Cultivation of oyster mushrooms (Pleurotus pulmonarius) during the summer idle period can utilize shiitake mushroom sheds in high-altitude mountainous areas

Pleurotus pulmonarius is a medium-temperature variety, with a fruiting range of 15-28°C and an optimum of 18-22°C, and can fruit naturally in spring and autumn. Because Pleurotus pulmonarius has the characteristic of fruiting under variable temperature, under environmental conditions above the fruiting temperature range, proper low-temperature differential stimulation (temperature difference above 10°C) can promote fruiting body formation. In current production, during the summer high-temperature season when temperatures exceed 28°C, the method of placing physiologically mature spawn bags in a 2-4°C cold storage for cold stimulation for 10-12h, then moving them to the mushroom house for fruiting, is adopted for off-season cultivation. This off-season cultivation method is very suitable for enterprises and large growers to carry out large-scale, intensive production. However, because this off-season cultivation method requires, in addition to the mushroom house, the construction of a cold storage, and the spawn bags need to be moved back and forth between the mushroom house and the cold storage, it not only requires relatively large investment, but also consumes labor and effort, resulting in relatively high production costs.

If the cool summer climate and day-night temperature difference in high-altitude mountainous areas can be utilized to carry out off-season Pleurotus pulmonarius production under natural conditions, the investment and production costs of off-season Pleurotus pulmonarius production can be reduced. Therefore, researching and developing off-season cultivation technology for Pleurotus pulmonarius at high altitude has important practical significance. In the summer of 2004, we conducted an off-season cultivation experiment of Pleurotus pulmonarius in Hedi Village, Hedi Town, Qingyuan County at an altitude of 1040m, and achieved success. The first flush was harvested in early August, with a biological efficiency of 60%. The high-altitude off-season cultivation technology for Pleurotus pulmonarius is now preliminarily summarized as follows.

1 Selection of high-quality, high-yield strains. There are relatively large differences in mushroom shape and quality among different strains of Pleurotus pulmonarius. For example, some strains have short and thick stipes, some strains have relatively large caps and slender stipes, and some strains have relatively loose mushroom texture. During cultivation, strains should be selected according to market requirements to meet customer needs. The new strain "Nongxiu No. 1" bred by our institute has a cap size of 1-3cm, a stipe length of 3-5cm and a thickness of 1-1.5cm, firm fruiting bodies, light gray caps and white stipes, good commercial quality and high yield, and has been tested as suitable for cultivation in high-altitude areas.

2 Arrangement of cultivation season. The conventional cultivation season for Pleurotus pulmonarius is generally from September to May of the following year, with the fruiting period concentrated from mid-to-late October to late November and from late April to May. Based on the characteristics of Pleurotus pulmonarius fruiting at medium temperature and fruiting under variable temperature, combined with the climate characteristics of cool summers and large temperature differences at high altitude, experiments have shown that off-season cultivation at high altitude can be arranged from July to September, which can completely stagger the fruiting season in low-altitude areas, so as to achieve the purpose of filling the market gap and obtaining a good price. The production time for cultivation bags should be arranged in May.

3 Bagging and sterilization. ① Formula: cottonseed hull 33%, sawdust 55%, wheat bran 5%, corn flour 2%, brown sugar 1%, calcium carbonate 1%, gypsum powder 1%, lime 2%. When making bags during the high-temperature period, the amount of lime used in the ingredients should be increased to 3%, which can avoid acidification of the substrate that inhibits the growth of Pleurotus pulmonarius mycelium and can effectively prevent contamination by foreign bacteria. At the same time, the water content of the substrate should be controlled at about 60% to shorten the mycelial growth cycle and improve the quality of mycelial growth. ② Bagging and sterilization: select high-quality polyethylene or polypropylene plastic bags with specifications of 18cm x 36cm x 0.045cm, and plastic collars with an inner diameter of 3.5cm and a height of 3cm. The amount of substrate loaded can be slightly less than that for conventional seasonal cultivation on the plains, with about 500g of dry material per bag. When bagging, do it lightly, handle lightly, and place lightly, and use double collars for sealing, which provides good ventilation and is conducive to mycelial growth; during bagging and transportation, care should be taken to prevent the bags from being pierced by sand particles or sharp objects, so as to avoid contamination by foreign bacteria. After bagging is completed, they should be put into the sterilization stove promptly. When loading the stove, a certain gap should be left between the bags in the stove so that steam can evenly reach all bags and avoid sterilization dead corners. Use high-pressure sterilization, requiring maintenance at 1.5kg pressure for 3h; for atmospheric pressure sterilization, maintain for 14-16h after the temperature in the stove reaches 100°C. After sterilization, the bags should be promptly moved into a cooling room or inoculation room.

