Detailed Explanation of Blueberry Planting Techniques and Cultivation Management Key Points
Blueberry is a berry shrub of the genus Vaccinium in the family Ericaceae. The unique substances in its fruit, such as blueberry anthocyanins, have effects such as improving eyesight, anti-aging and cancer prevention. It is known as the "functional health berry of the 21st century" and the "queen of fruits", and has been listed by the International Food and Agriculture Organization as one of the five major health foods for humans. In recent years it has become popular in Europe, America and Japan. Because blueberry has unique nutritional and health functions, the demand on the international market is extremely large, and the price is high, with products in short supply.
Variety Characteristics of Blueberry
The blueberry fruit is similar in size to a cherry, blue to bright blue in color, sweet and sour in flavor with a special aroma, and has an excellent taste. Blueberry seeds are extremely small and almost imperceptible in the mouth. There are no inedible parts such as the stalk and seed found in cherries, making it very convenient to eat.
Blueberry is the collective name for plants of the genus Vaccinium in the family Ericaceae. It is called blueberry because its fruit is blue. It is mainly distributed in North America and Europe. The tree height is 1-2 m. It prefers acidic soil and is not tolerant of drought. At present, there are nearly 200+ cultivated varieties worldwide worth promoting, and they can be divided according to different climatic characteristics into:
1. Lowbush blueberry and northern highbush blueberry, suitable for the colder regions of the north;
2. Southern highbush blueberry, suitable for the warm temperate regions of the south;
3. Rabbiteye blueberry, suitable for the southern regions, etc.
Among them, northern highbush blueberry is better than the other two types in both flavor and anthocyanin content, and has the largest international market demand.
Blueberry is a perennial deciduous or evergreen shrub. The fruit is blue and nearly round, with a single fruit weight of 0.5-2.5 grams and extremely small seeds. The flesh is delicate, moderately sweet and sour, and aromatic. It can be eaten fresh or processed into jam, juice, fruit wine, etc. Blueberry cultivation first began in the United States. Almost all of China's original blueberry varieties are wild and not suitable for cultivation. More than 20 years ago, China began introducing excellent foreign varieties, and to date more than 20 varieties have been introduced, but large-scale production capacity has not yet been formed.
Orchard Site Construction for Blueberry Planting
1. Orchard Site Selection
Blueberry has a relatively wide cultivation range, and suitable varieties can be selected according to the local climate, but northern regions that are dry with little snow and prone to frost damage are not suitable for development. The selected orchard site should have a small slope, not exceeding 10 degrees; soil pH 4.0-5.5, with the most suitable range being 4.3-4.8; soil organic matter content not less than 5%; and soil that is loose, well aerated, moist but not waterlogged.
2. Orchard Site Preparation
After the orchard site is selected, deep plowing combined with green manure incorporation should be carried out one year before planting, with a depth of 20-25 cm being appropriate. After deep plowing and soil ripening, the land should be leveled. Before planting, soil that does not fully meet the requirements should also be improved to facilitate blueberry growth.
3. Planting
Blueberry can be planted in both spring and autumn, with autumn planting giving a higher survival rate, while spring planting should be done as early as possible. For plant and row spacing, rabbiteye blueberry commonly uses 2 m × 2 m or 1.5 m × 3 m, highbush blueberry uses 1.2 m × 2 m, and lowbush blueberry uses 0.5-1 m × 1 m. Rabbiteye blueberry is self-unfruitful, so it is best to configure highbush blueberry as a pollinator variety. Highbush and lowbush blueberries have a relatively high self-fruiting rate, but configuring pollinator trees can improve fruit quality and yield. The ratio of main cultivars to pollinator varieties is 1:1 or 1:2.
Soil, Fertilizer and Water Management for Blueberry Planting
1. Soil Management
The blueberry root system is relatively shallow and fine, without root hairs, so the soil is required to be loose and well aerated.
① Clean cultivation. Clean cultivation can be carried out from early spring to August, but after autumn sets in, clean cultivation is unfavorable for overwintering. Highbush blueberry cultivated on sandy loam commonly uses clean cultivation. The depth of clean cultivation should be 5-10 cm; too deep easily damages the root system.
② Sod culture. Sod is grown between rows, while herbicides are used within rows. Compared with clean cultivation, sod culture is similarly beneficial for increasing yield and also has the advantages of maintaining soil moisture and facilitating mechanical operations.
③ Soil mulching. Soil mulching is widely applied in blueberry production. It has multiple functions such as increasing soil organic matter, improving soil structure, regulating and maintaining soil moisture, lowering soil pH, and controlling weeds. Mulching lowbush blueberry with 5-10 cm of sawdust can increase yield by 30% within 3 years and increase single fruit weight by 50%. Leaves, rice straw and other crop straw can also be used, but the effect is not as good as sawdust.
