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Hericium erinaceus growth: required temperature and humidity

1. Temperature

Hericium erinaceus is a mesophilic edible fungus. The temperature required for the growth of its mycelium is different from that for the formation of its fruiting body. The mycelium growth stage requires a higher temperature, while the fruiting body formation stage requires a lower temperature. The mycelium of Hericium erinaceus can grow at 6~33°C, and the optimum growth temperature is about 25°C. When the temperature is high, the mycelium is thin and sparse, grows slowly at 33°C, and stops growing completely when it exceeds 35°C. When the temperature is lower, the mycelium is thick, dense, white, grows vigorously, and has strong vitality. When the temperature is lower than 6°C, the mycelium almost stops growing.

Fruiting bodies can be differentiated and formed at 6~24°C, but 16~20°C is the most suitable. For strains that have not been bred in a directional manner, fruiting bodies cannot be formed when the temperature exceeds 25°C. When the temperature is too low, the differentiation and growth of fruiting bodies are slow, and when it is lower than 6°C, the fruiting bodies stop growing completely. The temperature also affects the morphology of fruiting bodies. When the temperature is high, the fruiting body has long spines, small balls, and is soft, and often forms branches; when the temperature is low, the spines are short, the balls are large and compact; when the temperature is below 12°C, the fruiting body is often orange-red.

The adaptability of Hericium erinaceus to temperature is easy to change. When it grows on sugarcane bagasse and wheat bran culture medium, the mycelium is easy to differentiate into fruiting bodies because the culture medium material is loose and has good ventilation. If it is separated and cultured on this culture medium many times, the formation of fruiting bodies will become faster and faster, and the temperature adaptation range will become wider and wider. The parent that can only form fruiting bodies at the highest temperature of 22°C can form fruiting bodies in the range of 6~28°C.

2. Humidity

Water is an important component of Hericium erinaceus mycelium and fruiting body cells. Generally, the water content of fresh Hericium erinaceus is about 85%. Water is an indispensable basic substance for the metabolism and absorption of nutrients of Hericium erinaceus. All physiological activities of Hericium erinaceus, including the absorption and transportation of nutrients, the secretion of enzymes, and the decomposition and utilization of complex substances such as cellulose and lignin, must be carried out under certain moisture conditions; however, the moisture content should not be too much, as too much moisture will affect the ventilation in the culture medium. It will affect the respiration of mycelium and cause excessive dilution of the cell protoplasm, thereby reducing stress resistance and accelerating its aging. The so-called humidity in production refers to the water content of the culture medium and the relative humidity of the air in the cultivation environment.

(1) Water content of culture medium

The water contained in the culture medium is the most important source of water required by Hericium erinaceus. Only when the culture medium contains sufficient water can the fruiting body form normally. The suitable water content for the growth of Hericium erinaceus is closely related to the physical properties of the culture medium. If the texture of the culture medium is solid, the water content is low; otherwise, the water content is high. Culture medium with a dense texture such as sawdust requires a lower water content, preferably about 55%; culture medium with a loose texture such as cottonseed hulls and sugarcane bagasse requires a higher water content, preferably about 65%. 

(2) Relative humidity of the air

During the growth and development of Hericium erinaceus, the growth environment requires a certain relative humidity of the air. Generally, during the mycelium growth stage, the relative humidity of the air is required to be lower, preferably around 70%. If the humidity is too high, the contamination rate of the mushroom bag will increase exponentially; if the humidity is too low, the water in the culture medium will evaporate too quickly, affecting the mycelium growth.