Detailed explanation of An pear cultivation techniques, key points of scientific planting and management
An pear is one of the important varieties of the Ussurian pear system, mainly distributed in the Yanshan mountain area of northeastern Hebei Province and western Liaoning Province. An pear is loved by people for its unique flavor, golden color, low price and extremely strong storability; it is also widely cultivated in the Yanshan mountain area for its strong resistance and adaptability.
1. Variety characteristics
The fruit of An pear is spherical or oblate, containing soluble solids 12.9%-16.2%, organic acids 0.9-1.43%, vitamin C 8.2-10.7mg/100g, with a sweet-and-sour fresh fragrance. At harvest, the flesh firmness reaches 17.5kg/sq cm, and after ripening it softens and melts in the mouth. Under ordinary cellar storage conditions, the above transformation process takes 5-7 months, giving it a storability that ordinary pear varieties cannot match.
2. Soil, fertilizer and water management
Soil, fertilizer and water management is closely related to the safe overwintering of young trees. Generally, during the young tree stage (4-6 years old), fertilization and irrigation must be strictly carried out according to the principle of promoting early and controlling later. That is, before July, irrigate according to the soil moisture condition of the pear orchard. Base fertilizer should be applied as much as possible before the winter irrigation of the previous year; if applied in early spring, it must be completed between the end of March and early April. Nitrogen fertilizer topdressing during the young tree stage must be completed before May, and nitrogen fertilizer topdressing is strictly prohibited in the late growth period. After young trees bear a large amount of fruit, the above fertilizer and water management method can be changed, that is, appropriately increasing the number of irrigations after July and applying a small amount of nitrogen fertilizer as topdressing. Because An pear young trees grow vigorously, in densely planted orchards the inter-row space is generally not intercropped, and clean cultivation is maintained. In sparsely planted orchards, during the young tree stage, spring @#@245@#@ and spring-sown summer-harvested vegetables can be interplanted; it is absolutely forbidden to intercrop Chinese cabbage, green radish or late cabbage that require large amounts of fertilizer and water after autumn. In mature sparsely planted orchards, crops are generally no longer interplanted.
(1) Deep plowing and hole expansion, building up soil fertility
Deep plowing and covering with soil: carry out deep plowing according to the range of the tree canopy projection, keep the outer part deeper, and avoid damaging large roots as much as possible; dig out gravel, and when backfilling, mix the weeds, leaves, or grass turf soil with grass clods around the ditch with the topsoil and fill it level; for pear trees with exposed roots or growing on gentle slopes, build terraces along the contour line, raise the field ridges, and carry out soil replacement covering. Whether by deep plowing or soil replacement covering, the living soil layer should be no less than 60-90cm. At the same time, we also experimentally applied a high-energy drought-resistant water-retaining agent (product of China Tangshan Boya Science and Technology Industry Development Co., Ltd.) and achieved good results. The application method is: trench application or pit application. Before the rainy season, within the tree disk, dig pits (trenches) 30cm deep, the size of which can be determined by the size of the tree canopy, and mix the soil from the bottom 10-15cm of the trench with the water-retaining agent and backfill. The application amount is calculated according to the vertical projection area of the tree canopy, generally 10-20g/sq m, with a cost of 2-4 yuan per tree, suitable for orchards in deep mountain areas without irrigation conditions.
(2) Scientific fertilization to keep the tree body vigorous.
Increase the application of organic fertilizer and phosphorus and potassium fertilizers, and control the amount of nitrogen fertilizer. Application standard for organic fertilizer (base fertilizer): for every 1kg of fruit produced, apply at least 1kg of fertilizer. For example, for a pear orchard with a yield of 2500kg per mu, apply more than 2500kg of high-quality barnyard manure per mu; corn stalks, green manure and fallen leaves, etc., can be applied to the pear orchard together with the base fertilizer. On the basis of applying organic fertilizer, the average annual application of pure nitrogen per ton of pear fruit should not exceed 4kg as the appropriate amount, and nitrogen fertilizer topdressing should be stopped 6 weeks before fruit harvest. After July, foliar spraying of 300-fold potassium dihydrogen phosphate can be carried out 2 times. The application amounts of nitrogen, phosphorus and potassium are generally appropriate at a ratio of 1:0.5-1:1.