④ Weeding. In blueberry orchard management, weeding is a very important part. When done well, it can increase yield by more than 1 times. In blueberry production, chemical herbicides are widely used. This is because manual weeding is costly and easily damages the root system. Especially in lowbush blueberry cultivation, because the rhizomes spread and run, after a few years the entire orchard becomes connected as one patch, making manual weeding impossible. Commonly used herbicides in blueberry orchards include diuron, simazine, chlorbromuron, 2,6-dichlorobenzene, glyphosate, paraquat, etc.
2. Fertilization
① Types of fertilizer. Applying nitrogen-phosphorus-potassium compound fertilizer is more effective than applying single-element fertilizers; the ratio of nitrogen, phosphorus and potassium fertilizers should preferably be 1:1:1; it is best to apply ammonium nitrogen fertilizers such as ammonium sulfate, and nitrate nitrogen fertilizers should not be applied; blueberry is sensitive to chlorine, so chlorine-containing fertilizers such as ammonium chloride and potassium chloride should not be selected.
② Fertilization method and timing. Highbush and rabbiteye blueberries can use the furrow application method, with a depth of 10-15 cm being appropriate; lowbush blueberry, after the orchard is established and connected as one patch, is mainly topdressed by broadcasting. Fertilization is carried out before budding in early spring, and can also be applied once more during the fruit ripening stage.
③ Fertilization amount. Excessive fertilization can very easily damage the blueberry tree, or even cause the entire plant to die. Therefore, determining the fertilization amount must be done very cautiously, and must be based on soil fertility and tree nutritional status.
3. Irrigation
The blueberry root system is shallow and prefers moisture, so timely irrigation is very necessary. Blueberry irrigation requires attention to water source and water quality. Deep well water generally has a relatively high pH and high sodium and calcium content, and long-term use will affect blueberry growth and yield. Sulfuric acid can be used during irrigation to adjust the pH to about 5 before irrigating, but acidic water should be applied once after about every 3 irrigations.
Pruning Techniques for Blueberry Planting
1. Pruning of Highbush Blueberry
① Pruning during the young tree stage. During this period, the main task is removing flower buds, with the purpose of expanding the canopy, increasing the number of branches, and promoting root development. In the second and third spring after planting, weak and small branches should be thinned out. In the third and fourth years, the main focus is still expanding the canopy, but a moderate amount of fruiting is allowed. Generally, in the third year, the yield per plant should be controlled below 1 kg, with fruiting mainly on strong branches.
② Pruning of mature trees. At this time, pruning is mainly to control tree height and improve light conditions, with thinning as the main method, removing overly dense branches, thin and weak branches, diseased and pest-infested branches, and root suckers. For varieties with a more spreading root habit, when thinning branches, remove the weak and retain the strong; for upright varieties, remove the central leader, open a "skylight", and retain medium branches. The best fruiting age for large branches is 5-6 years old; beyond that, they should be promptly renewed by heading back. For weak and small branches, remove the flower buds to make them grow stronger. Adult trees have a large number of flowers, so part of the flower buds should be pruned off. Generally, each strong branch retains 2-3 flower buds.
③ Renewal of old trees. About 25 years after planting, the aboveground part of the tree has aged and the whole tree needs renewal, that is, all the aboveground part is sawed off close to the ground, and new shoots regenerate from the base.
2. Pruning of Lowbush Blueberry
① Fire pruning. That is, during the dormant period, the entire aboveground part is burned off, new shoots regenerate, flower buds form in the same year, and flowering and fruiting occur in the second year. Thereafter, fire pruning is carried out once every 2 years, always maintaining fruiting on strong branches.
② Stubble pruning. Before budding in early spring, the aboveground part is cut flat from the base of the plant and all sawed off. The sawed-off branches are retained in the orchard, where they can serve to mulch the soil and increase organic matter.
Harvesting of Blueberry
Lowbush blueberry fruit ripens relatively uniformly, and early-ripening fruit does not easily drop, so it can be harvested all at once after all the fruit has ripened. After harvesting, remove dead branches, fallen leaves, stones and other debris, and place the fruit into containers. Highbush blueberry fruit does not ripen uniformly, and harvesting generally lasts 20-30 days, usually once every week. For fresh consumption, the fruit should be picked by hand; for processing, mechanical harvesting can be used.
