Detailed Explanation of the Key Technical Points for Bed-Frame Cultivation of Straw Mushroom
1 Cultivation Time
The time for bed-frame cultivation of straw mushroom should be chosen in seasons when the daily average temperature reaches above 25°C. This is because the growth and development of straw mushroom require the room temperature of the mushroom house to be kept above 27°C, and sharp rises or drops in temperature must be strictly avoided to prevent the young mushroom buds from shriveling and dying. According to several years of trials, the sowing period in this county can generally be arranged from early May to early September (if the room temperature is slightly low in May, a gasoline drum can be used for heating).
2 Structure and Requirements of the Mushroom House
Ordinary slate-roofed mushroom houses or general tile-roofed mushroom houses require internal sealing with plastic film or thick paper. Requirements: (1) Doors and windows can be sealed tightly; (2) There is a light intensity of 538 lux (that is, a light level in the mushroom house sufficient to read a newspaper normally); (3) The layer spacing of the bed frame is not less than 60 cm, and the width of the bed frame does not exceed 1 m; (4) When using a button mushroom house for cultivation, even greater attention should be paid to immediately removing the spent compost after button mushroom harvesting stops, washing the mushroom shelves clean with clear water, then disinfecting with limewash (use 0.5 kg of pure lime powder mixed with 50 kg of water), and scattering lime powder on the floor to prevent ants and other insect pests.
3 Selection of Spawn
Carefully selecting spawn and eliminating inferior spawn is one of the keys to the success or failure of straw mushroom cultivation. Generally, each square meter of cultivation area requires 2 bottles or 1 plastic bag of straw mushroom spawn. Straw mushroom spawn should be selected as young to middle-aged spawn with white or yellowish-white mycelium, translucent, with a small amount of chlamydospores, and with interwoven, thick and strong mycelium. Spawn with the following conditions must not be used. (1) Old spawn in which the mycelium gradually becomes sparse, the chlamydospores fill the culture medium in large amounts, and the upper layer of mycelium shrinks; (2) Spawn in which the mycelium is sparse and translucent, thin like spider silk, possibly caused by incomplete sterilization of the culture medium, with large amounts of Bacillus subtilis attached to the surface of the rice straw, so that the straw mushroom mycelium cannot absorb nutrients and has very few branches; (3) Spawn in which the mycelium gradually disappears and the bottle wall looks as if covered with a layer of powder, and the powder moves, generally spawn damaged by mites.
4 Cultivation Methods
4.1 Substrate Formula 100 kg dry rice straw, 10 kg dry cow dung, 5 kg wheat bran. The rice straw is first soaked in 1% limewater for 6-8 h, then taken out and drained. Straw mushroom is suitable for growing in a neutral or slightly alkaline substrate. When preparing the substrate, an appropriate amount of lime is usually added to adjust the pH to 9.0-10.0. After the substrate is fermented, the pH drops to 7.5-8.0, and this environment is favorable for straw mushroom growth.
4.2 Building the Substrate Heap The cow dung is moistened and crushed. On a concrete floor, spread a layer of rice straw, scatter a layer of the mixture of cow dung powder and wheat bran, then spread another layer of rice straw, then scatter another layer of the mixture of cow dung powder and wheat bran, and pile up layer by layer in this way until the heap is about 1.6 m high, 1.6-1.8 m wide, and the length is determined according to the amount of material used (generally 10-15 kg of material per square meter). After the heap is built, the heap temperature gradually rises. When the heap temperature rises above 65°C, turn the heap the next day (usually the heap is turned on the 4th day). The turning method is the same as for button mushroom.
4.3 Secondary Fermentation After turning the heap, ferment for another 2 d, then move it hot into the mushroom house, spread it on the bed frame, close the doors and windows, and introduce steam so that the temperature of the mushroom house reaches 60°C and is maintained for 6-8 h for pasteurization. After that, ventilate, and when the substrate temperature drops to 40°C, spawning can be carried out.
4.4 Spawning Use a method combining hole spawning and mixed spawning. The spawning rate is generally 1 bag of spawn per square meter. Then cover the surface of the substrate with a layer of fire-baked soil that has been temperature-adjusted and pasteurized, or rice husks, or fermented cow dung powder, close the doors and windows to keep warm for mycelial growth for 3-5 d, and maintain the mushroom house temperature at 32-35°C. During this period, if the substrate temperature reaches 40°C, the doors and windows must be opened for ventilation and cooling.
