Detailed Explanation of the Open-Field Cultivation Technique for Shiitake Mushrooms Using Substitute Materials

Recently, Gutian County in Fujian Province hosted the National Edible Fungi Technology Market. More than 700 people from research, production and management units as well as specialized household growers from 20 provinces, municipalities and autonomous regions gathered in Gutian. After visiting the county's field-cultivated shiitake mushrooms, everyone praised them without exception.

Gutian County uses a new technique for open-field cultivation of shiitake mushrooms with substitute materials, and mushrooms emerge 70-80 days after inoculation. On average, every 100 kg of sawdust or cottonseed hulls can produce 8-12 kg of dried shiitake mushrooms, which is more than 10 times the per-unit yield of the old log cultivation method, and the production cycle has been shortened from the original more than two years to 10 months. The product's shape, color and taste show no obvious difference from log-grown shiitake mushrooms. Last autumn, Ruan Yi, a specialized household grower in Zouyang Village, Dajia Township, cultivated 8,600 bags of shiitake mushrooms on 1 mu of idle winter field. By May of this year, he had harvested a total of 660 kg of shiitake mushrooms. After deducting costs, his net income was 10,640 yuan, making him a "ten-thousand-yuan household" overnight.

The key measures of this new technique are as follows:

1. Raw material selection: Use sawdust from broadleaf tree species of Fagaceae, Betulaceae, Aceraceae and Hamamelidaceae. Among these, sawdust from Castanopsis, Schima, maple, Acer, oak, Elaeocarpus and Quercus dentata is the best. Sawdust from tree species containing resin acids, essential oils or alcohols, such as fir, pine and camphor, should not be used. In addition, cottonseed hulls, sugarcane bagasse, corncobs, peanut shells, sunflower seed shells and the like can also be used as substitutes.

2. Preparation of culture material: 50 kg sawdust, 11.5 kg wheat bran, 1.25 kg cornmeal, 0.5 kg sugar, 1.5 kg gypsum, 70-75 kg water. If cottonseed hulls are used as the raw material, the formula is: 50 kg cottonseed hulls, 10-12.5 kg wheat bran, 1.5 kg gypsum powder, 0.5 kg sugar, 70-75 kg water. Other substitute material formulas can also refer to the above proportions, except that the sugarcane bagasse formula should add 0.15 kg potassium dihydrogen phosphate solution, 0.15 kg urea and 0.1 kg magnesium sulfate. Stir the above raw and auxiliary materials evenly.

3. Bag filling and inoculation: Use special bags for shiitake cultivation sold on the market; either 160 x 0.08 mm polyethylene bags or 155 x 0.04 mm polypropylene bags are acceptable. The bag length is 50-60 cm, and each 50 kg of raw material fills 60-70 bags. The material should be packed with moderate tightness. After filling, tie the bag mouth tightly, punch 4 inoculation holes 1.5-2 cm deep and wide on the front of the bag, and seal them with adhesive tape. Then sterilize at 100°C under normal pressure for 10-12 hours. After cooling, move the bags into a sterile room, open the adhesive tape, inoculate with shiitake spawn, and stick the adhesive tape back in place.

4. Indoor spawn running: For the first 4 days, keep the indoor temperature at 25-28°C and do not exceed 30°C. A relative humidity of 70°C is suitable. After 4 days, adjust the temperature to 23-25°C. After 20 days, lift a corner of the adhesive tape over the inoculation openings to expose pores the size of soybeans, allowing air to enter the culture material. After another 30 days of cultivation, the mycelium in the bags is dense and white and grows robustly.

5. Outdoor primordia induction: When the dense white wavy mycelium accounts for 50% of the whole bag, move the bags to a field mushroom shed for bag-removal cultivation. Generally, the bags can be removed 6 days after inoculation. Cut open the bags with a blade and remove the plastic bags to form mycelial cylinders, then plant them on the mushroom bed under the shed frame and cover them with a large sheet of plastic film. Do not uncover the film for the first 3-5 days. After 6 days, turn the film over 2-3 times a day to make the mycelium lie flat. Under the stimulation of temperature differences, mushrooms generally emerge 15-20 days after bag removal.

6. Mushroom emergence management: After mushrooms emerge, control the mushroom bed temperature at 10-16°C and maintain the relative air humidity at about 90°C. After harvesting the first flush of mushrooms, strengthen ventilation and air exchange to promote mycelial recovery and growth, and artificially create a day-night temperature difference so that mushroom primordia reappear in large numbers. After harvesting 2-3 flushes, the mycelial cylinders become dry and should be soaked in water for 8-12 hours.

7. Harvesting and processing: When shiitake mushrooms grow to 70-80% maturity, that is, when the edges of the caps curl inward, they should be picked for market. When processing dried mushrooms, they should be baked over charcoal or coal fire. The initial temperature is 40-50°C; when moisture evaporates, raise it to 60°C and maintain for 1-2 hours, then lower it to 40°C until completely dried.