As an important economic crop, watermelon has become one of the high-profile crops in agricultural production because of its rich nutritional value, wonderful taste and wide market demand. However, to achieve high-yield, high-quality, and efficient watermelon cultivation, agricultural techniques need to be continuously improved and innovated. As a modern facility agriculture production method, arch shed cultivation technology provides new possibilities for the high yield and high quality of watermelon. The use of arches provides an ideal growing environment for watermelons, including reasonable control of light, temperature and humidity, thus helping to improve watermelon yield and quality.
1. The structure and materials of the arch shed.
Usually the length of the canopy is 50 meters and the width is 6 meters, and the length of the steel arch is about 9 meters. The net height inside the shed is 3 meters, and the distance between the arches is about 13 meters. The arch is composed of an arch trellis and a plastic film, and the arch material is galvanized pipe. The shed film is 004～0.08 mm thick drip-free film (Figure 1).
Fig.1 Schematic diagram of the height of the watermelon arch shed.
2. Variety selection and seedling management.
2.1 Variety selection.
When choosing watermelon varieties, it is necessary to consider factors such as planting environment, climatic conditions, and market demand. Choose from two common watermelon varieties:
8424: Early ripening, 28 30 days from flowering to fruit ripening; If the temperature is right, it will take 26-28 days. The fruit is round and spherical, and the skin is thin, 1About 1 cm, green in color, covered with bands of green flowers, clear and beautiful, with a pink pulp (Figure 2). The soluble solids content in the center is 12About 4%, and the soluble solids content at the edge is about 11%. The yield per mu cultivated by arch shed is 6000 to 8000 kg.
Fig.2 The surface of the watermelon 8424 is covered with green flower bands.
Mido: Medium-ripe, it takes about 40 days from flowering to fruit ripening at room temperature. The fruit is spherical to high, with a tougher and greener peel than 8424, covered with dark green stripes (the stripes are darker green than Zaojia 8424), and is more resistant to storage and transportation (Figure 3). The gourd is peach-colored, sweet and juicy, with a soluble solids content of 11% to 12% in the center and 8% to 9% soluble solids at the edges. The yield per mu can reach 6500 kg by arch canopy.
Fig.3 The surface of the watermelon is covered with dark green stripes.
2.2. Seedling management.
2.2.1 Seedling substrate and disinfection Usually humus-based, with an appropriate amount of organic matter added, and disinfection measures, such as steam disinfection or chemical disinfection, are used to kill pathogens and harmful microorganisms.
2.2.2 Temperature control By using heating equipment or greenhouse structures, keep the temperature of the nursery area within the appropriate range, usually 25-30 °C, to promote healthy seedling growth.
2.2.3 Humidity management Ensure that seedlings are not affected by drought by mulching nursery pots, using atomization systems, or mulching membranes to reduce water evaporation.
2.2.4 Light management Provide the right amount of light to ensure that the seedlings have sufficient photosynthesis efficiency, which can be achieved by light supplementation or mulch with adjustable light transmittance.
2.2.5 Pest Prevention Use physical or chemical methods, such as seed treatment, spray control, etc., to prevent the occurrence and spread of pests and diseases.
3. Cultivation and management of arched watermelon.
3.1 Planting density.
In the cultivation of watermelon in arch shed, the planting density and row spacing should be reasonably planned according to the arch shed structure, variety, soil conditions and management technology.
3.1.1 Row spacing setting The setting of row spacing should take into account the width of the arch shed, the height of the steel arch and the growth habit of the watermelon variety. In general, the row spacing within the canopy can be set at 12~1.5 meters. A large row spacing can provide more space, which is good for ventilation and light transmission of plants, but may reduce yield per unit area. Small row spacing can increase yield per unit area, but requires more detailed management.
3.1.2 Plant spacing The setting of plant spacing should be determined according to the growth habit of the watermelon variety and the light conditions in the arch shed. Typically, the plant spacing is 03~0.4 meters. For early-maturing varieties, small plant spacing is more suitable, as they tend to grow more compactly, helping to increase yields per unit area. For mid-late maturing varieties, a larger plant spacing can be left so that the plants have more room to grow.
3.1.3 Planting density The setting of planting density should take into account the area of the arch shed and the growth characteristics of the watermelon variety. In general, the planting density is 550 600 plants per acre.
3.2 Pruning.
3.2.1 The purpose of pruning is to control the growth of the plant, promote the balanced development of the main vine and the side vine, reduce the excessive vines and leaves, so that the plant can concentrate nutrients and energy for the growth of the fruit, and improve the quality and yield of the fruit.
3.2.2 Pruning time Pruning usually starts at the beginning of plant growth, and can be done when the vines reach a certain length. The time of pruning can be determined according to the growth rate of the watermelon variety and the space inside the arch shed.
3.2.3 Pruning method When pruning, prune off the overly long vines and unhealthy leaves, leaving the main vine and healthy side vines. Use scissors or pruning knives for pruning, making sure the incision is flat and avoiding an excessively large wound. After pruning, the pruned vines and leaves are cleared out of the arch shed to reduce the occurrence of pests and diseases.
3.3 Pollination techniques.
3.3.1 Artificial pollination In arch sheds, artificial pollination is a commonly used technique to increase the fertilization rate of fruits. Pollen from male flowers is gently brushed onto the stamens of female flowers, usually using a fine-bristled brush or small brush, simulating the natural pollination process. Pollination usually takes place in the morning, when the pollen viability of male flowers is strongest (Figure 4).