4.5 Keeping Warm for Mycelial Growth After spawning, seal the mushroom house. Use 1 gasoline drum for heating so that the room temperature of the mushroom house is controlled at 32-35°C and maintained for 4 d, promoting vigorous development of straw mushroom mycelium, covering the bed surface, and growing through to the bottom of the bed.
4.6 Primordium Induction On the 5th day after spawning, inspect the mycelial growth on the bed surface. If it has basically covered the surface, then in order to promote the formation of straw mushroom primordia, the following 4 measures must be taken: (1) Lower the temperature. Gradually lower the mushroom house from 34-36°C to 32±2°C. (2) Turn on lights (windows). Because the formation of straw mushroom primordia requires a certain amount of diffused light, supplementing the light intensity in the mushroom house to reach 538-645.6 lux can promote full fruiting on the mushroom bed. (3) Ventilate. The ventilation volume can be somewhat larger, but direct wind blowing in must be avoided, and straw curtains should be hung at the doors and windows. (4) Increase humidity. That is, properly add a small amount of water to the bed surface, and at the same time spray mist on the walls and passageways of the mushroom house to increase air humidity. The above 4 measures should be carried out simultaneously, and then maintain the air temperature at 32-35°C and the relative air humidity at 85%-90%.
4.7 Management and Harvesting Under normal conditions, 6-7 d after spawning, the mushroom buds begin to form knots. At this time, the mushroom house temperature should be maintained at 30-32°C, and mist spraying should be used continuously to keep the air humidity of the mushroom house at 85%-90%. Taking advantage of the higher outside air temperature at noon, carry out ventilation to reduce the carbon dioxide content in the mushroom house. The ventilation time should be controlled at 10-15 min, just enough to eliminate waste gas, and direct wind must be strictly prevented from blowing onto the bed surface. When cultivating straw mushroom in early spring or late autumn, special attention should be paid when the mushroom house temperature cannot be less than 27°C. If cold air causes a sharp temperature drop, heating should be carried out promptly (such as using electric lights, electric stoves, charcoal stoves, coal stoves, or a gasoline drum to heat and deliver hot steam) to supplement the suitable temperature required by straw mushroom. This is one of the key measures for the success or failure of straw mushroom cultivation and requires full attention. Under normal circumstances, a small amount of straw mushroom begins to be harvested on the 10th day after spawning. Egg-shaped mushrooms that have formed should be harvested promptly to increase the proportion of qualified mushrooms; they should be picked carefully, pressing the straw material down with the hand to avoid knocking over small mushrooms or breaking the mycelium, which would cause the small mushrooms to shrivel and die. After picking, use a small knife to cut off impurities at the base and place them in a clean plastic bucket. The first flush of straw mushroom can yield 50% of the total yield. Then clean the residual and dead mushrooms from the bed surface, keep the mushroom house temperature at 30-32°C and the air humidity at 85%-90%, and let it produce the 2nd and 3rd flushes. With good management, the 2nd flush can yield 30% of the total yield, and the 3rd flush can yield 20%. Several years of practice have proved that under relatively good growth conditions, every 50 kg of rice straw can yield 15 kg of mushrooms, and under ordinary conditions it can also yield 8-10 kg of mushrooms.
5 Fresh-Keeping and Processing Techniques
5.1 Fresh-Keeping Technique Harvested straw mushrooms continue to grow, which can lead to cap opening and reduced quality. At present, the fresh-keeping problem of straw mushroom has not yet been solved, and only short-term storage is possible. Harvested straw mushrooms should immediately be placed in a fresh-keeping warehouse at about 20°C for short-term storage of about 1 d, and the temperature in the warehouse should be as low as possible.
5.2 Processing Techniques There are many processing methods for straw mushroom, including drying, salting, and canning.
5.2.1 Drying of Straw Mushroom. Place the harvested fresh straw mushrooms on a dry bamboo sieve and sun-dry them in sunlight until dry, or bake them in a dryer. The baking process is 30 min at 60-64°C, then lower the temperature to 50°C and bake until dry. The quality of baked straw mushrooms is good.
5.2.2 Salting of Straw Mushroom. After fresh straw mushrooms are cleaned, put them into boiling water and cook until done but not mushy, take them out and put them into cold water to cool rapidly, then put them into 22 Baume brine for salting until the mushroom bodies sink in the brine.
5.2.3 Canning of Straw Mushroom. Put the prepared straw mushrooms into cans, vacuum-seal them, then sterilize and package them into food cans. Because canned food has both aseptic and sealed conditions, it is easier to store. At room temperature, it can be stored safely for more than half a year.