Key Points of High-Yield Cultivation Techniques for Water Spinach in Spring
Water spinach, also called water convolvulus, swamp cabbage or vine vegetable, is a fast-growing leafy green vegetable that has been introduced and planted in more places in recent years. Its edible parts are the tender stems and leaves. It is rich in nutrients and high in calcium, with a calcium content more than ten times that of tomato, ranking first among leafy vegetables, and it also contains a relatively large amount of carotene. It can be used in cold dishes, stir-fries or soups, and has now become a common dish on ordinary people's tables and one of the specially requested vegetables in hotels and restaurants.
Water spinach's requirements for the environment
Water spinach likes a hot and humid environment. Seed germination requires above 15°C; during the initial stage of axillary bud germination of seed vines, the temperature must be kept above 30°C so that budding is rapid and uniform; the suitable temperature for vine and leaf growth is 25-30°C. The higher the temperature, the more vigorous the vine and leaf growth, and the shorter the picking interval. Water spinach can tolerate high temperatures of 35-40°C; below 15°C, vine and leaf growth is slow; below 10°C, vine and leaf growth stops. It is not tolerant of frost, and stems and leaves die as soon as they are exposed to frost. The storage temperature for seed vines in cellars should be kept at 10-15°C, with relatively high humidity, otherwise the seed vines are likely to freeze to death or dry out.
Water spinach likes relatively high air humidity and moist soil. If the environment is too dry, the vines produce more fiber, become coarse and old and unfit to eat, greatly reducing yield and quality. Water spinach likes sufficient light, but it also adapts fairly well to dense planting. Water spinach is not strict about soil conditions, but because it likes fertilizer and water, soil that is relatively clayey and has strong water- and fertilizer-holding capacity is still best. The leaf tips of water spinach grow abundantly and rapidly, so it has a high fertilizer requirement, strong fertilizer tolerance, and an especially large demand for nitrogen fertilizer.
How can water spinach be cultivated in spring for high yield?
1. Land preparation and bed making
Water spinach grows quickly and has strong branching ability, so it needs a sufficient supply of water and fertilizer. Base fertilizer must be applied abundantly. Generally, 500-1000 kg of decomposed organic fertilizer and 100 kg of plant ash are applied per mu, spread evenly, and the soil is plowed to a depth of about 20 cm so that the manure and soil are fully mixed, then beds are made. The beds are 20 cm high and 1.0-1.5 m wide (including ditches). Note that the base fertilizer should be applied several days in advance to prevent manure fermentation caused by film-mulched seedling raising from burning the seedlings.
2. Seed soaking and sprouting
Water spinach seeds have a thick, hard seed coat and absorb water slowly. If sown directly, they germinate slowly because of low temperature, and if there is prolonged low-temperature rainy weather, the seeds may rot, so sprouting should be promoted. The seeds can be soaked in warm water at 40-50°C for 30 minutes, then soaked in clean water for 16-20 hours, taken out, washed, wrapped in gauze, and kept at 30°C for sprouting. During sprouting, keep them moist and rinse the seeds once a day with clean water. When 50-60% of the seeds have broken white, they can be sown.
3. Sowing at the right time
The suitable sowing period for water spinach is mid-to-late March. It can be broadcast, drilled or dibbled. For broadcast sowing, the seeding rate is about 10-15 kg per mu. After broadcast sowing, cover with fine soil about 1 cm thick; for drilling, a shallow furrow 2-3 cm deep can be drawn across the bed surface, with furrow spacing of 15-20 cm. First water thoroughly, then sow the seeds evenly in the furrows, then cover with fine soil. The seeding rate per mu is 1.5-2.0 kg; for dibbling, with row spacing of 30-35 cm and hole spacing of 15-20 cm, sow 3-4 seeds per hole, then water immediately after sowing and cover with soil. After covering with soil, cover the bed surface with film and add straw mats, etc., to raise soil temperature. From sowing to emergence, keep the soil moist. After emergence, the covering can be uncovered. When the seedlings grow to 15-18 cm, they can be transplanted, or thinned and harvested. During the growth period, about 15 cm shoot tips can also be picked for cutting propagation. When soil moisture is suitable, the cuttings will quickly grow adventitious roots and send out new shoots. For water planting, vine seedling raising is mostly used. Use seed vines selected the previous year, promote sprouting, insert them into the seedling bed, and when the seedlings are 30 cm high, press the vines to encourage adventitious roots to form downward at the nodes and lateral branches to grow upward, then use the successively produced lateral branches for cutting and transplanting.
