Detailed Explanation of High-Altitude Off-Season Cultivation Techniques for King Oyster Mushroom

    King oyster mushroom (Pleurotus eryngii), also known as xuerong, has thick flesh, a delicious taste and a high oligosaccharide content. Taking advantage of the climate advantage of early autumn coolness in the high mountain areas, our county demonstrated and promoted the cultivation of this variety in three townships, Chengyuan Township, Zhenqian Town and Yangyuan Township (average altitude above 800 m), with more than 1 million bags. The fruiting period was about 1 month earlier than in the plain areas (altitude around 200 m), and product sales were very promising. The average selling price of fresh mushrooms was 10-12 yuan/kg, with obvious economic and social benefits. A summary is given below: 

    1. Morphological characteristics 

    1.1 The fruiting body is solitary or clustered. The cap is 4-6 cm wide, initially round, later becoming flat, slightly depressed in the center, and funnel-shaped at the late stage. At maturity it is grayish brown, with an incurved margin. The flesh is white and has an almond flavor. 

    1.2 The gills extend downward and are milky white. The stipe is white, 5-15 cm long, lateral, sometimes central, stout, tapering at the apex, solid, finely fleshy, fibrous, and without an annulus. 

    2. Physiological characteristics 

    2.1 Temperature Temperature is an important factor determining the growth and development of king oyster mushroom and is also the key to stable production. The mycelial growth temperature is 22-25°C; the primordium formation temperature is 10-18°C, with the optimum at 12-15°C; fruiting body development requires 8-20°C, with the optimum at 12-16°C. Below 8°C, the fruiting body is difficult to differentiate; above 29°C, the fruiting body easily dies. 

    2.2 Humidity Since water should not be sprayed on the mushrooms during cultivation, moisture is mainly supplied by the substrate, so the substrate moisture content is 65%-70%, which is more suitable for fruiting body initiation and growth. The relative humidity required during the fruiting body formation stage is 90%-95%, and during the growth stage 85%-90% is appropriate. 

    2.3 Light The mycelial growth stage does not require light; under dark conditions, mycelial growth is faster. Fruiting body formation and development require scattered light. If the light is too strong, the mycelium turns black; if the light is too dim, the cap turns white and the stipe becomes longer. 

    2.4 Air During the mycelial growth stage, the air requirement is not strict, and carbon dioxide stimulates and promotes mycelial growth. However, primordium formation and fruiting body growth require sufficient oxygen. 

    2.5 pH During the growth stage, the pH is 4-8, with the optimum at pH 6.5-7.5. At pH below 4 or above 8, fruiting is difficult. 

    3. Cultivation techniques 

    3.1 Cultivation substrate formula Sawdust 30%, cottonseed hull 45%, wheat bran 22%, calcium carbonate 1%, gypsum powder 1%, lime 1%.
 
    3.2 Seasonal arrangement For cultivation in mountain areas above 800 m in altitude, bag making and inoculation should be arranged in early to mid-August, and harvesting from mid-October to April of the following year. 

    3.3 Strain selection There are many strains of king oyster mushroom, mainly the following three types. 

    ① Thick-long type: the fruiting body is thick and long, large, with concentrated fruiting and high yield, but the mushroom body is relatively loose; ② Slender type: the fruiting body is slender, the flesh is firm, the quality is good, and the yield is relatively low; ③ Bowling-pin type: the fruiting body resembles a vase or bowling pin, with relatively high yield and a long fruiting period. Strains should be selected according to market requirements to meet the needs of buyers. 

    3.4 Making cultivation bags Use 17 cm x 33 cm polypropylene gusseted bags, each filled with 0.8-0.85 kg of wet substrate, with a filling height of 13-15 cm. The substrate should be pressed firmly and packed tightly, sealed with a sponge ring, and sterilized at atmospheric pressure, kept at 100°C for 12 hours. After sterilization, cool until the substrate temperature drops below 28°C, then begin inoculation. After inoculation, choose a ventilated, cool environment and arrange 80-120 bags per square meter. During the mycelial running period, control the temperature at 20-25°C. 

    3.5 Fruiting management The fruiting site should be spacious and well ventilated. After the mycelium has fully colonized the bags, when the air temperature drops below 16°C, open the bags and fold the bag mouths down to 5-6 cm above the substrate surface. Cover with plastic film to raise the mushroom house humidity to 90%-95%, and at the same time increase scattered light stimulation. After about 10 days, fruiting bodies appear in large numbers. At this time, remove the plastic film and thin the buds, keeping only 4-5 mushrooms per bag, and keep the mushroom house dark so that the fruiting bodies are white and long.  

    3.6 Timely harvesting Harvest when the caps have expanded and the spores have not yet been discharged. Generally, 2-3 flushes of mushrooms are harvested.