Fig.4 Watermelon pollination.
3.3.2 Insect pollination The release of Chinese bumblebees, which are not sensitive to temperature, for pollination, can greatly improve the fertilization rate and fruit commerciality, reduce the labor intensity of workers, and improve economic benefits.
3.3.3 Male and female flower control In order to improve the efficiency of pollination, the ratio of male and female flowers can be controlled as needed. A certain percentage of male flowers is usually reserved to ensure an adequate supply of pollen. Female flowers are usually the ones that produce fruits, so care should be taken to strengthen protection.
3.4 Fruit Set Marking.
3.4.1 Purpose of Fruit Set Marking The purpose of fruit set marking is to record the pollination date of each fruit in order to determine the best time to pick, helping to improve the ripeness and taste of the fruit.
3.4.2 Marking Methods Use different colored marker sticks or labels to mark the pollination date of each fruit. Typically, 5 different colored marker sticks are used, with 1 color inserted every 2 days for a total of 5 insertions, to determine the pollination date range of the fruit.
3.4.3 Recording and management After fruit set marking, the pollination date of each fruit needs to be recorded and tracked in daily management. Based on the pollination date, the ripening time of the fruit is estimated and the harvest is carried out at the best time for picking.
4. Irrigation, fertilization and pest control.
4.1 Irrigation management.
4.1.1. Regular irrigation The irrigation in the arch shed needs to be reasonably arranged according to the growth stage and climatic conditions of the watermelon. In general, watermelons need to keep the soil moist at the beginning of their growth, but do not overwater them to avoid suffocation of the root system. As grows, gradually reduce the frequency of irrigation, but keep the soil moderately moist to prevent insufficient water pressure from affecting fruit quality.
4.1.2 Drip Irrigation System Inside the arch shed, the drip irrigation system is an efficient way of irrigation. It can accurately control the amount of water, reducing water waste and disease spread. Drip irrigation systems can also provide water directly to the root zone of the plants, improving water use efficiency.
4.1.3 Irrigation under mulch Irrigation under mulch is a method of delivering water directly below the root system, reducing water evaporation and pest and disease spread.
4.2 Fertilization strategies.
4.2.1 Combination of organic fertilizer and chemical fertilizer In the cultivation of watermelon in arch sheds, the fertilization strategy of organic fertilizer and chemical fertilizer is usually adopted. Organic fertilizers improve soil structure and provide trace elements, while fertilizers provide the main nutrients such as nitrogen, phosphorus and potassium.
4.2.2 Top dressing strategy Add an appropriate amount of fertilizer according to the growth stage of watermelon to meet its needs. The time of top dressing usually includes the seedling stage, vine growth stage, flower and fruit stage, etc. The way of top dressing is mainly combined with watering to adopt the integration of water and fertilizer, the use of all-element instant fertilizer, and foliar fertilization can also be combined with pest control. Foliar fertilization can provide nutrients quickly, especially micronutrients.
4.3. Pest and disease control measures.
4.3.1 Precautionary measures In the arch shed, the growth of plants should be checked regularly, the early symptoms of pests and diseases should be found in time, and measures should be taken to prevent and control them.
4.3.2 Physical control Set up an appropriate amount of sticky insect board in the shed, and install insect-proof screen in the ventilated place to reduce insect pests.
4.3.3 Biological control The introduction of natural enemies and probiotics to control pests and pathogens can effectively control pests and diseases.
4.3.4 Chemical control When necessary, high-efficiency, low-toxicity and low-residue pesticides can be used to control pests and diseases, and should be used cautiously, in accordance with the instructions for the use of pesticides, to ensure people's "safety on the tip of the tongue" and the safety of the ecological environment.
4.3.5 Deep ploughing and crop rotation Through deep ploughing and crop rotation, the accumulation of pests and diseases in the soil is reduced and the healthy growth of watermelon is promoted.
5. Watermelon harvesting.
5.1 Harvest time.
5.1.1 According to the ripeness of the fruit Usually, the color of the peel changes from green to dark green, and some varieties turn light yellow, which is one of the signs of ripeness. In addition, when you tap the melon shell, you should hear a deep sound, not a dull sound (Figure 5).
Fig.5 Professional technicians inspecting the ripeness of watermelon.
5.1.2 By pollination date Fruit set markers can be used to record the pollination date of the fruit. Based on the pollination date, estimate the ripening time of the fruit. Generally, it takes around 5 weeks from pollination to maturity.
5.2 Harvesting Method.
5.2.1 Fruit Pedicle Cutting Method Cutting is a common harvesting method. Carefully cut off the fruit pedicle with a knife or scissors, leaving a small part of the fruit pedicle connected to the fruit. Once cut, the fruit is easily detached from the vine.
5.2.2 Basket picking For large-scale production, the basket picking method is more effective. When picking, carefully unscrew ripe watermelons from the vines and place them in a basket or collection container to prevent damage.
6. Conclusion.
The high-yield, high-quality and efficient cultivation technology of arched watermelon has significant potential in increasing the yield of agricultural products, improving the quality and protecting the environment. It is hoped that this article can help the majority of melon farmers and agricultural practitioners to promote the sustainable development of watermelon cultivation in arch sheds, so as to contribute to agricultural production and food safety.