Small arch sheds combined with plastic film covering are widely used in watermelon cultivation due to their low cost, ease of management, and high efficiency. To achieve optimal results, the following key technologies should be mastered:
**Selection of Improved Varieties**
Choose early-maturing, cold-tolerant, light-resistant, disease-resistant, and transport-friendly varieties such as Jingxin No. 1 and Baifeng No. 3. Seedless watermelon varieties like Heimi No. 2 and Huaxia No. 2 are also available and offer added convenience for commercial production.
**Timely Planting and Strong Seedling Cultivation**
Sow seeds from late February to late March, transplant seedlings in early April, and expect harvests by late May or early June. Use windbreak Yangshuo nutrient soil to grow strong seedlings. After planting, ensure the shed film is properly sealed for insulation. Maintain daytime temperatures between 28°C and 30°C, and use straw curtains at night to keep the bed temperature above 18°C. Once the first true leaf appears, gradually increase warmth to avoid heat damage. When the plants have four true leaves, perform hardening off to strengthen them.
**Timely Ditch Preparation and Fertilization**
Create high-yield ditches with a spacing of 45 to 3.8 meters, digging trenches 45 cm deep and 1 meter wide. After the Spring Festival, fill the ditches with composted manure (3,000–4,000 kg per acre), 15 kg of ammonium phosphate, and 10 kg of potassium sulfate. Adding 3,000 kg of furnace ash improves soil aeration. After filling, water the ditches, let the soil settle, and form two ridges, each 45 cm wide and 12 cm high, with 50 cm between them. During planting, place 3 kg of urea and 3 kg of diammonium phosphate per acre in the ridge top before placing seedlings and covering with mulch. Insert bamboo arches, cover with plastic film, and maintain 700–800 seedlings per acre.
**Shed Temperature Management**
After planting, cover the shed and provide insulation at night. During the day, maintain a temperature of around 30°C and ventilate when necessary. From late April, increase ventilation, and by mid-May, you can remove the shed film entirely.
**Leaf Growth Regulation**
Use triple vine pruning: allow the main vine to grow, then select two strong side vines at the base while removing all others. Control watering and fertilization before and after female flower opening to slow leaf growth and promote flowering and fruit setting. After the first harvest, apply quick-release fertilizer to encourage the second crop.
**Artificial Pollination for High-Quality Watermelons**
Pollinate the second female flower on the main vine between 7–9 am, and remove other female flowers. In the late stage of the first melon, choose one strong female flower to leave two fruits on the side vine. Ensure proper drainage and support to prevent waterlogging and improve fruit quality.
**Scientific Harvesting**
Harvest watermelons when they are fully mature, as this is when their sugar content is highest and quality is best. Avoid using ripening agents and do not pick unripe fruits to ensure optimal taste and marketability.
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