How to plant blueberry? Key points of greenhouse blueberry planting techniques
In recent years, with the development of protected agriculture, greenhouse planting techniques have been widely applied to blueberry cultivation. Using greenhouse techniques to grow blueberries can improve the regional adaptability of blueberry cultivation, increase yield, and enhance the commercial value of blueberry fruit. So, how to plant blueberry? The key points of greenhouse blueberry planting techniques are introduced below.
Image: Blueberry planting
I. Construction of solar greenhouse
1. Site selection of the greenhouse:The solar greenhouse should be built in a location with flat terrain, good light, high soil organic matter content, convenient drainage and irrigation, and no pollution of water, soil or air. When selecting the planting plot, the soil pH and organic matter content should be understood or measured. If it is hilly land, try to choose the middle and lower parts of sunny slopes; the slope should not exceed 15°, and when greater than 15°, terraces with a minimum width of 8 m should be built.
2. Specifications and standards of the greenhouse:The greenhouse span is generally about 8-10 m, the wall thickness is 1 m, the ridge height is 4 m, and the rear wall height is 3 m. On the rear wall at a height of 1.5 m from the ground, a 60 cm × 60 cm ventilation opening is set horizontally every 4 m. The length of the greenhouse is unlimited; the rear wall of the greenhouse may be either earth-mounded or brick-built; there should be a certain spacing between greenhouses, not less than 1.8 times the greenhouse height, with the principle of not blocking light. Films can be of two types: PE drip-free plastic film with polyethylene as the main raw material and PVC drip-free plastic film with polyvinyl chloride as the main raw material; the temperature more suitable for blueberry growth inside the greenhouse is 20-25℃, with a maximum not exceeding 30℃ and a minimum not lower than 12℃.
Image: Blueberry planting
II. Soil conditions and soil improvement for greenhouse blueberry
Soil pH, organic matter content, water-holding capacity, air permeability, drainage and other conditions have a major impact on blueberry growth and are important prerequisites for whether blueberry planting can succeed.
1. Soil acidity and alkalinity:Blueberry prefers acidic soil. Most blueberries can grow normally in acidic sandy soil with a pH of 4.3-5.3, but different blueberry varieties have different required soil pH ranges. The suitable soil pH for highbush is 4.3-4.8, with 4.5 being the best; its lower pH limit is 3.8, and below 3.8 it causes damage to plant growth. The selected soil pH should be below 7.0, with 4.0-6.0 being the most suitable.
2. Soil organic matter content:Blueberry is suitable for growing in soil environments with an organic matter content of 3%-15%. Highbush blueberry especially needs soil with high organic matter content and must grow healthily in soil with an organic matter content above 3%.
Image: Blueberry planting
3. Soil aeration and water retention:The effective soil layer for blueberry cultivation should generally be maintained at about 50 cm. Ensuring soil aeration and water retention is crucial in blueberry cultivation, especially for highbush blueberry, which requires better aeration and water retention. For general soil, a three-phase distribution of 45%-50% solid phase and 20%-30% each for gas and liquid phases is relatively ideal, but for blueberry cultivation land, a combined value of 55%-60% for gas and liquid phases is most ideal. In order to achieve a relatively reasonable state of the three soil phases, deep plowing of 30-40 cm can be carried out, and then according to soil conditions, appropriately add decomposed moss, sawdust, cow manure, etc. and mix them into the soil. After that, when planting seedlings, build ridges 30 cm high, which can basically meet the growth requirements of blueberry.
4. Methods for adjusting soil acidity and alkalinity:The main problem with soil in most areas of China is that the pH is too high. Greenhouse cultivation can prepare organic soil suitable for blueberry growth before planting, but it is still difficult to fully meet the soil pH requirements of the variety, so the soil acidity and alkalinity must be adjusted before planting. At present, the relatively common soil adjustment method used domestically and abroad is applying sulfur to adjust soil pH. The main characteristic of sulfur in adjusting soil pH is that the effect is lasting and stable. After sulfur is applied to the soil, it needs 30-50 d to decompose before it can play a role in adjusting soil pH. The target for soil pH adjustment should be set at 4.5. If the expected target is not reached after adjustment, a second adjustment can be carried out by spraying 90% water-soluble sulfur. Under sandy soil conditions, for every 1 percentage point decrease, 15 g/m2 of water-soluble sulfur can be applied as the standard; for other soil types, the amount is 2 times that for sandy soil. However, the amount of water-soluble sulfur applied each time should not exceed 178 kg/hm2. If it must be applied in excess, it should be applied in 2 split applications in spring and autumn.