4 Inoculation and mycelial growth management. When the substrate temperature drops below 28°C, inoculate with spawn under aseptic operation in an inoculation box (room). After inoculation, place in a ventilated, cool room for mycelial growth. The temperature of the mycelial growth room should preferably be controlled at 23-25°C. If inoculation is carried out early (early May), the temperature in high-altitude areas is still low, so centralized stacking can be adopted, using self-generated heat to raise the temperature of the culture room, and heating measures can be taken when necessary to meet the temperature required for Pleurotus pulmonarius mycelial growth; in the later stage of mycelial growth culture (mid-to-late June to July), if the daytime temperature is too high (above 30°C), measures should be taken to close doors and windows during the day to prevent hot air from invading the culture room, and ventilate at night to lower the temperature, so as to regulate the culture room temperature and maximize meeting the needs of Pleurotus pulmonarius mycelial growth and post-ripening; check the temperature of the spawn bags promptly, and if the temperature is too high, promptly reduce the number and density of stacked layers to dissipate heat and prevent high-temperature burning of the mycelium. The light in the culture room should preferably be dim to prevent primordia from appearing too early on the upper part of the bags. After the mycelium has fully colonized the bags, when the temperature is about 25°C, continue culturing for 20d before carrying out fruiting management.

5 Mushroom shed preparation and fruiting management. Select a site with good ventilation as the fruiting site, and use idle-period shiitake (flower shiitake) sheds for summer cultivation. Before the spawn bags are moved into the shed for fruiting, appropriately increase the thickness of the shading material on the shed roof to prevent direct sunlight from entering the shed; if conditions permit, channel flowing mountain water into the shed; during the high-temperature period, spray water on the shed roof to cool it down and maximize the creation of a cool environment, keep the inside of the mushroom shed and the surrounding environment clean, and spread a layer of lime on the ground inside the shed. Move the spawn bags that are fully colonized with mycelium and have undergone post-ripening to the shiitake shed, cut off the bag openings along the substrate surface, and stack them in wall style on the low layers 1, 2, 3 of the flower shiitake cultivation racks, increase ventilation at night, and make full use of the day-night temperature difference at high altitude to induce budding and fruiting; at this time, measures such as spraying water and moisturizing the mushroom shed should be used to keep the substrate surface moist. After spraying water, ventilation should be strengthened, and note that water should not be sprayed on the substrate surface during high daytime temperatures. During the period of budding and fruiting body growth and development, methods such as keeping the ground moist and spraying water into the air should be adopted to maintain the humidity in the mushroom shed at 85%-90%, and avoid directly spraying water onto the fruiting bodies to prevent mushroom death. After one flush is finished, clean the substrate surface, stop watering and rest the mycelium for 5-7d, then follow the first-flush method to induce budding and fruiting through water spraying and temperature difference stimulation.

After fruiting, Pleurotus pulmonarius grows quickly. When it reaches the commercial standard required by the market, harvest it in batches in a timely manner. Because summer temperatures are high, after harvest it should be promptly put into cold storage for pre-cooling and stored and transported to market at low temperature, so as to avoid acidification and yellowing of the fruiting bodies, which would lead to a decline in mushroom quality. After finishing one flush, promptly clean the substrate surface and prepare for the next flush. Generally, 5-6 flushes can be harvested.