Scientific cultivation techniques for black fungus (wood ear mushroom), the latest high-yield cultivation methods
With the improvement of people's living standards, black fungus (wood ear mushroom) has become a edible fungus loved by consumers. Black fungus is tender in texture, smooth and crisp in taste, and rich in nutrients, with high edible and medicinal value. Its protein content is second only to meat, eggs, fish, and beans, higher than any other vegetable. Therefore, people often compare black fungus to a “meat among vegetarian foods” nutritional food. Below, Professor Wang Li'an from the College of Life Sciences, Hebei Normal University, will give everyone a detailed introduction to the artificial high-yield cultivation techniques for black fungus.
Main technical model for artificial cultivation of black fungus: using broadleaf tree sawdust or cottonseed hulls as raw materials, adopting the sterilized substrate bag cultivation model. In this model, the spawn can be solid spawn or liquid spawn; fruiting can be carried out using shade sheds, open-field bag placement in fields, shelf bag placement, or hanging bags, etc.
Nutrients required for normal growth of black fungus
The nutrients required during growth are mainly carbohydrates and nitrogen-containing organic matter, and a small amount of inorganic salts is also needed. In artificial cultivation, broadleaf tree sawdust, cottonseed hulls, corn cobs, sugarcane bagasse, etc. are generally used as the main substrate. Nitrogen-containing substances that can be utilized by black fungus include proteins, amino acids, urea, etc. During cultivation, wheat bran, cake fertilizer, etc. are generally added as nitrogen sources.
Inorganic salts mainly include: calcium, phosphorus, potassium, iron, magnesium, etc. They are important components of proteins and enzymes in the fungus body. The required amount is not large, but they are indispensable. Generally, sawdust can provide them, and during cultivation gypsum, potassium dihydrogen phosphate, etc. can be added to ensure this.
Temperature requirements of black fungus
Black fungus belongs to the medium-temperature type of fungi. It has the characteristics of being cold-tolerant and afraid of heat, so black fungus in the south is not as black in color, as large in fruiting body, or as thick in flesh as that in the north.
Black fungus mycelium can grow and develop between 5-35°C, but 22-28°C is the most suitable. Above 28°C, although the growth speed is fast, the mycelium is fine and easily ages; below 10°C growth is inhibited, but it will not freeze to death even in an environment of -30°C.
The fruiting bodies of black fungus can form and grow between 15-30°C, but those grown between 22-25°C have large ear pieces, thick flesh, and good quality. Fungus grown above 28°C has slightly thinner flesh, pale yellow color, and poor quality. Although fungus grown between 15-20°C has thick flesh, black color, and good quality, it grows slowly, the production cycle is long, and yield is affected. Below 15°C it is difficult to form fruiting bodies.
Humidity requirements of black fungus
The humidity requirements of black fungus are shown in two aspects:
First, the moisture content of the substrate. During the spawn-running stage, the moisture content of the substrate is required to be 60%-65%; during the fruiting body formation stage, the optimal moisture content in the substrate is 70%-75%.
Second, air relative humidity. During the spawn-running stage, the air relative humidity in the spawn-running room is required to be about 70%; during the fruiting stage, the air relative humidity is required to be 85%-95%. Because the ear pieces of black fungus are gelatinous, they easily absorb moisture from the air and swell, and only after absorbing water and swelling can they grow and develop. When the air relative humidity is below 80%, ear piece growth is slow; below 70%, ear pieces are not easy to form. But if the air relative humidity exceeds 95%, it is also unfavorable for the growth and development of ear pieces, and diseases are likely to occur.
Light requirements of black fungus
Black fungus belongs to the light-loving type of fungi, but mycelial growth does not need light; light intensity instead inhibits mycelial growth, so during the spawn-running stage it should be kept dark. Black fungus fruiting body formation requires light. In a completely dark environment, black fungus is not easy to form fruiting bodies; insufficient light causes deformed fruiting bodies. Ear buds can only grow robust ear pieces under a certain amount of direct sunlight. Fungus grown after direct light irradiation is thick. In ear yards without direct light, the fungus grown has thin flesh, pale color, lacks elasticity, and appears unhealthy. Therefore, black fungus is one of the most light-loving species among artificially cultivated edible fungi. But note that although black fungus has a relatively strong tolerance for direct light, appropriate humidity must be provided at the same time; otherwise the ear pieces will shrink, dry out, stop growing, and yield will be affected.
