Detailed Explanation of Key Techniques for Cold Shed Grape Cultivation
A cold shed refers to a plastic greenhouse, which does not need straw mats and has only a single layer of plastic film. Growing grapes in a cold shed is a low-investment, easy-to-manage project that can bring grapes to market 1 to 2 months earlier. So, what are the cold shed grape cultivation techniques?
1. Variety selection
Choose varieties with strong productivity, high temperature tolerance, good storage and transport tolerance, a short dormancy period, a short fruit development period, early maturity, moderate growth, and disease resistance, such as Kyoho and others.
2. Cold shed construction
Choose a plot with flat terrain, fertile soil, shelter from the wind and facing the sun, and convenient irrigation and drainage to build the orchard. Use a north-south orientation as much as possible, facing south with its back to the north. The shed height should preferably be 3 to 3.7 m (able to hold 5 layers of film), and the width should preferably be 18 to 24 m. Too narrow is not conducive to early heat preservation, while too wide is not conducive to ventilation and cooling.
3. Planting management
Planting density varies according to many conditions such as variety, site conditions, training method, and seedling resources. Generally, for a small trellis, the plant spacing is 0.5 to 0.8 m and the row spacing is 4 m. Before planting, apply sufficient base fertilizer; only by establishing the orchard to high standards can high benefits be obtained. The planting method is the same as conventional tree planting.
4. Pruning
Complete pruning around the beginning of winter and bury the vines in soil to protect against cold. Use short-spur pruning, remove overly dense branches, thin and weak branches, and diseased and pest-damaged branches. Leave 1 fruiting branch about every 30 cm, evenly distributed in opposite directions.
5. Fruit thinning
One week before flowering, thin out weak and excessive flower clusters, leaving about 7 fruit clusters per 1 sq m of trellis surface. When the fruit clusters begin to color, appropriately thin out overly dense new shoots on the trellis surface and shading leaves near the fruit clusters to improve light and promote coloring. Leave 1 cluster on strong fruiting branches and none on weak fruiting branches, and at the same time pinch off the tip of the main cluster at 1/5 to 1/4 of the cluster tip. From when the berries are the size of soybeans, carry out berry thinning until harvest. During the fruit enlargement period, mainly thin out small, diseased, and overly dense berries so that the cluster takes on a neat, nearly conical shape. During the harvest period, focus on removing diseased berries and poorly colored green berries.
6. Temperature and humidity regulation
Temperature: Temperature is the key to cold shed grapes. The daytime temperature should be 15 to 25%, and at night not lower than 8°C; from sprouting to before flowering: 18 to 25°C during the day; around the flowering period, the temperature should be slightly higher, 25 to 28°C during the day and 18 to 22°C at night; from fruit set to the fruit enlargement period: 25 to 32°C during the day and 15 to 18°C at night; from fruit coloring to the harvest period: not higher than 30°C during the day and around 15% at night, widening the day-night temperature difference to promote fruit coloring and sugar accumulation.
Humidity: High temperature and low humidity inside the shed are key to avoiding grape diseases. For air humidity in the shed, from sprouting to the flower cluster extension stage it is about 80%, after the flower clusters extend it drops to 70%, from flowering to fruit set it is 65% to 70%, and after fruit set it is maintained at 75% to 80%. For soil moisture, from shed covering to harvest, the relative soil water-holding capacity should be maintained at 60% to 80%. Within different phenological periods, the water requirement is relatively large during sprouting and the fruit enlargement period, and it should preferably be controlled within the range of 70% to 80%. During fruit growth and development, try to avoid excessive fluctuation in soil water content to prevent fruit cracking.
7. Fertilizer and water management
Apply base fertilizer in autumn. For trench application, mainly use organic fertilizers such as sheep manure and barnyard manure. For young trees, the application rate per 667 sq m should be no less than 3 m3. For mature trees, the application rate should be no less than 4 m3. After sprouting, apply 25 to 30 kg of urea per 667 sq m as a top dressing. When new shoots grow to about 10 cm, use a 0.3% to 0.5% urea aqueous solution for foliar top dressing. Afterward, do this once every 10 to 15 days, which can improve the high-temperature resistance of young shoots. During the fruit enlargement period, apply a high-nitrogen fertilizer containing trace elements and secondary elements, “Song'er”, and apply it again after 25 to 30 days; during the initial fruit coloring period, combine with a 0.3% to 0.5% potassium dihydrogen phosphate aqueous solution for foliar top dressing. For freezing water, sprouting water, fruit enlargement water, and so on, determine whether to irrigate based on soil moisture conditions, and irrigate immediately after each fertilization.
8. Pest and disease control
Before covering the shed, clean up dead branches, fallen leaves, rotten fruit, and so on, and burn them in a centralized manner. During winter pruning, cut off diseased branches and vines and remove old bark carrying pathogens. Control flowering-period diseases and red spiders, and so on. At other times, as the situation requires, spray 1 to 2 times with 0.3% matrine aqueous solution at 600 times dilution + 50% dimethomorph (Anke) wettable powder at 1500 times dilution to control various grape pests and diseases. For controlling grape gray mold by smoking, it is best to do it after finishing work.
Cold shed grape cultivation requires adapting to local conditions according to climate, environment, and other factors in each area, and reasonably controlling temperature and humidity.