4. Timely planting
Water spinach is not strict about soil conditions and has wide adaptability. It can be planted in dry land, paddy fields and field corners by ditches, but for dry planting it is best to choose low-lying, moist and fertile clay loam, and it can be planted with row spacing of 30-35 cm and hole spacing of 15-20 cm. For water planting, it is best to choose muddy field plots with convenient irrigation and drainage, shade facing and sun facing, and a relatively shallow water layer, with a plant and row spacing of 20 cm being best. When transplanting, the leaves should be exposed above the water surface.
5. Field management
Water spinach is a light-loving crop. During the growth period, debris on the film should be removed in time to keep sufficient light in the greenhouse, which is beneficial to the growth of water spinach. When water spinach is cultivated in greenhouses in spring, because the temperature is low, humidity is high, and low-temperature rainy weather lasts a long time, growth is extremely unfavorable, so heat preservation and cold protection are the key to ensuring high yield of water spinach. After sowing, the greenhouse should be sealed in time to ensure that the temperature inside is above 10°C. On sunny days with sufficient sunlight and relatively high temperature, ventilation should be carried out in time to cool and dehumidify, trying to avoid the temperature inside the greenhouse rising above 35°C, preventing plant diseases and keeping the plants growing vigorously to increase yield. When humidity in the greenhouse is high, the film at both ends or around the sides must be uncovered in time for ventilation and dehumidification. During the growth period, cultivate and weed in time; after the rows close, weeding and cultivation are not necessary. For water-planted fields, drain the water and dry the field to raise soil temperature.
6. Fertilizer and water management
Water spinach is a crop harvested multiple times, so in addition to applying sufficient base fertilizer, multiple split topdressings must be carried out to obtain high yield. Topdressing can be done in combination with watering. At the seedling stage, dilute human urine and manure at 10%-15% can be used, with 1000 kg per mu; when the seedlings grow 3-4 true leaves, apply 15-20 kg of compound fertilizer and 2-4 kg of urea per mu as a mixed application; during the harvest period, apply 5-8 kg of compound fertilizer per mu after each harvest. Water spinach is a leafy vegetable crop and has a large water requirement, so a sufficient water supply must be ensured, and it should be watered frequently to keep the soil surface moist.
7. Pest and disease control
Adhere to the principle of "prevention first, integrated control" and adopt comprehensive agricultural, physical and chemical prevention and control measures to prevent and control the occurrence of pests and diseases. Remove diseased residues, weeds and dead leaves from the field in time, strengthen temperature and humidity management in the field, and use physical measures such as yellow sticky boards and insect-proof nets to control pests and diseases. The main diseases at the seedling stage of water spinach are damping-off and stem rot, which are caused by relatively low temperature and excessive relative humidity. Reducing humidity can reduce the occurrence of diseases, and chlorothalonil or thiophanate-methyl can be used for control; diseases during the growth period include white rust, brown spot and mosaic disease. White rust can be controlled with 1:1:200 Bordeaux mixture, or 0.2 Baume lime sulfur mixture, or 50% carbendazim wettable powder 500 times liquid, or 65% zineb wettable powder 500 times liquid; brown spot can be controlled with 50% metalaxyl-copper wettable powder 600-700 times liquid, or Luiheng No. 1; mosaic disease can be controlled with Virus A or Zhibingling. The main insect pests include cabbage caterpillars, tobacco cutworm larvae, mites and red spiders, which can be controlled with 50% phoxim emulsifiable concentrate, or 80% dichlorvos emulsifiable concentrate, or 20% fenvalerate emulsifiable concentrate 8000 times liquid.
8. Harvesting at the right time
Generally 35-45 days after sowing, when the water spinach plants are 30-40 cm high, they can be harvested. If harvested all at once, they can be harvested for market when the plant height is 20-35 cm. If harvested multiple times, thin the seedlings when the plant height is 10-15 cm, and the thinned seedlings can be sold; when the plant height is 15-20 cm, final thinning can be done, and the thinned plants can be pulled for market together with final thinning, while the remaining seedlings can be harvested multiple times. When the seedlings are about 35 cm high, carry out the first picking, leaving 2 stem nodes on the stem. Thereafter, for the second picking leave the second stem node remaining on the stem, and for the third picking leave the first stem node remaining at the stem base, so as to promote new sprouting at the stem base and keep the stems and vines picked later thick and strong. When picking, pinching by hand is more suitable; if knives, scissors or other iron tools are used, the cut area is prone to rust death. If there are too many branches, too dense or too thin, thin them out by pruning. In the early harvest period and late growth period, harvest once every 7-10 days; in the peak growth period, harvest once every 5-7 days. Generally, the yield per mu for a one-time harvest can reach more than 15 kg, and the yield per mu for multiple harvests can reach more than 5000 kg.