Ventilation and pH requirements during the cultivation of black fungus
Black fungus is an aerobic fungus. Both the spawn-running and fruiting stages require good ventilation conditions to ensure sufficient oxygen and discharge CO2. If ventilation is poor during the spawn-running stage, the spawn bags are very likely to suffer mold contamination; if ventilation is poor during the fruiting body growth stage and the carbon dioxide concentration is relatively high, primordia are not easy to differentiate, ear pieces cannot stretch normally, and development is inhibited. Therefore, during the cultivation of black fungus, the air in the spawn-running room or ear yard should often be kept circulating to ensure the needs of black fungus growth and development.
Black fungus is suitable for living in a slightly acidic environment. The pH value of the substrate is best at 5.5-6.5. When mixing the substrate, the pH value of the substrate can first be adjusted to the range of 7-8 with quicklime, and after sterilization the required pH can be reached.
Common formulas for artificial cultivation of black fungus
(1) Broadleaf tree sawdust 78%, wheat bran or fine rice bran 20%, gypsum powder 1%, white sugar or brown sugar 1%.
(2) Corn cob powder 73%, cottonseed hulls 20%, wheat bran 5%, white sugar or brown sugar 1%, gypsum 1%.
(3) Broadleaf tree sawdust 76%, rice bran 10%, wheat bran 10%, soybean powder 2%, white sugar or brown sugar 1%, gypsum 1%.
(4) Cottonseed hulls 93%, wheat bran 5%, gypsum 1%, white sugar or brown sugar 1%.
Note: the substrate should use fresh, dry raw materials free of mildew. For sawdust, use broadleaf tree species; for corn cobs, it is best to first expose them to sunlight for 1-2 days, then crush them with a grinder into particles the size of soybean grains to corn grains. Do not crush them into bran form, so as not to affect the aeration of the substrate.
How should the cultivation season of black fungus be arranged
Generally speaking, the normal spawn-running period is 45-50 days, the spawn-resting period is 10-15 days, the bud-forcing period is 7-10 days, and the harvest period is 45-60 days.
In seasonal arrangement, the fruiting period should avoid high temperatures above 30°C and low temperatures below 18°C as much as possible. According to the temperature requirements of black fungus, in southern China, cultivation can generally be carried out in spring and autumn. For spring cultivation, bags are made and inoculated in February-March, and fruiting occurs in April-May; for autumn cultivation, bags are made and inoculated in August-September, and fruiting occurs in October-November.
In northern China, cultivation is generally chosen in spring and summer, with bags made from March-May and fruiting from May-September. In North China, two batches can be produced in 1 year. For the first batch, cultivation bags are produced in mid-February, they can be put into the ground to force ears in mid-to-late April, and fruiting ends in early-to-mid July. For the second batch, spawn bags are produced in mid-to-late May, they can be put into the ground to force ears in early-to-mid August, and fruiting ends in early November.
For the spawn production time of black fungus, based on the production time of cultivation bags, secondary spawn should be advanced by about 65 days accordingly, and tertiary spawn should be advanced by about 30 days accordingly. At the same time, different regions should also appropriately advance or postpone the bag-making and inoculation times.
Process flow and precautions for artificial cultivation of black fungus
Mixing substrate → Bagging → Sterilization → Inoculation → Spawn-running management → Bud forcing → Fruiting management → Picking → Sun-drying.
When mixing the substrate, pay attention to the following aspects: First, strictly weigh and mix materials according to the requirements of the cultivation formula. Do not arbitrarily add substances of unknown composition to the substrate. Second, mix dry first, then wet, and strive for uniformity. This can be done manually or with a substrate mixer. Third, control the moisture content in the substrate at about 60%, that is, the ratio of dry material to water is 1:1.1-1.3. Before bagging, check the moisture content by hand: grip the substrate tightly with the palm, if there is water between the fingers but it does not drip, and the substrate in the palm can form a ball, this is the appropriate moisture content; if water drips down in strings, it indicates it is too wet. Generally, it is better to be dry than wet. Too high moisture content will not only lead to slow spawn running, but also easily contaminate with miscellaneous fungi. Fourth, the pH value should be appropriate, measurable with pH test paper, and controlled at about 7. Finally, after mixing the substrate, bag and sterilize promptly to prevent spoilage of the substrate.
Bagging generally uses mechanical bagging; for small amounts, manual bagging can be used. Commonly used are 17cm×33cm low-pressure polyethylene short bags or 12cm×45cm long bags. Whether mechanical bagging or manual bagging, the following must be achieved: fast, moderate tightness, sealed bag openings, and handle gently.
