Detailed Explanation of the Key Technical Points for Color-Turning Management of Shiitake Mushroom Logs

The color-turning management of mushroom logs can be divided into two methods: color turning after bag removal and color turning within the bag. Current production is mostly aimed at obtaining flower shiitake or high-quality thick shiitake, so the within-bag color-turning method is mostly adopted. Its basic management is as follows:

1. Perforation for oxygen enrichment: after the mycelium has fully colonized, the substrate is filled with mycelium, and its metabolic rate increases greatly. Perforation serves the purpose of increasing internal oxygen, expelling waste gas, boosting metabolism and dissipating part of the moisture, and is the first step of color-turning management.

2. Promoting separation of the film from the walls: through perforation, moving, and so on, prompt the plastic film to separate from the substrate. For early-maturing strains with a short colonization time, since natural separation from the walls is difficult, the plastic film can be lifted up along with the perforation, so as to facilitate the growth of aerial mycelium at that spot.

3. Stacking for ventilation: according to the temperature, use triangular or tic-tac-toe stacking, stacking the mushroom logs 4-8 layers high, which both makes full use of space and prevents the logs from being too crowded; moreover, the middle of the stacked pile has a "natural draft", which is favorable for ventilation between the bags and inside the film.

4. Regulating temperature: according to the season, appropriately regulate the temperature inside the pile by artificial means, keeping it at 15-25°C; in cold seasons the lowest temperature can also be regulated to around 10°C. When the temperature inside the pile reaches 25°C, the covering should be removed and the pile turned to dissipate heat. The principle is "rather extend the color-turning time at low temperature than allow high temperature to burn the mycelium".

5. Ventilation to suppress mycelium: under relatively suitable conditions, a fine, dense layer of aerial mycelium will quickly grow on the surface of the substrate and begin to secrete pigments, with light soy-sauce-colored water droplets appearing, which is an important signal of color turning. At this point, two measures can be taken. One is to spray directly with groundwater, which both cools the mushroom logs and washes away part of the pigment water droplets; at the same time, ventilation should be strengthened. Generally, it is enough that the substrate surface is not sticky to the touch 2 hours after spraying. The other is to turn the pile while strengthening ventilation.

6. Increasing the temperature difference: practice has proved that, under certain conditions, increasing the day-night temperature difference on the basis of cooling as much as possible is one of the main measures to promote color turning.

7. Alternating dry and wet: this measure can be achieved by means such as spraying cold water and strengthening ventilation. Spraying cold water, on the one hand, gives the mushroom logs a relatively large temperature-difference stimulus, prompting them to quickly form a mycelial film; on the other hand, it can raise the humidity, and by strengthening ventilation and other measures, the purpose of alternating dry and wet can be achieved.

8. Light stimulation: appropriate light stimulation is an important factor in promoting the color turning of mushroom logs. Under normal circumstances, the light intensity can be regulated to around 1000 lux, that is, relatively bright light; and by turning the pile or changing the light source, the mushroom logs receive uniform light, achieving the purpose of consistent, neat and uniform color turning.