Six Essential Points of High-Yield Grape Cultivation You Must Know
Grapes are a fruit that many people love to eat, with a great many varieties and rich nutritional value. In autumn, grapes are inexpensive and delicious, sweet and juicy. To enjoy even more delicious grapes, scientific grape cultivation is necessary. For grapes to be high-yield, six essential points of cultivation techniques you must know.
I. Key Points of Grape Cultivation Techniques
1. Variety Selection
Generally, choose early-maturing varieties suitable for short-spur pruning, with low chilling requirements, easy flower bud formation, and tolerance to high temperature and high humidity in greenhouses, such as Victoria, Fujiminori, Gold Finger, Thompson Seedless, and Red Seedless.
2. Selection of Orchard Site and Cultivation Method
For good light exposure, the orchard should be sheltered from the wind and facing the sun, with no tall obstructions. The soil should preferably be well-aerated sandy loam on flat terrain. Never establish an orchard on heavily saline-alkaline land, low-lying land, or land with continuous cropping of the same crop. Cultivation methods include plastic tunnels and solar greenhouses; in the Hengshui area, plastic tunnels are predominantly used.
3. Training and Pruning
Generally, a trellis or hedge system is used. Pruning time is from after leaf fall to before bleeding, that is, from late November to the end of January the following year. After winter pruning, leave 3600 fruiting mother canes per mu, and regulate the number of shoots and clusters retained through bud rubbing and shoot thinning. Pinch the growing tips of fruiting canes after 10 leaves, and of vegetative canes after 15 leaves. Pinch the top lateral shoots of both fruiting and vegetative canes after 8 leaves, and other lateral shoots after 5 leaves. Girdling before and after flowering can increase the fruit-setting rate; girdling before fruit ripening and coloring can promote fruit maturation and improve quality. Girdling before fruit ripening is best done 15 days before harvest.
4. Flower and Fruit Management
Twist the upper part of the inflorescence 8 to 10 days before flowering. When 6 to 7 leaves have unfolded, thin the clusters, removing deformed berries, small berries, diseased and pest-damaged berries, and overly crowded berries from the clusters. Strong fruiting canes retain 1 to 2 clusters, moderate canes retain 1 cluster, and weak canes retain none. For varieties with severe flower and fruit drop, flower and fruit preservation treatments are needed, dipping the clusters in 10 mg/kg gibberellin plus 2 mg/kg forchlorfenuron.
5. Fertilizer and Water Management
Autumn basal fertilizer: from late August to late September, apply per mu 5000 to 6000 kg of fully decomposed organic fertilizer, 30 to 40 kg of compound fertilizer, 50 to 80 kg of silicon-calcium-magnesium-potassium fertilizer, 15 kg of superphosphate, 1.5 kg of borax, and 2 kg of zinc sulfate. Organic fertilizer should be mainly cattle and sheep manure; chicken manure should not be applied because it contains urokinase, antibiotics, caustic soda, and heavy metals.
6. Pest and Disease Control
In winter, clean up diseased and mummified fruit, as well as diseased and pest-infested branches and leaves in the orchard to reduce pest and disease sources in the tunnel. Before bud break, spray 3 to 5 degrees Baumé lime sulfur to control downy mildew, powdery mildew, black spot, and spider mites. Before and after flowering, spray 200-fold Bordeaux mixture twice consecutively to control black spot. From bud break to before flowering, spray the whole orchard with 1000-fold Daconil M-45 wettable powder plus 1500-fold Lorsban to control gray mold and plant bugs. During the fruit growing period, spray 2000-fold mancozeb wettable powder to control anthracnose and white rot.
II. How Do Grapes Change Color?
Many factors affect grape coloration, including temperature, light, yield, rational fertilizer use, irrigation amount, whether the leaf-to-fruit ratio is reasonable, pesticide use, and functional fertilizer use. In addition, poor roots or overly weak tree vigor, as well as severe pests and diseases, can all have a certain impact on grape coloration.
1. Temperature and light mainly affect sugar accumulation and the activity of enzymes in the plant.
Light can affect the synthesis of sugars and related organic compounds, and is also greatly related to anthocyanin synthesis. Therefore, during normal production of grapes in protected warm tunnels or cold tunnels, always try to maximize light duration. As long as the temperature is adequate, roll up the straw curtains or cotton quilts early and lower them late. As for temperature, the mechanism of anthocyanin formation is complex, and the day-night temperature difference is crucial for sugar accumulation. The most suitable temperature during the coloration period is 25 to 30 degrees during the day, and never exceed 30 degrees; at night, 12 to 15 degrees, and it must not fall below 10 degrees. Below 10 degrees, grapes almost stop growing. Do not extremize this by understanding it as having no upper or lower limits for high or low temperatures; either too high or too low will cause obstacles to grape coloration.
2. Reasonable load.
According to the specific condition of the tree vigor, maintain a reasonable load. The best yield per mu is controlled at 3000 to 4000 jin, and the maximum should not exceed 5000 jin. For overly large clusters, do a good job of cluster trimming and berry thinning. In addition, for protected cultivation grapes, it is best not to interplant small vegetables at the front lower corner or between grape rows. Although this does not affect grape yield, the vegetables completely absorb during the day the light that should have radiated to the ground, and the advantage of using the ground to absorb light and raise ground temperature is entirely lost. Moreover, in warm tunnels or cold tunnels with interplanted small vegetables, as soon as the sun sets or the straw curtains are lowered, the temperature inside the tunnel drops rapidly. But in tunnels without interplanted small vegetables, the ground or back wall releases the heat stored during the day, thereby ensuring that the night temperature increases by at least 3 to 5 degrees. The more accumulated temperature there is, the faster the grapes color. Therefore, although grape tunnels with interplanted small vegetables do not reduce yield, the selling price is greatly discounted because the grapes come to market a week later or even later.
3. Fertilizer aspects.
Rational use of fertilizers with various elements at different stages is the most important link affecting how quickly grapes color. Coloration is not something to rush. During normal management, suitable conditions should be created so that grapes color quickly. Therefore, doing a good job of routine nutrient accumulation is very important. At the most basic level, in one growth cycle of grapes, three fertilizer applications are indispensable: autumn fertilizer, bud-break fertilizer, and fruit-swelling fertilizer. Especially for autumn fertilizer, the amount used should be 60% to 70% of the whole year. Autumn fertilizer must be applied heavily so that the grape vines will be stronger the following year. Many farmer friends are very greedy and generally do not pay much attention to these fertilizer applications, saving wherever they can and relying mainly on water flushing, which cannot meet the needs of the tree body, so coloration naturally becomes difficult.