trees are hard, upright and excellent in texture, and are excellent raw materials for furniture and textile industry.