Detailed Explanation of Key Techniques for High-Yield Cultivation of Greenhouse Cherries

Greenhouse cherries require low input and yield high returns. Using greenhouse cultivation in early spring can bring cherries to market ahead of time and achieve considerable economic benefits. In our town's nursery plots, through greenhouse trials, we consistently achieved fruiting in three years and yields exceeding one thousand jin per mu in five years. When shipped to Qingdao, Yantai and other places, they sold out quickly. Income per greenhouse reaches more than 30,000 yuan, giving it extremely high economic value. The technical measures are summarized as follows:

I. Choosing a suitable site

1. When building the greenhouse, choose loam or sandy loam that is sheltered from the wind and faces the sun, has sufficient light, level terrain, convenient drainage and irrigation, and loose soil. According to the greenhouse's heat dissipation conditions, a greenhouse area of 300-400 sq m is appropriate.

2. Timely covering of the greenhouse

Generally, it should be built as an east-west oriented single-slope greenhouse. To reduce costs, the north wall can be made of earth. The east and west walls are 3 m high, and at 2 m from the north wall the height is 3.5 m. Gypsum strips (with steel bars inside) are used for support. The south wall is 2.5 m high, and the east and west walls each have a working door and ventilation windows. The windows are 1.5 m above the ground, and the inner sides of the north and south walls are all sealed with mud plaster (except the windows). This is used to prevent cold and preserve heat. Inside the greenhouse, gypsum strips (with steel bars inside) serve as the main columns. The row spacing and column spacing are 3.5 m. Above the upright columns, moso bamboo is used as the framework, connecting the south wall and north wall, tied into a 50 cm square grid, covered with dripping-free film. A layer of straw curtains is then laid over the film. The time for covering the greenhouse should be controlled between late December and early January.

II. Variety selection

1. The purpose of establishing a greenhouse cherry orchard is to bring cherries to market earlier and obtain higher economic benefits, so in variety selection, excellent varieties with early maturity and a high self-pollination fruit-setting rate should be chosen. Such as Hongdeng, Dahong, Zhusha, Jianye and other varieties. At the same time, pollinizer trees should be arranged at a ratio of 4:1 (such as Lapins or Stella). This prevents situations such as low self-fruit-setting rate and poor quality.

2. Use strong seedlings or strong trees for dense planting cultivation.

In order to use land more economically and see benefits earlier, cherry seedlings should be selected as strong seedlings with robust roots, many fibrous roots, thick and sturdy nursery stock, and plump buds, or 5-8 year old early-fruiting trees that are relatively short with more inner-canopy branches. The rootstock should be selected as seedling rootstock of mountain cherry, and dwarfing rootstock (such as Laiyang dwarf cherry) should be used as interstock.

For strong trees that have already fruited, an appropriate amount of paclobutrazol should be sprayed to inhibit their growth. The planting density of strong seedlings in the greenhouse should be controlled at a plant and row spacing of 2 m × 3 m or 1 m × 2 m, and strong seedling trees can be controlled at 3 m × 4 m.

III. Training and pruning.

1. For convenient training and pruning, mainly adopt the natural open-center form or the free spindle form. These tree forms have small crowns, are suitable for dense planting, and are easy to train and bear fruit early. Cherry trees grow vigorously, with upright posture, and are not easy to spread open. In spring, when sap flows, or after August-September in autumn, use the apple branch-bending method. The opening angle is generally 50-80 degrees, to moderate tree vigor and increase flower formation. To promote branching and help flower bud differentiation, before spring bud break, shorten the growing branches to encourage new shoots and expand the crown. For branchless positions or lateral buds on long branches, notch the buds to promote new shoots and increase fruiting branches. In summer, pinch the new shoots; when the extended long branch of the main branch and the central leader branch grow to 30-40 cm, the terminal shoot can be cut back by 10 cm, while the remaining branches and upper main branches are heavily shortened leaving 5-10 cm. Vigorously growing branches can be pinched twice, and strong upper branches can be continuously pinched to promote the formation of fruiting branch groups.

2. Application of paclobutrazol

Apply paclobutrazol 2-3 years after planting, when the tree has a relatively large number of branches, and the flower-promoting effect is significant. The application method can be soil application or spraying, and the suitable time is late April to late May. Generally, for 2-3 year old trees, apply 1.5 g per tree; for strong trees, apply 3 g per tree.

3. Improving fruit-setting rate and fruit quality

Because the temperature inside the greenhouse is relatively high and ventilation is poor, auxiliary pollination during the flowering period is very important. Bees can be released or artificial pollination can be used to increase the fruit-setting rate. At the same time, every 10 days spray 0.3% urea + 0.3% borax or 0.5% potassium dihydrogen phosphate solution to increase the fruit-setting rate. In the early stage of fruit coloring, appropriately remove leaves that block light; lay reflective film under the tree canopy; for single-slope greenhouses, pull reflective curtains on the north wall, and at the same time spray twice with “Hongguo 88” to promote fruit coloring and earlier ripening.

IV. Soil, fertilizer and water management

Cherries are very sensitive to soil moisture conditions, being neither drought-resistant nor tolerant of waterlogging. Therefore, it is necessary to choose soil with good looseness and air permeability, use less quick-acting chemical fertilizer, and use more organic fertilizer. Cherry watering does not require large-volume flooding irrigation; it only requires that “water passes and the ground surface becomes wet.” Apply one round of fertilizer before bud break, mainly nitrogen fertilizer. In February-March, apply special fertilizer for fruit trees, with 0.2-0.4 kg per tree. At the same time, according to actual conditions, carry out 1-2 foliar fertilizer sprays during the flowering and fruiting period. After fruit harvest, mainly use phosphorus and potassium fertilizers to promote flower bud differentiation. Apply base fertilizer in autumn, mainly farmyard manure, with 2000 kg of farmyard manure per mu. Each of the above fertilizer applications should be followed by one watering.

V. Temperature regulation in the greenhouse

Temperature regulation inside the greenhouse is very critical for greenhouse cherries. Once it is not controlled reasonably, freezing injury may occur, causing low fruit-setting rate, rotting of fruit and leaves, and similar phenomena. Therefore, after covering the greenhouse, special attention should be paid to temperature regulation. Within 3-4 days after covering the greenhouse, the working doors and ventilation windows should be fully open. From 3-10 days, gradually close the working doors and ventilation windows. After 10 days, gradually cover all straw curtains at night to raise the temperature. When the temperature rises to 16°C, ventilate and exchange air every day from 10:00 to 17:00, and after 17:00 close the ventilation windows and cover the straw curtains (uncover the straw curtains after the sun comes out each day). From after covering the greenhouse to before flowering, the temperature inside the greenhouse should be controlled by covering plastic film. The suitable humidity is 70%-80%, and the suitable humidity during the flowering period is 50%-60%, which can be controlled by placing moisture absorbents. The suitable humidity from young fruit to coloring stage is 60%-70%, which can be controlled by ventilation and air exchange. From coloring to harvest period, the suitable humidity is 60-70%, and ventilation is needed until the film is gradually removed. After the harvest period, the film can be completely removed, and fertilizer and water should be applied, strengthening underground management.

VI. Pest and disease control

The main diseases of cherry trees are peach bacterial shot hole and cherry leaf spot. Before bud break, spray the whole tree once with 5 degrees Baume lime sulfur mixture. In late June and late July, spray the leaves once each with 200-fold lime excess Bordeaux mixture, which can also simultaneously control stinging caterpillars and other leaf-eating pests.