Key Technical Points for Temperature Regulation in Edible Mushroom Cultivation

During the growth process of edible mushrooms, they need to decompose, absorb and utilize nutrients. This is a complex biochemical process that requires the participation of multiple enzymes. As catalysts, enzymes are a special type of protein, and their activity is constrained by various environmental factors, especially temperature. Both excessively high and excessively low temperatures reduce enzyme activity. Therefore, in cultivation, properly regulating temperature is extremely important for every growth stage of edible mushrooms.

I. The "Three Cardinal Points" of Temperature Regulation at Different Growth Stages

In edible mushroom cultivation, temperature directly affects the progress of each growth stage, determines the length of the production cycle and the success of cultivation, and is also one of the determining factors for the quality and yield of edible mushroom products. Different species and different strains of edible mushrooms, as well as their different growth stages, all have different temperature requirements.

In cultivation, different temperature types are classified based on the optimal temperature for primordium differentiation. Taking shiitake mushroom (Lentinula edodes) as an example, high-temperature strains are 15-25°C, medium-temperature strains are 10-22°C, and low-temperature strains are 5-18°C.

Regardless of the type of edible mushroom or strain, at different growth stages, one should grasp its minimum growth temperature, optimal temperature and maximum temperature, which are the so-called "three cardinal points" of temperature regulation. The "three cardinal points" temperatures of common edible mushrooms are as follows: for shiitake mushroom (Lentinula edodes), the minimum, optimal and maximum temperatures for mycelial growth are 6°C, 24°C and 33°C respectively, and the minimum, optimal and maximum temperatures for fruiting body growth are 8°C, 18°C and 20°C respectively. For abalone mushroom (Pleurotus abalonus), the minimum, optimal and maximum temperatures for mycelial growth are 10°C, 25°C and 35°C respectively, and the minimum, optimal and maximum temperatures for fruiting body growth are 18°C, 25°C and 32°C respectively.

During the mycelial growth stage, most edible mushrooms are best kept at a controlled temperature of 25±1°C, while during the fruiting body growth stage, the requirements vary greatly among different mushroom types. In actual cultivation, the spawn-running stage is generally kept 2-3°C lower than the optimal temperature, and the temperature for primordium differentiation is generally 5-7°C lower than the optimal temperature for fruiting body growth.

It should also be mentioned that the above temperatures all refer to the "substrate temperature" inside the mushroom bag, which is different from the "room temperature" of the spawn-running room and the "air temperature" under natural climate conditions. As far as substrate temperature and room temperature are concerned, in the early stage of mycelial growth (within 15 days), the substrate temperature is lower than the room temperature, so the room temperature should be controlled above the optimal temperature. In the middle stage of mycelial growth (15-30 days), due to vigorous mycelial growth and heat release, the substrate temperature is 2-3°C higher than the room temperature, so the room temperature should be controlled 2-3°C below the optimal temperature.

II. The Issue of Spawn Age

Spawn age refers to the time required for a cultivation bag of edible mushrooms, after inoculation, to be cultured at the optimal temperature until physiological maturity and to enter the fruiting stage. This is also a very important issue in cultivation. Without understanding the spawn age required for culturing mushrooms, one cannot grasp the production season and may even cause failure. Different edible mushrooms have different spawn ages, and even the same species with different varieties or different cultivation methods will have different spawn ages. For example, for medium-high temperature type shiitake mushroom and medium-low temperature type shiitake mushroom, under the same 15×60 cm log-style bag cultivation, their spawn ages are 80 days and 120-160 days respectively. For abalone mushroom it is 60 days, and for poplar mushroom (Agrocybe aegerita) it is 50 days. However, these spawn-running days are only reference data. Whether physiological maturity has been reached should mainly be judged according to the unique characteristics of physiological maturity of each edible mushroom. For example, for wood-rotting fungi such as shiitake mushroom and nameko mushroom (Pholiota nameko), because mycelia often grow at unsuitable temperatures, their nutrient accumulation is insufficient, and large amounts of substances unfavorable to fruiting body formation accumulate during metabolism, resulting in delayed fruiting or severe log rot. From this it can also be seen that the influence of temperature on mycelial physiological maturity is a very long process, not limited to just a few days during the spawn-running period.

III. The Issue of Accumulated Temperature

The total sum of temperature necessary for a plant (including edible mushrooms) to complete one growth cycle is called accumulated temperature.

At present, there is not much research on accumulated temperature for edible mushrooms in China. Abroad, such as in Japan, more attention is paid to it. According to their research, generally for low-temperature varieties of shiitake mushroom cultivated on log segments, the effective accumulated temperature required is 4000-5000°C, and for high-temperature varieties it is 3000-4000°C. From a practical perspective, the accumulated temperature required for sawdust cultivation of shiitake mushroom in China is much less. According to calculations in Gutian County of our province, for sawdust bag cultivation of shiitake mushroom, the medium-low temperature type 087 strain inoculated on August 25, cultured at suitable temperature until fruiting on November 2, totaled 68 days. The average daily temperature during the spawn-running period was 21.3°C, and its effective accumulated temperature was 1108°C.

In actual cultivation, if attention is not paid to suitable temperature culture and the issue of accumulated temperature during the spawn-running period, the spawn age will be greatly extended, physiological maturity will not be reached for a long time, and fruiting will be affected. This phenomenon occurs in edible mushrooms such as tea tree mushroom (Agrocybe cylindracea), king oyster mushroom (Pleurotus eryngii), Hypsizygus marmoreus, Pleurotus ferulae, and enoki mushroom (Flammulina velutipes).

In production, for those using natural climate for cultivation, the effective way to regulate temperature is to grasp the local climate conditions and the characteristics of the mushroom strain, and formulate scientific seasons for spawn production, bag production, spawn running and fruiting. For those with regulation facilities, temperature control and other management measures can be set according to production requirements. However, temperature is only one of many ecological factors in the life of edible mushrooms. In practice, edible mushroom cultivation is affected by many factors. To obtain high quality and high yield, it is still necessary to grasp comprehensive ecological conditions and apply them flexibly.