Detailed Explanation of Key Techniques for Winter Plastic Greenhouse Cultivation of Water Spinach
Water spinach is widely cultivated throughout our province and is a major green leafy vegetable that fills the gap in summer and autumn. Water spinach likes high temperatures and high humidity, has strong heat tolerance, and is not tolerant of frost; when frost occurs, the stems and leaves wither and die. The optimum growing temperature is 25-30°C, and growth stops below 10°C. Therefore, plastic greenhouses should be used for off-season cultivation in winter. 1. Varieties...
Water spinach is widely cultivated throughout our province and is a major green leafy vegetable that fills the gap in summer and autumn. Water spinach likes high temperatures and high humidity, has strong heat tolerance, and is not tolerant of frost; when frost occurs, the stems and leaves wither and die. The optimum growing temperature is 25-30°C, and growth stops below 10°C. Therefore, plastic greenhouses should be used for off-season cultivation in winter.
1. Variety selection: The varieties suitable for cultivation in our province include Da Ji Huang, Da Gu Qing, Jian Ye, Si Yong, Da Ji Qing, and others.
2. Cultivation season: Greenhouse cultivation can basically achieve year-round production and year-round supply. In order to obtain higher economic benefits, sowing should be arranged from October to December, with harvesting from December to March of the following year.
3. Land preparation and fertilization: Water spinach grows quickly and has strong branching ability, so it requires more fertilizer and water. When planting, sufficient base fertilizer should be applied. Generally, 1500-2000 kg of decomposed organic fertilizer and 100 kg of plant ash are applied per mu, fully mixed with the soil, and raised into beds 20 cm high and 130-150 cm wide (including trenches).
4. Seed soaking and germination: The seed coat of water spinach is thick and hard. If sown directly, germination will be slow due to low temperature, and prolonged low-temperature rainy weather can cause the seeds to rot. Therefore, it is best to sow after germination. Soak the seeds in warm water at about 30°C for 18-20 hours, then wrap them in gauze and place them at 30°C for germination. When 50%-60% of the seeds show white sprouts, they can be sown.
5. Sowing: Water spinach can be broadcast sown or drilled. The seeding rate is 15-20 kg per mu. After broadcast sowing, cover with fine soil about 1 cm thick. For drilling, dig shallow trenches 2-3 cm deep across the bed surface every 15 cm, evenly scatter the seeds into the shallow trenches, then cover with fine soil, then cover the bed surface with a shade net, water, and uncover the shade net after the seedlings emerge.
6. Greenhouse management
1. Temperature and humidity management: During greenhouse cultivation in winter, the temperature is low, the humidity is high, and prolonged low-temperature rainy weather lasts a long time, which is extremely unfavorable to the growth of heat-loving water spinach. Therefore, heat preservation and cold protection are the key to off-season cultivation of water spinach. After sowing, when there is sufficient sunlight and the temperature is relatively high, ventilation should be strengthened to remove moisture, and the temperature inside the greenhouse should be kept from exceeding 35°C as much as possible to prevent plant diseases, maintain vigorous growth, and increase yield. If low-temperature weather occurs after sowing, the greenhouse should be sealed promptly, and the temperature inside should be maintained above 10°C, otherwise frost damage may occur. The relative air humidity inside the greenhouse may reach 100% under higher temperatures and on rainy days. At this time, the films at both ends or around the greenhouse must be uncovered promptly for ventilation.
2. Fertilizer and water management: Water spinach is a crop harvested multiple times. Therefore, in addition to applying sufficient base fertilizer, multiple topdressings are necessary to obtain high yield. During the seedling stage, 10%-15% diluted human manure and urine can be used for drenching, at 1000-1500 kg per mu. When the seedlings have 3-4 true leaves, apply a mixture of 15-20 kg of compound fertilizer and 2-4 kg of urea. During the harvest period, apply topdressing once after each harvest, with 5-8 kg of compound fertilizer per mu. Water spinach has a relatively large water requirement, so it should be watered frequently to keep the bed surface moist.
3. Pest and disease control: The main diseases of greenhouse-cultivated water spinach are damping-off and stem rot during the seedling stage, which are caused by low temperature and excessive relative humidity. Reducing humidity can alleviate the occurrence of the diseases. At the same time, spraying with 700 times Ridomil or 800 times Kameitong can be used for control. The main insect pests are mites and red spiders, which can be controlled with 1000 times Kelmante or 1500 times Kasike.
7. Harvesting: Generally 35-45 days after sowing, when the water spinach plants have grown to 35 cm high, they should be harvested promptly.