Method for making shiitake mushroom (Lentinula edodes) spawn in plastic bags

The method for making spawn using 17 cm × 33 cm polypropylene plastic bags has already been described in the production of spawn for block cultivation. In recent years, substitute-material shiitake mushroom production has developed rapidly in northern China. Due to differences in climatic conditions and other factors, most northern regions adopt large-bag cultivation. Since large-bag cultivation also uses plastic bags as containers for spawn production, its operational precautions and technical key points are the same, but some specific operations differ.

Large-bag cultivation uses low-pressure high-density polyethylene plastic tube bags, 0.5-0.6 mm thick, 22-25 cm wide and 55-58 cm long, with each bag holding 1.5-2.0 kg of dry material. Substrate formula: sawdust 80%, wheat bran 20%, gypsum 1.5%, lime 0.2%-0.3%; material-to-water ratio 1:0.9, best judged by squeezing the material in the hand until water shows between the fingers but does not drip. Bag sterilization is a key technical step in large-bag cultivation. Sterilization operations should adhere to the principle of "strong attack at the start, maintenance at the end, and control in the middle," ensuring the temperature rises to 100°C within 6 hours. At the start, use a fierce hot fire; in the middle, frequently add hot water, prevent air leakage, and avoid temperature drops; keep a gentle fire at 100°C for 18-20 hours; finally, use a fierce fire for 2-4 hours, then let it sit for 1-2 hours. When the temperature drops to 70-80°C, slowly open the door and remove the bags. Sterilization time is positively correlated with sterilizer volume and substrate stick thickness. As the sterilizer capacity increases and the sticks become thicker, sterilization time should be increased, generally maintaining 100°C for about 24 hours, up to a maximum of 40 hours. Inoculation uses three-side 9-hole (3×3) inoculation. During inoculation, strictly maintain aseptic operation to prevent contaminating microorganisms from invading the inoculation holes. Stack in a "well" pattern for mycelial running, with stack spacing of 10 cm and height of 6-7 layers. After inoculation, turn the stack for the first time 10-15 days later, while checking mycelial growth and contamination. After that, turn the stack once every 10 days. During the first week of mycelial running, control the room temperature at 25-26°C; afterward control it at 20-24°C, and the bag temperature at 24-26°C. Strictly prevent the bag temperature from exceeding 28°C; control relative air humidity at 60%-65%. When there is a lot of rain, place quicklime indoors to absorb moisture and close doors and windows. When the inoculation holes reach 8-10 cm in diameter, increase ventilation and loosen the spawn sticks to help aeration and promote mycelial growth.