What are the management key points for soilless cultivation of bean sprouts?
Bean sprouts, also known as qiao ya, bean sprouts, ruyi cai, qia cai, silver sprouts, silver needles, silver seedlings, sprout hearts, soybean sprouts, and clear-water bean sprouts. Bean sprouts are also called sprout vegetables; they are edible “sprouts” grown from the seeds of various grains, legumes, and trees, and are also called “living vegetables.” The most popular sprout vegetables include: Chinese toon sprout vegetables, buckwheat sprout vegetables, alfalfa sprout vegetables, Sichuan pepper sprout vegetables, green black bean sprout vegetables, rosary pea sprout vegetables, sunflower seed sprout vegetables, radish sprout vegetables, dragon-beard bean sprout vegetables, peanut sprout vegetables, broad bean sprout vegetables, and more than 30 other varieties.
Traditional bean sprouts refer to soybean sprouts; later, new varieties such as mung bean sprouts, black bean sprouts, pea sprouts, and broad bean sprouts were gradually developed on the market. Although bean sprouts are all cold in nature and sweet in taste, their effects differ. Mung bean sprouts are easy to digest and have the effects of clearing heat and detoxifying, promoting urination and removing dampness, making them suitable for people with damp-heat stagnation, dry mouth and thirst, hot and reddish urine, constipation, and red swollen painful eyes. Soybean sprouts strengthen the spleen and nourish the liver, and have a relatively high vitamin B2 content; eating soybean sprouts appropriately in spring helps prevent angular cheilitis. Black bean sprouts nourish the kidneys and are rich in minerals such as calcium, phosphorus, iron, and potassium as well as various vitamins, in higher amounts than mung bean sprouts. Pea sprouts protect the liver and are rich in nutrients such as vitamin A, calcium, and phosphorus; broad bean sprouts strengthen the spleen and have the effects of supplementing iron, calcium, zinc, and more.
Management key points for soilless cultivation of bean sprouts
Seed selection: choose bean seeds that are mature, plump, have a high germination rate, and have strong sprouting vigor. Remove cracked beans, broken beans, tender immature beans, insect-damaged beans, and other debris. Beans that have been heated during storage and have become oily, or beans kept from the previous year, cannot be used for producing rootless bean sprouts; such beans not only have a low germination rate but may even fail to germinate. Moreover, they will rot and spoil during production.
Soaking beans: put the selected bean seeds into a [5] vat and fill it with water (tap water, well water, etc. are all fine), stir up and down, use a wire skimmer to remove floating beans and other debris, then rinse repeatedly with water until clean. After soaking for half an hour, pour them into a container. The drainage holes of the container must be plugged well with cattail-leaf strips, but not too tightly or too loosely; the standard is that water can drain smoothly while bean seeds will not leak out. A wooden barrel with a diameter of 64 cm and a height of 66 cm can hold 16.5 to 17.5 kg of bean seeds, generally filled to 1/3 of the container. After the bean seeds are put into the container, they should be sprinkled with water once more.
Watering: this is a key step in producing good bean sprouts. Although beans have a dormant period after maturing and being harvested, they are still respiring. This phenomenon becomes especially vigorous during germination. If the heat produced by respiration is not dissipated in time, the bean sprouts will rot and deteriorate, giving off a sour and foul odor. The frequency and amount of watering should be increased or decreased according to seasonal climate changes. In summer, when temperatures are high, water generally once every four hours, twice each time; in spring and autumn, when the climate is mild and suitable for bean sprout growth, water once every four to five hours; in winter, when the weather is cold and bean sprouts grow slowly, the room must be heated. Where conditions permit, the indoor temperature should be kept at 22 to 25°C, and watering should be done once every six hours, once each time. But use warm water, and control the water temperature well. Do not let it fluctuate up and down. If the water temperature is too high, bean sprouts will grow slowly, become curved, and turn grayish in color, commonly known as “lao kou”, and the growth period will be longer. Even more, prevent alternating hot and cold. In short, when mixing hot water, it must be even, with a feel that is mildly warm, and a temperature of 22°C is appropriate. Before watering, use a thermometer to measure the water temperature; do not estimate casually.
(Watering method: with one hand, hold the watering bucket and fill it with water from the vat, then slowly sprinkle it onto the palm of the other hand, just like watering flowers. Make the movements as slow as possible, and sprinkle it evenly and spread out; do not rush or pour carelessly, to prevent overturning or breaking the bean sprouts and affecting growth. Watering should be sufficient; while watering, let the water in the container flow out from the drainage holes, and also make the water in the container cover the bean sprouts.
1. Variety selection. Choose varieties with a high germination rate, strong disease resistance, no shriveled grains, high yield, less fiber, and relatively good quality, such as small-seeded peas, hemp peas, dragon-beard peas, and so on.
2. Seed soaking. Take seeds that have been dried in the sun and cleaned, first rinse them with clean water 2 to 3 times, and after washing them clean, stir and soak them in 55°C warm water for about 15 minutes, then soak the seeds in warm water for 6 to 8 hours.
3. Sowing. Clean the seedling tray in advance and spread the substrate. The specifications of the seedling tray are preferably 60 cm × 25 cm × 5 cm. For the growing substrate, use sterilized perlite, fine sand, non-woven fabric, and so on. First spread a layer of substrate, then evenly scatter a layer of the soaked seeds; the sowing amount per tray is 450 to 500 g, then scatter a thin layer of substrate to cover the seeds, then spray with 20°C warm water, and afterward stack the trays on the seedling rack, with each stack about 10 trays high. Cover the topmost seedling tray with a light-blocking and heat-preserving material, such as a wet cloth.
4. Management after the seedling trays are placed on the rack. After the seedling trays are placed on the rack, cover them with clean black plastic film, or place them in a dark room for cultivation, to promote the sprouts to grow in darkness. Every 4 to 6 hours, uncover the plastic film and spray with 20°C clean water once. While spraying water, check the germination condition and discard moldy and spoiled seeds. After 8 to 10 days, the sprouts can reach 15 to 16 cm in height, and the cotyledons have just unfolded. At that time, the light-blocking material should be removed immediately so they gradually adapt to a strong-light environment. After two days, the light-blocking material can be completely removed, allowing the sprouts to continue growing under natural light conditions and prompting the sprouts to change from yellow-green to deep green. Generally, after 12 to 15 days of cultivation, they can be harvested in time according to market demand, and can be sold as whole trays or neatly arranged and packed in plastic boxes or plastic bags for market sale.