Key Technical Points for High-Yield Open-Field Watermelon Cultivation in Spring
It is currently the season for sowing and raising seedlings of open-field watermelons. To do a good job of watermelon cultivation and increase farmers' income, the key technical points for spring open-field watermelon cultivation are introduced as follows: 1. Variety selection. Varieties should be chosen according to market demand, selecting those that are well-suited to the market, with good quality, high yield and strong disease resistance, such as Qinghong...
It is currently the season for sowing and raising seedlings of open-field watermelons. To do a good job of watermelon cultivation and increase farmers' income, the key technical points for spring open-field watermelon cultivation are introduced as follows:
1. Variety selection
Varieties should be chosen according to market demand, selecting those that are well-suited to the market, with good quality, high yield and strong disease resistance, such as Qinghongbao, Heifeng Bawang, Jingfengbao, etc.
2. Selection of the planting site
The plot for planting watermelons should be a leeward, sunny, level field; continuous cropping must not be used. It is best to choose a plot with convenient drainage and irrigation, deep soil layers and rich organic matter.
After deep plowing and sun-drying the soil for half a month, break up the soil and prepare the beds, making inclined beds 2.5 m wide including the trench, with one side of the bed 40 cm high and the other side 20 cm high; on the side near the high bed, dig a planting trench 25 cm deep and 40 cm wide. In the trench, apply per mu 1000-1500 kg of decomposed farmyard manure, 25 kg of ternary compound fertilizer, 1.5-2 kg of borax and 4 kg of magnesium sulfate. When applying in the trench, the fertilizer should be mixed evenly with the backfilled soil.
3. Seed soaking
Select plump watermelon seeds and soak them in warm water at 55°C, stirring constantly. When the water temperature drops to 30°C, continue soaking for 5 hours, wash off the mucus on the seed coat, drain off the water and sow promptly.
4. Sowing at the proper time
For early-spring open-field watermelon fields covered with plastic film, the sowing period should preferably be late April. The sowing method is dibbling in the middle of the plastic film, with 2-3 seeds per hole and a sowing depth of 2 cm. After dibbling, cover flat with fine soil and press firmly. Generally, the seed rate is 200 g per mu.
5. Seedling-stage management and seedling density
After emergence, pay attention to ventilating the seedlings in time to prevent them from being scorched to death. Watermelon seedlings can be transplanted when they have 3-4 leaves. The planting density per mu is 600-700 plants for large watermelons and 700-800 plants for small watermelons.
6. Field management
1. Fertilizer and water management. When fertilizing, be careful to apply seedling-promoting fertilizer sparingly, apply vine-extending fertilizer skillfully and apply fruit-swelling fertilizer heavily. The seedling-promoting fertilizer is applied 5-7 days after transplanting, once the seedlings have recovered; generally, urea and compound fertilizer are mixed in a 1:2 ratio to make a 0.3% solution and applied once. The vine-extending fertilizer is generally applied about 20 days after the seedling-promoting fertilizer; use 10-15 g of urea and 15 g of potassium fertilizer per plant, open 25 cm deep strip trenches on both sides 35 cm away from the transplanting point, apply the fertilizer in the trenches and cover with soil. The fruit-swelling fertilizer is applied when the young fruit is the size of an egg; use 30-40 g of urea, 15 g of superphosphate and 30-40 g of potassium fertilizer per plant, applied 50 cm away from the transplanting point. The application method is the same as for the vine-extending fertilizer, but the trench position should be perpendicular to the vine-extending fertilizer trench.
For spring-planted watermelons, drainage after rain must be done promptly so that the trenches dry once the rain stops. If high temperature and drought occur during fruit setting, furrow irrigation can be used at night, but the bed surface must be kept slightly dry and drained promptly.
2. Intertillage and weeding. Intertillage and weeding should be carried out when the watermelon vines are 40-50 cm long. If the vines are too long, intertillage is not only inconvenient but also likely to damage the vines and leaves, allowing pathogens to invade; moreover, the loosened soil is easily splashed onto leaves, flowers and young fruits after rain.
3. Pruning and vine training. Common pruning methods include the two-vine system and the three-vine system. In the two-vine system, the main vine and one strong side vine at the base of the main vine are retained, and the other side vines are removed early. This method is suitable for dense planting and has a high fruit-setting rate, and is more often used in early-maturing cultivation or in relatively barren plots. In the three-vine system, the main vine is retained, and 2 strong side vines are selected from the third to fifth nodes at the base of the main vine, with other side vines removed. This method is more commonly used for mid- and late-maturing varieties. From the time the main vine emerges until the first female flower opens, tidy the watermelon seedlings once every 3-4 days so that the main vine extends forward in an orderly way. After flowering, no more vine training is carried out.
4. Artificial pollination. Spring-planted watermelons are prone to continuous rainy weather, which affects insect activity, so artificial pollination can be used to increase the fruit-setting rate.
5. Promoting fruit setting. It is ideal to select and retain the second and third female flowers on the main vine for fruit setting. Fruits set from female flowers very far from the main root are also smaller and generally should not be retained.
6. Fruit management. In the process of multi-vine pruning and free cultivation, sometimes a plant sets several fruits or the fruit-setting node is not ideal. At this time, fruit thinning measures should be taken, removing young fruits at low nodes or with irregular shape, disease or injury, so as to retain and ensure the development of normal fruits at normal nodes.
7. Pest and disease control
Integrated control measures should be adopted for watermelon pest and disease control.
1. Agricultural control. First, clear the weeds on the ditches and roadsides near the watermelon field to reduce the hosts available to pests in the early stage; second, pay attention to removing diseased watermelon plants. Diseased plants should be pulled up and deeply buried or burned in a centralized manner, and should not be casually discarded in ditches or by the roadside.
2. Chemical control. To control Fusarium wilt, drench the roots once with a 500-fold solution of 50% carbendazim wettable powder or a 1000-fold solution of 70% thiophanate-methyl, applying 250 ml of the solution per hole. Viral diseases are mainly transmitted by aphids, so the key is to control aphids to prevent the disease. Before the aphid peak, spray a 1500-fold solution of 20% imidacloprid for control. When virus-diseased plants are found, spray a 600-fold solution of 20% Virus A, once every 7 days, for 2-3 consecutive times. In the early stage of anthracnose, spray a 800-fold solution of 80% anthracnose Fumei or a 500-fold solution of 70% thiophanate-methyl wettable powder.
8. Harvest
30-35 days after pollination, the fruits mature and can be harvested for market. When harvesting, retain the fruit stalk and a section of the vine, which not only prevents pathogen invasion but also has a certain fresh-keeping effect.