Sterilization precautions:
Sterilization often uses the normal-pressure sterilization method. When sterilizing 17cm×33cm short spawn bags, it is best to place them in iron baskets or on shelves in the steamer; when sterilizing 12cm×45cm long spawn bags, place the substrate bags flat along the long direction, arranged in overlapping “#” shape, with row spacing of 3 cm, to facilitate internal air circulation. Then seal the pot tightly with plastic sheeting and cotton quilts, and after the temperature inside the spawn bags reaches 100°C, maintain it for more than 12-16 hours. After sterilization, when the temperature of the spawn bags drops below 60°C, take them out while hot, and send the spawn bags into the inoculation room for cooling.
Inoculation precautions:
When the temperature of the substrate in the bags drops below 30°C, inoculation can be carried out.
Inoculation must be done aseptically, completed in an inoculation room or inoculation box.
The inoculation procedure for short spawn bags is: place the cooled spawn bags into a sterile inoculation box; wipe and disinfect the outer wall of the spawn bottle with 75% alcohol and also place it into the inoculation box. In the sterile area with the alcohol lamp lit, face the bottle mouth toward the bag mouth, and evenly sprinkle the spawn onto the substrate surface in the bag, forming a thin layer. In this way, black fungus mycelium germinates quickly and preemptively occupies the substrate surface to inhibit contamination by miscellaneous fungi. If a conical plastic insertion rod was used when bagging, the plastic insertion rod can be pulled out, and the spawn can be inoculated into the hole left by the insertion rod. In this way, the spawn grows from the inside outward, and spawn running will be faster. Generally, each bottle of spawn can inoculate about 30 bags.
For long spawn bags, the hole-punching inoculation method is used, that is, in a sterile inoculation room, punch holes with a diameter of 1.2 cm and a depth of 2 cm on one side of the spawn bag, quickly inoculate the spawn blocks, and then immediately seal the openings with adhesive tape. The requirements are fast and accurate hole punching, inoculation, and sealing.
Technical points for spawn-running management:
After inoculation, short spawn bags should be placed on disinfected cultivation shelves for spawn running. The height between each layer of the cultivation shelf is about 35cm. In the early cultivation period, the bags should be placed upright and neatly, with appropriate spacing between bags. After the mycelium extends into the substrate, the bag bottoms can be placed facing each other, mouths facing outward, laid horizontally in 2 rows, and stacked 4 rows vertically. In cultivation rooms without shelves, spawn bags can be arranged into spawn walls for spawn running, generally 6-8 layers; walkways are left between spawn walls. When running spawn in long spawn bags, arrange the cultivation bags in a “#” shape, about 10 layers high. In the initial stage, four spawn bags per layer, with appropriate spacing between each stack. As the temperature rises, this can be changed to three per layer or two per layer.
In the early spawn-running stage, that is, within 15 days after inoculation, the temperature of the cultivation room should be appropriately lower, maintained at 20°C-22°C, so that the newly inoculated mycelium slowly recovers growth. The mycelium is then thick and vigorous, and contamination by miscellaneous fungi can be reduced. In the middle spawn-running stage, that is, 15 days after inoculation, black fungus mycelium growth is already dominant, so raise the temperature to about 25°C to speed up spawn running. In the late spawn-running stage, when the mycelium is almost full, that is, within the final 10 days before cultivation ends, lower the temperature to 18°C-22°C. Mycelium grown at a relatively low temperature is robust, and nutrient decomposition and absorption are sufficient. Spawn bags cultivated in this way fruit early, differentiate quickly, have strong disease resistance, and have high yield.
During the spawn-running period, the temperature inside the spawn bags must always be controlled below 32°C. Temperature measurement is based on the second layer from the top and the bottom layer. The air relative humidity of the cultivation room is generally maintained between 55%-65%. Black fungus does not need light during the mycelial cultivation stage. The windows and ventilation holes of the cultivation room should be shaded to keep indoor light close to darkness. The cultivation room should be ventilated for 20-30 minutes every day. Ensure sufficient oxygen to maintain normal metabolism of black fungus mycelium. In the later stage, increase ventilation time and frequency even more, and keep the air in the cultivation room fresh.
Precautions during spawn-running cultivation
(1) The cultivation room must be hygienic and dry, and air humidity must not be greater than 70%. (2) The cultivation room should be disinfected before bags are brought in. Aerosol disinfection boxes can be used for sterilization treatment, and at the same time a sprayer can be used to spray carbendazim or pyrethroid insecticides for sterilization and pest removal. It is best to spread a layer of quicklime on the ground, and more can be spread at the doorway. (3) The cultivation room should be protected from light. (4) Check spawn-running conditions regularly. Spawn bags that have not successfully inoculated and are not contaminated can be re-inoculated; for locally contaminated spawn bags, local injection of carbendazim or limewater can be used to control continued infection; for seriously infected spawn bags, remove them promptly, and the removed spawn bags should be sterilized again by re-sterilization to prevent the spread of miscellaneous fungi.