Image: Blueberry planting
III. Planting density and variety combination for greenhouse blueberry
1. Planting density:In open-field cultivation, highbush blueberry generally uses a plant and row spacing of 1.0 m × 2.0 m; forced cultivation using a greenhouse generally requires a planting density slightly higher than that in the open field, and a plant and row spacing of 0.5 m × 1.5 m is relatively suitable.
2. Land preparation:The standard size of planting holes for general open-field planting is 1.0 m × 1.0 m × 0.5 m. After the planting hole is dug, mix the removed soil with crushed pine bark and peat or humus soil from under pine forests, mix evenly, and backfill it into the hole. The backfilled soil should be 20-30 cm above the ground. If the soil acidity is insufficient, an appropriate amount of sulfur powder can be mixed in. Greenhouse cultivation can refer to the land preparation methods of open-field cultivation, but the depth and degree of land preparation must be higher than in open-field cultivation. Generally, full land preparation is best, using 50% garden soil and adding 50% peat, leaf mold, etc., to increase soil organic matter content and aeration. After land preparation, make beds 20-30 cm high, and the seedlings can be planted directly at planting time.
3. Variety configuration and planting time:Highbush blueberry can set fruit by self-pollination, but combining several varieties can significantly increase the fruit-setting rate. Therefore, when carrying out forced greenhouse cultivation of blueberry, the selected highbush blueberries should best be configured with more than two varieties for mutual pollination, in order to improve yield and quality. The ratio of main cultivars to pollinator trees is generally 2-3:1. The planting depth for 1-year-old seedlings is 15-20 cm. For every 1 a the seedling grows, the general planting depth should increase by 5 cm, and soil should be covered and pressed firmly. If potted seedlings are used, they can be planted all year round.
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IV. Production management techniques for greenhouse blueberry
1. Fertilization:Blueberry has a very low fertilizer requirement. When soil acidity is sufficient, generally only a small amount of N fertilizer needs to be applied. Excessive fertilization often leads to fertilizer overdose and harms the tree, affecting yield. Nitrate N is prohibited; urea is better. When applying K fertilizer, never apply KCL; K2SO4, etc. can be used. In production, organic fertilizer and farmyard manure such as pig and cow manure should be applied as much as possible. Green manure such as white clover can also be sown. The fertilization method is generally furrow application, which can effectively reduce fertilizer and water loss. When applying chemical fertilizer, the furrow width is 20-25 cm and the furrow depth is 10-15 cm; when applying farmyard manure or green manure incorporation in autumn and winter, the furrow width is 30-35 cm and the furrow depth is 35-40 cm; green manure is buried into the soil by turning and incorporating. Fertilization timing is generally divided into 3 applications: at budding, at fruit ripening, and after harvest.
2. Irrigation:The blueberry root system is shallow and prefers moisture, so timely irrigation is very necessary. Irrigation requires attention to water source and water quality. Deep well water generally has a relatively high pH and high sodium and calcium content, and long-term use will affect blueberry growth and yield. Sulfuric acid can be used during irrigation to adjust the pH to about 4.5 before irrigating, but acidic water should be applied once after every 3 irrigations.
Image: Blueberry planting
3. Temperature control:The key to forced cultivation is to break the flower bud differentiation period and dormancy period of blueberry. The temperature more suitable for blueberry growth inside the greenhouse is 20-25℃, with a maximum not exceeding 30℃ and a minimum not lower than 12℃. The chilling requirement of highbush blueberry must accumulate for 800-**** h under low-temperature conditions of 0-7.2℃. When the low-temperature requirement is insufficient, it causes poor budbreak and insufficient flowering, affecting fruit yield and quality. The key to achieving off-season blueberry production is to adjust the dormancy time of blueberry at the right time. It is worth noting that whether entering the low-temperature state by advancing dormancy or shifting into the growth period after dormancy is completed, temperature control must be carried out slowly, and the temperature difference must not be too large within a short time, so as not to affect the growth and development of blueberry. The greenhouse is in a sealed state. Because blueberry respiration and decomposition of soil organic matter can greatly change the gas composition inside the greenhouse and affect blueberry growth, proper ventilation must be carried out every day; generally, under the condition of not letting the greenhouse temperature drop below 12℃, open the ventilation passage at 11:00 every day and close it at 16:00.
