Pollution-free Cultivation Techniques for Pleurotus pulmonarius at High Altitudes in Summer

Pleurotus pulmonarius, also known as yellow-white oyster mushroom, lung-shaped oyster mushroom, pocket mushroom, Ji pinggu, small pinggu, etc., taxonomically belongs to the phylum Fungi, subphylum Basidiomycotina, class Hymenomycetes, order Agaricales, family Pleurotaceae, genus Pleurotus, and is named for its elegant appearance and delicious taste. Pleurotus pulmonarius is rich in protein, sugars, vitamins, and trace elements such as iron and calcium; in particular, its protein content is higher than that of button mushrooms, shiitake mushrooms, straw mushrooms, and other edible fungi, hence it is also called the "finest of mushrooms." Pleurotus pulmonarius can be stir-fried, cooked in soup, or used for hot pot, and is deeply favored by consumers; its market sales and cultivation volume have increased year by year, making it an edible fungus with great development prospects. To make full use of the unique climatic conditions and ecological resources of the high-altitude platform in eastern Qingyuan County, Zhejiang Province, we carried out pollution-free summer cultivation of Pleurotus pulmonarius in Hedi Town, Qingyuan County. Through three consecutive years of introduction and expansion, a production scale of 200,000 bags has now been formed, the survival rate of fungal bags has reached over 90%, and the yield per unit can reach over 0.25 kg; some farmers have already achieved certain economic benefits. This technique is summarized below for reference by fellow practitioners.

1 Excellent summer climate resources of Hedi Town, Qingyuan County

Hedi Town has high terrain in the middle and low terrain in the north and south, with an average altitude of about 1000 m. It is a medium mountain platform with a relatively high altitude and the largest area in East China. The climate in the area belongs to the subtropical monsoon type, warm and humid, with an annual average temperature of 13.6°C and an average relative humidity of 84%. In particular, the average temperature in summer (June to September) is below 25°C, giving a fairly obvious advantage for off-season cultivation of Pleurotus pulmonarius. Hedi Town has overlapping mountain ranges, a forest coverage rate as high as 72.6%, good air quality, clean water sources, and no industrial pollution or other pollution, which also provides excellent ecological and environmental conditions for pollution-free cultivation of Pleurotus pulmonarius.

2 Biological characteristics of Pleurotus pulmonarius

2.1 Nutrition

Pleurotus pulmonarius is a wood-rotting fungus and has a strong ability to decompose lignin, cellulose, and hemicellulose. The raw materials commonly used in production mainly include cottonseed hulls, broadleaf tree sawdust, corn cobs, sugarcane bagasse, and other crop straws. Supplementary materials mainly include wheat bran, rice bran, gypsum, lime, etc. When mixing ingredients, the C/N ratio of the culture material must be well controlled to create excellent nutritional conditions for improving mushroom quality.

2.2 Temperature

Pleurotus pulmonarius is a mesophilic fungus. The temperature for mycelial growth is 3-28°C, with the optimum mycelial growth temperature at 25°C; the growth temperature for fruiting bodies is 5-27°C, with the optimum at 15-20°C; the fruiting temperature is 15-25°C, with the optimum at 18-22°C, and fruiting requires stimulation by a temperature difference of 8-10°C.

2.3 Humidity

The water content of the culture material depends on the specific raw materials. The commonly used mixture of cottonseed hulls and sawdust in production should be kept at 60%-65%. During the mycelial growth stage, there is no great requirement for air relative humidity; during the fruiting stage, the air relative humidity should be raised to 90%-95%; during the fruiting body growth stage, the air relative humidity is about 90%; excessively high air relative humidity will affect the normal differentiation of the cap and stipe.

2.4 Oxygen

Pleurotus pulmonarius is an aerobic fungus, and sufficient oxygen is required during both the mycelial growth and fruiting body growth stages. Insufficient oxygen supply will cause poor mycelial growth and the occurrence of deformed mushrooms. However, at any growth stage, Pleurotus pulmonarius has a certain tolerance to carbon dioxide, and during fruiting the carbon dioxide concentration can also be controlled to improve mushroom quality.

2.5 pH value

The most suitable pH value for Pleurotus pulmonarius is 7.2-7.5. In production, 2%-3% quicklime is commonly used to adjust the pH value of the culture material, which can not only promote mycelial growth but also inhibit mold infection during high summer temperatures.

2.6 Light

Pleurotus pulmonarius does not require light during mycelial growth; mycelia can grow normally under completely dark conditions. However, during fruiting, appropriate light stimulation must be provided for normal differentiation and formation of mushroom buds. Light can also affect mushroom quality: the higher the light intensity, the darker the mushroom color; the lower the light intensity, the lighter the mushroom color; at the same time, the lower the light intensity and the higher the air humidity, the longer the mushroom stipe.

3 Pollution-free summer cultivation techniques at high altitudes

3.1 Selection of cultivation season at high altitudes

The selection of the summer cultivation season for Pleurotus pulmonarius in Hedi Town, Qingyuan County, Zhejiang Province, needs overall consideration based on the climatic conditions of Hedi Town and the requirement to fill market gaps. In combination with the climatic characteristics of Hedi Town and the requirements of pollution-free cultivation, the seasonal arrangement should be "earlier rather than later." For large-scale planting, bag making can begin in early April, mycelial growth can end by the end of May, and fruiting can begin in early June. This can not only ensure the survival rate of fungal bags and improve the ability of mycelia to resist pests and diseases, but also allow the first flush of mushrooms to fruit during a more suitable temperature period, improving yield and quality. Pleurotus pulmonarius marketed during this period sells at a high price, greatly improving the economic benefits of Pleurotus pulmonarius production.

3.2 Site selection

Choosing a good cultivation site is a prerequisite for pollution-free production of Pleurotus pulmonarius. The cultivation site should be selected in villages with convenient transportation, sufficient water sources, good water quality, timely fuel supply, and guaranteed electricity. The surroundings of the cultivation site should have good air circulation and good environmental quality (including air quality and water source quality, etc.). It must not be built near breweries, slaughterhouses, hospitals, or garbage dumps to reduce the impact of pollution sources. According to on-site investigation, most places in Hedi Town can meet the above requirements.

3.3 Mushroom shed construction