Key Technical Points for High-Efficiency Cultivation of Straw Mushrooms in Winter

Straw mushrooms (Volvariella volvacea) are a high-temperature, high-humidity type of fungus, suited to growing in an environment of constant temperature and stable humidity. The suitable growing temperature for straw mushrooms is 23-25°C, and the relative air humidity is 85%-95%. Therefore, to move the high-temperature straw mushroom to cultivation in the lower temperatures of winter, it must be grown in greenhouses with good insulation capacity, which increases cost inputs such as heating. Moreover, straw mushrooms produced in winter sell for 2 times the price of those from conventional summer cultivation, so appropriate adjustments should be made in aspects such as the culture material formula and cultivation management, in order to increase the input-output ratio and improve economic returns. The main techniques for winter cultivation of straw mushrooms are introduced as follows.

1. Select a suitable culture material formula and build piles for fermentation. For off-season cultivation of straw mushrooms, a single straw formula with few nutrients and low yield cannot be used; instead, a formula rich in nutrients and high in biological efficiency should be selected. In production, the formula mostly used is 68% cottonseed hulls, 20% rice straw, 1% urea, 6% lime, 3% calcium carbonate, 2% plant ash, or 77% waste cotton, 10% rice straw, 5% wheat bran, 8% lime. Using the two-stage fermentation method, first sun-dry the cottonseed hulls for 3-4 days, adjust with lime water until the moisture content of the material is 70%-75% and the pH value is 7-8, pile outdoors for 3 days, then move the material indoors, keep the room temperature at 60°C for about 2 days, or maintain the material temperature at 70°C for 10 hours.

2. Management before spawning and fruiting

After the culture material fermentation is finished, adjust the moisture content to 65% and the pH value to about 9. When the material temperature drops to 35°C, spawning can begin. The strip-laying broadcast spawning method can be used: divide the bed width of 80 cm into 5 equal parts, each strip 16 cm wide, fill the middle strip with fertile soil, and fill the two sides with material, using 10 kg of material per sq m. After the material is laid, press it lightly, scatter the spawn on the surface of the material, with the spawn amount being 4%-6% of the material weight, then scatter a layer of culture material over the spawn, and attach 5-6 cm of fertile soil along the outer sides of the two culture material strips. Close the mushroom shed so that the shed temperature reaches 30-35°C, and do not open doors or windows for 3 days to maintain high temperature and high humidity, which favors mycelial germination. After that, ventilate for about 20-30 minutes each day. After 4-5 days, when the mycelium has colonized 2/3 of the material, a small amount of water can be sprayed to encourage the mycelium to fully colonize the material. After 6 days, when the mycelium has grown through the material, water should be adjusted to a sufficient level, and ventilation and light exposure should be strengthened to promote fruiting body formation. After 8 days, the mycelium begins to knot and mushroom buds appear. At this time, the surface of the material should be kept appropriately dry, to increase mushroom formation and reduce dead mushrooms.

3. Strengthen management during the fruiting period and harvest in time. About 10 days after spawning, dense small white dot-shaped mushroom buds can be seen appearing and gradually growing larger, and the first flush of mushrooms can be harvested at 13-15 days; the yield of the first flush accounts for 60%-70% of the total yield. Therefore, management of temperature, humidity, air and light should be strengthened. When the mushroom buds form, strengthen ventilation to expel waste gases and regulate the room temperature; keep the room temperature at 32-34°C, keep the relative air humidity at 85%-90%, reduce the amount of water sprayed, and increase the frequency of spraying. After each flush of mushrooms is harvested, promptly clean the surface of the material. On the premise of keeping the mushroom house temperature basically stable, spray water to retain moisture, adjust the pH to slightly alkaline, and promote mycelial recovery. While replenishing water, some nutrient solution can also be applied, such as 0.1% urea and 5% bran water, to promote the differentiation and development of fruiting bodies. After 7 days, the second flush of mushrooms can be harvested. If the goal is to harvest two flushes of mushrooms, one production cycle takes about 20 days.

Straw mushrooms grow extremely fast and often open their caps overnight, so they should be harvested in time. When the straw mushroom changes from a pagoda shape, wider at the base and slightly pointed at the top, to an oval shape, when the mushroom texture changes from firm to soft and loose, when the color changes from dark to light, and when the membrane is unbroken and the cap and stipe have not yet extended out, it is the most suitable time to harvest. Generally, harvest once each in the morning, at noon and in the evening. Freshly harvested mushrooms should promptly have the soil on the surface of the mushroom base trimmed off with a knife, and they can then be sold or processed.