4. Training and pruning of greenhouse blueberry:Pruning during the young tree stage. During this period, the main task is removing flower buds, with the purpose of expanding the canopy, increasing the number of branches, and promoting root development. In the second and third spring after planting, weak and small branches should be thinned out. In the third and fourth years, the main focus is still expanding the canopy, but a moderate amount of fruiting is allowed. Generally, in the third year, the yield per plant should be controlled below 1 kg, with fruiting mainly on strong branches. Pruning of mature trees. At this time, pruning is mainly to control tree height and improve light conditions, with thinning as the main method, removing overly dense branches, thin and weak branches, diseased and pest-infested branches, and root suckers. For varieties with a more spreading root habit, when thinning branches, remove the weak and retain the strong; for upright varieties, remove the central leader, open a "skylight", and retain medium branches. The best fruiting age for large branches is 5-6 years old; beyond that, they should be promptly renewed by heading back. For weak and small branches, remove the flower buds to make them grow stronger. Adult trees have a large number of flowers, so part of the flower buds should be pruned off. Generally, each strong branch retains 4-6 flower buds.
Image: Blueberry planting
V. Pollination of greenhouse blueberry
When growing blueberries in a greenhouse, the best pollination method is to combine bee pollination with artificial pollination. One beehive can be placed in each greenhouse during the flowering period, and pollination is carried out by bees, but some places may be missed. At this time, artificial pollination is needed as a remedy, and low-concentration gibberellin can also be sprayed to promote fruit enlargement. Experimental results show that keeping bees is currently the most economical, efficient and high-yielding method.
VI. Harvesting of greenhouse blueberry
The fruit ripening period of highbush blueberry is not uniform, and harvesting generally lasts 3-4 weeks, so harvesting should be done in batches, generally once every 1 week. After harvesting, place the fruit into plastic food boxes, then place them on shallow trays and transport them to the market for sale. Crushing, exposure to the sun, wind and rain should be avoided as much as possible.
[Editor's Conclusion]Using greenhouse planting techniques to grow blueberries is an important measure for achieving the goals of high yield, high quality and high efficiency in blueberry production, and is of great significance. The above has introduced the key points of greenhouse blueberry planting techniques for everyone, and I hope it can be helpful to everyone!
Key Points of Blueberry Planting Technical Management by Shanghai Minlan
In recent years, China's demand for blueberries has greatly increased. It is a blue berry with very high nutritional value, and its edible range is suitable for the general public. Therefore, Shanghai Minlan Blueberry Planting Professional Cooperative has become increasingly attentive to blueberry cultivation. So how does this cooperative grow them?
Soil improvement: Soil organic matter content and pH are important factors for the survival of blueberry cultivation. Generally, soil with an organic matter content of 5% and a pH of 4.0-5.5 is required; otherwise, improvement should be carried out. When the organic matter content is lower than 5%, river sand or sawdust, peat, rotten bark, etc. should be mixed into the soil before planting. When the soil pH (>5.5) or calcium content is too high, the pH needs to be lowered. A large number of studies show that applying sulfur is an effective measure for lowering soil pH. At present, sulfur powder is mostly used domestically and abroad to lower pH. The specific amount of sulfur applied should be determined according to different soil conditions and pH levels. If the soil pH is too low (<4.0)，常用石灰来调高pH值。
Planting blueberry: Planting can be done in both spring and autumn. The planting spacing for rabbiteye blueberry is 2.0 m × 2.0 m, for highbush blueberry 1.2 m × 2.0 m, and for lowbush blueberry 1.0 m × 1.0 m. Rabbiteye blueberry is self-unfruitful, so it is best to configure highbush blueberry as a pollinator tree. Highbush and lowbush blueberries have a relatively high self-fruit-setting rate, but configuring pollinator trees gives better results. The ratio of main cultivars to pollinator varieties is 1:1 or 1:2. After planted seedlings are established, fruit appears in the second year, and full production can be reached in the fifth year.
Soil, fertilizer and water management: Blueberry has a fibrous root system, and the roots are shallowly distributed, so fertilizer and water management should be strengthened. The principle of watering is to irrigate when dry and drain when waterlogged. Soil fertilization should be determined based on soil and leaf analysis. Blueberry is an oligotrophic plant, and fertilizer must never be applied in excess, so as to avoid fertilizer damage. Blueberry is sensitive to chlorine, so chlorine-containing fertilizers such as ammonium chloride and potassium chloride are not suitable; when applying nitrogen, ammonium nitrogen fertilizer is better. When planting blueberry, mainly NPK compound fertilizer is applied as topdressing, and farmyard manure is rarely applied. Li Yadong's research suggests: when cultivating blueberry on dark brown forest soil, applying NPK compound fertilizer at a ratio of 1:1:1 with an application rate of 500-1000 kg/hm2 gives good results. Highbush blueberry and rabbiteye blueberry use furrow application, while lowbush blueberry is mainly broadcast, with a depth of 10-15 cm being appropriate. Fertilization is carried out before budding in early spring, and can also be applied once more during the fruit ripening stage.