How to make beds for well-run spawn bags
Black fungus fruiting can be carried out using shade sheds, open-field bag placement in fields, shelf bag placement, or hanging bags, etc. Generally, the south mostly uses shade sheds. The north mostly uses the open-field bag placement method. Using the latter requires first making beds for the spawn bags. Choose flat terrain, close to a water source, with good drainage, and use open space in front of or behind the house to make fungus beds. Avoid air vents as much as possible, and stay away from livestock farms. Clear away garbage around the fungus beds. The fungus bed is 5cm high and 90cm wide, with unlimited length. Drainage ditches are left between beds. After the beds are made, water the bed surface heavily once, then spray carbendazim or pyrethroid insecticides for sterilization and pest removal treatment.
Technical points for bud-forcing management
Transport the cultivated spawn bags to the fungus bed site. Spawn bags with local contamination by miscellaneous fungi should be placed separately and opened last. Handle gently during transport.
Disinfect the entire spawn bag with 1% quicklime water or 0.1% potassium permanganate solution, then remove and drain. Use a punching machine to make V-shaped cuts on the surface of the spawn bag. The diagonal line of the V-shaped cut is 1.5cm long and the depth is 0.5cm. Short spawn bags have about 20 cuts, and long spawn bags have about 40 cuts.
After punching, place the spawn bags upright on the fungus bed to force buds. Leave a distance of 3cm between bags. When arranging, do not lay plastic film on the ground. If the ground is dry, spray some bottom water; if the ground is relatively moist, place the bags directly. After arrangement is complete, cover with plastic film, and cover the film with straw curtains. After that, enter the bud-forcing period management.
Technical points for management during the fruiting body differentiation stage
The fruiting body differentiation period of black fungus refers to the period when the ear base forms a coral-like shape and grows to the size of a peach pit, and small ear pieces begin to extend from above. After the ear base emerges, the ear base is exposed to the air, and the relative humidity in the air should not be lower than 90%, keeping the surface of the fungus primordium from drying out. If humidity is insufficient, the ear base easily loses water and becomes rigid, affecting ear piece differentiation. To maintain humidity, spray mist water on the spawn bags, using the standard that ear pieces are moist but edges do not curl. Directly spraying water on ear pieces should be minimized to avoid causing rotten ears or slipping ears. Ventilate every evening until the ear buds grow to about 1 cm, then begin bed separation management.
Before bed separation, lay a layer of plastic film on the ground. Spawn bags must be handled gently and placed upright. Long spawn bags should be cut open from the middle. Place 20 bags per square meter, with 10cm between bags, to prevent the fungus from sticking together as it grows and to avoid affecting air circulation.
Technical points for management during the fruiting body growth stage
When the ear pieces unfold to about 1 cm, they enter the fruiting body growth stage. During this period, increase the air relative humidity to between 90-95%, and strengthen ventilation. In this period, water spraying management is the most critical link. Use clear, unpolluted river water or well water; use dedicated spraying facilities such as micro-sprinkler nozzles for irrigation. Generally, the twice-daily watering method is used, from 5 a.m. to 7 a.m. and from 5 p.m. to 7 p.m. For black fungus moisture management, pay attention to maintaining the management technique of “alternating dry and wet, dry thoroughly when dry, wet thoroughly when wet, clearly distinct dry and wet.” During management, keep the edges of the ear pieces always curled inward, control ear piece expansion, and make them thicker. If the ear base is contaminated, it can be directly rinsed with clean water. When the temperature is above 25°C, stop spraying water.
Precautions for picking and sun-drying black fungus
When white spores appear on the back of the ear pieces and they reach eight-tenths maturity, harvest promptly. Stop spraying water 1-2 days before harvest. If you wait until the ear pieces elongate or curl upward before picking, quality and yield will be affected. When harvesting, cut at the ear base with a blade, and try not to carry substrate, so as to keep the ear pieces clean. Do not hold the ear pieces with your hands and twist them off directly.
When sun-drying ears, place ear pieces on top and ear bases below. For large clusters, tear the ear pieces apart into single pieces when drying. When sun-drying ears, use a mesh support to allow air circulation above and below. During sun-drying, turn them as little as possible and dry them completely in one go.