3. Training and pruning
Sparsely planted orchards generally adopt the central-leader delayed-open form for training. Keep 6-7 main branches in 3 tiers: 3 main branches in the first tier, 2 in the second tier, and 1 in the third tier. Tree height is controlled at 3.5-4m. On the first-tier main branches, appropriately keep 3-4 lateral branches, select and keep 2 lateral branches on the second tier, and keep no lateral branches on the third tier. Generally, 5-6 years are needed to complete the training task. An pear young tree branches are brittle and upright; large tree branches tend to produce drooping, slender and weak branches, so young trees mainly focus on opening the branch angles. Long branches growing horizontally or obliquely and left unpruned readily form flower buds, but after fruiting they should be headed back in time. For pruning of fruiting trees, the main purpose is to control tree height, head back fruiting branch groups that have been left unpruned for years and have weakened, so as to renew and rejuvenate them, and adjust the ratio of vegetative branches to fruiting branches. For excessively tall trees, the central leader should be headed back and the top opened at an appropriate position, so that the tree body is well ventilated and light penetrates, the tiers are opened up, and the density of large and medium-sized scaffold branches is adjusted so that they are distributed sparsely. Through pruning, the tree height is controlled at 3.5-4m, and during the growing season the area of light spots under the tree is maintained at more than 15% of the tree canopy projection area.
4. Artificial pollination
Because An pear blooms early, it often flowers early, sets few fruits, and has low yield and poor quality. Through years of cultivation experiments and research, we selected from many treatments the top-grafting of An pear with Yali pear (in our area An pear and Yali pear bloom synchronously), spraying gibberellin at full bloom, and artificial supplementary pollination, which are effective technical measures to increase yield and quality. Among them, artificial pollination has the best effect: the flower fruit-setting rate is increased by 2.25 times compared with natural pollination, reaching 58.51%, and the yield is increased by 1.95 times. Moreover, the fruit quality is markedly improved, with thin skin, fine flesh, abundant juice and good taste.
Yali pear and Xuehua pear have strong pollination compatibility with An pear and are relatively ideal pollinating varieties, but mastering the pollination period is the key to increasing the fruit-setting rate. Because the most suitable time for the An pear stigma to receive pollen is the day of flowering and the second day, and then it gradually weakens. Pollination must be completed within 3 days of flowering to achieve good results; if pollination is completed 4-6 days after flowering, the fruit-setting rate drops to 28.44%. The pollination method is: after sifting the cracked pollen, add 2-5 parts of fine talcum powder to each part of fine pollen and mix thoroughly; put the prepared pollen into a small bottle, first dip a little with a brush or paper stick, and gently dab it on the stigma. Generally, pollinate one cluster at intervals of about 25cm; each dip can pollinate 3-5 clusters, and dabbing 2 flowers per cluster is sufficient. In addition, a sand cloth bag can also be used to shake-pollinate, and the effect is also relatively good, but the amount of pollen used is larger. Generally, pollination within 3 days to 1 week after flowering gives the best effect.
In addition, An pear blooms early, and late frost damage often occurs during the flowering period. In our view, the most effective method to rescue frost damage is the smoke method, which can effectively reduce and prevent frost damage. Fallen leaves, straw and weeds can all become smoke materials; in addition to the above materials, smoke agents are the best material; smoke agents are made by mixing sawdust, asphalt, diesel oil and ammonium nitrate. After the sawdust is dried, mix it evenly with ammonium nitrate, then add melted asphalt and diesel oil, slowly pour in while stirring evenly, pack 5kg per package, and wrap it well for later use. In early spring, when the temperature drops to 0.5°C, begin to light the smoke agent, 2-3 packages per mu. The frost prevention effect is relatively good.
5. Strengthen pest and disease control
During the growing season, An pear trees experience high temperature and abundant rain, and pests and diseases occur easily, and with the increase of tree age, there is a trend of gradually intensifying pest and disease damage. For pear scab, it is advisable to spray 3 degrees Beaumé lime sulfur mixture at the early bud stage; after rain during the flowering period, spray 25% carbendazim wettable powder 400-fold solution, which does not affect the fruit-setting rate; thereafter, at intervals of 15-20 days, alternately spray 1:2.5:200 Bordeaux mixture, 40% carbendazim suspension concentrate 500-fold solution, or 80% thiram wettable powder 1000-fold solution until the end of June, and spray 1 protective fungicide in early September. The above measures can control the diseased leaf rate and diseased fruit rate of pear scab below 5%. Peach fruit borer and codling moth have often broken out and caused damage in recent years. The control method is: after the overwintering larvae pupate and before the adults emerge from the soil (mid-May and early June), use 50% phoxim emulsifiable concentrate 0.8-1kg, add water 50-90 times, and spray evenly under the tree canopy (on the ground surface). During the hatching period of the first-generation eggs, spray 20% cypermethrin 3000-3500-fold solution, reducing the damaged fruit rate to below 1%. Pear psylla has caused severe damage in some pear orchards in recent years. According to its strong pesticide resistance, pesticides should be changed frequently. Spray cyhalothrin, cypermethrin and other pesticides before and after flowering, which can achieve good control effects.