Detailed Explanation of Greenhouse Dwarfing and High-Density Planting Cultivation Techniques for Sweet Cherry

I. Site Selection

Select fertile soil with deep soil layers, neutral or slightly acidic loam and sandy loam for orchard establishment. The groundwater level must be low with no water accumulation.

II. Rootstock and Variety Selection

Select Gisela 6, which is dwarfing and has strong stress resistance and adaptability, as the rootstock. Select early-maturing and mid-early-maturing varieties with small canopies, early fruiting, high yield and short chilling requirements, such as Zaorenguo, Hongdeng, Meizao, Short-branch Stella, Lapins, Summit and other varieties.

III. Planting Density and Pollinator Tree Configuration

Use Gisela dwarfing rootstock seedlings for planting, adopt a clump-shaped tree form, with a planting spacing of 2 m x 3 m between plants and rows. For transplanting large trees, the spacing can be appropriately increased. The ratio of main varieties to pollinator varieties is 3:1 or 3:2. Main varieties and pollinator varieties should be planted in north-south rows, alternating by row.

IV. Film Mulching and Temperature Raising

Sweet cherry has a long dormancy period. The minimum chilling requirement at 0°C-7.2°C is 600-700 hours, and the longest reaches about 1400 hours. Temperature raising should be carried out after natural dormancy is completed. In the Tang-Qin region, generally at the end of October, when the outside temperature reaches 0°C, cover with film and quilts, open the ventilation openings, and keep the temperature below 7.2°C. From December 17 to 27, cover the greenhouse and raise the temperature. At this time, open the quilts during the day and roll them up at night.

V. Management Inside the Greenhouse

1. Temperature and humidity regulation. Temperature and humidity regulation at each stage inside the greenhouse is very critical and must be strictly controlled. From bud break to flowering stage, daytime temperature 16°C-20°C, nighttime temperature 7°C-9°C, soil temperature 14°C-16°C, air humidity 70%-80%: young fruit stage, daytime temperature 20°C-22°C, nighttime temperature 8°C-12°C, soil temperature 16°C-20°C, air humidity 50%-60%: coloring to fruit ripening stage, daytime temperature 22°C-25°C, nighttime temperature 12°C-15°C, soil temperature 18°C-22°C, air humidity 40%-50%. Place 2-3 automatic temperature and humidity recorders in each greenhouse and connect them to the skylight. When the temperature reaches the set temperature, the skylight automatically opens for ventilation and cooling, and closes promptly when below the set temperature. Roll up the quilts during the day and put them down at night. Temperature is mainly regulated through ventilation and uncovering or covering cotton quilts. Before raising the temperature, irrigate the soil once thoroughly, and cover with plastic film to increase soil temperature. After raising the temperature, maintain soil relative water content at 60%-70%. Do not water during the 1 week before and after the flowering period. During the fruit development period, watering should be done in small amounts and multiple times, preferably by micro-sprinkling or surface watering, to avoid excessive changes in soil water content that cause massive flower and fruit drop and fruit cracking.

2. Flower and fruit management.

Improving fruit set rate: Combine bee pollination with artificial pollination. Place bees in the greenhouse 7-10 days before flowering to allow them to adapt, otherwise the bees will not fly out, and artificial pollination must also keep up. Spray 30 mg/L gibberellin (920) + 0.3% borax solution once each before and after the full flowering stage to improve the fruit set rate.

Flower and fruit thinning: During the germination and flowering stage, remove poorly developed small flower buds, deformed flowers, double-pistil flowers, and late-opening weak flowers. After physiological fruit drop, remove small fruits, weak fruits, and deformed fruits. Cut back and renew thin and weak branches as well as branches bearing excessive fruit.

Promoting fruit enlargement and coloring: From the fruit enlargement stage to the coloring stage, when new shoots grow to 20 cm, pinch the tips to reduce nutrient consumption, improve fruit set rate, and increase single fruit weight: from after flower drop to before harvest, alternately spray 0.3% urea and 0.3% potassium dihydrogen phosphate solution every 10 days, and appropriately increase the application of water-flushed organic fertilizer.

3. Soil, fertilizer and water management. Before flowering, combine with watering and apply 1.5-2 kg of organic compound fertilizer per tree. After fruit harvest, apply fully decomposed cow manure at more than 6 cubic meters per mu. Pay attention to watering during the bud break stage, before flowering, the hard core stage, and the coloring stage. At these times, water in small amounts and multiple times, control moisture, and prevent excessive new shoot growth and fruit cracking.

4. Pest and disease control. Before the temperature drops in late November, clean the ground and remove weeds, dead branches and fallen leaves. Spray 5 degrees Baume lime sulfur mixture once before bud break.

In mid-May, spray chlorpyrifos and azocyclotin to control spider mites and Phalera flavescens caterpillars. In late June, continue spraying azocyclotin to control spider mites, and combine with emamectin benzoate to control leaf roller caterpillars. From late July to early August, spray polyoxin to control leaf spot disease. Basically no pesticide is used from flowering to fruit ripening stage.

VI. Management After Fruit Harvest

1. Remove covers. After fruit harvest, gradually increase ventilation openings so that the temperature and humidity inside the greenhouse gradually approach the outside, and after about 15 days completely remove the film. If summer temperatures are too high, cover with shade netting from 10:00 AM to 03:00 PM to prevent high temperatures inside the greenhouse from scorching leaves.

2. Soil, fertilizer and water management and training and pruning. After fruit harvest, apply decomposed cow manure in furrows to provide sufficient nutrients for flower bud differentiation. Control moisture well to ensure the tree is neither short of water nor subjected to waterlogging damage. Strengthen pruning during the growing season, mainly removing excess upright branches, aged branches and drooping branches. If the number of branches is insufficient, pinch the tips of vigorously growing new shoots on the upper side of branches multiple times.