Detailed Explanation of Key Points of Bag-Grown Shiitake Mushroom Cultivation Technology

Shiitake mushroom (Lentinula edodes) is one of the earliest edible fungi to be artificially cultivated in China. The traditional cultivation method was mainly based on log cultivation. Log-cultivated shiitake mushrooms have a dense texture and excellent quality, but the production cycle is long, the yield is low, and the cost is high. Substitute substrate cultivation technology has the advantages of a wide range of raw material sources, a short production cycle, high yield, and large returns, and has become the main method of shiitake mushroom cultivation today. The production process of substitute substrate cultivation of shiitake mushrooms can be roughly divided into three aspects: bag making, bag removal and color change, and fruiting management.

1. Bag making. Shiitake mushroom is a saprophytic fungus. It does not contain chlorophyll itself and cannot carry out photosynthesis. It can only absorb carbohydrates and nitrogen-containing compounds as well as a small amount of minerals and auxins from the substrate provided to it for growth.

Commonly used formulas include:

1. Mixed wood sawdust 78%, wheat bran 20%, sugar 1%, gypsum 1%, water 120-125 jin, pH natural.

2. Mixed wood sawdust 78%, wheat bran 15%, wheat flour with bran 5%, gypsum 1%, superphosphate 1%, water 120-125 jin, pH natural.

3. Mixed wood sawdust 40%, cottonseed hull 40%, wheat bran 18%, sugar 1%, gypsum 1%, water 120-125 jin, pH natural.

4. Mixed wood sawdust 20%, bagasse 58%, wheat bran 20%, sugar 0.5%, gypsum 1.5%, water 120-125 jin, pH natural.

5. Cottonseed hull 90%, wheat bran 8%, sugar 1%, gypsum 1%, water 110-130 jin, pH natural. All the above raw materials must be fresh, free from mold, and free from insect damage. Among them, sawdust from pine, fir, and nanmu and camphor wood that contain more aromatic substances cannot be used for substitute substrate cultivation of shiitake mushrooms.

When using the above formulas, adding 0.1% carbendazim (50% content) has a certain effect on inhibiting contaminating fungi. That is, add 1 kg of carbendazim to 1000 kg of substrate.

Sterilize the culture substrate at 98-100°C for 10-12 hours. After the fungus bags cool, carry out inoculation, spawn running, and fungus bag cultivation. Strict aseptic operation must be carried out during inoculation. During fungus bag cultivation, the material temperature should be maintained at 18-23°C. During the mycelial cultivation process, the material temperature will gradually rise. When the material temperature reaches 25°C, turn the piles in time, and open doors and windows to dissipate heat. After 5-7 days of inoculation, it is necessary to check whether the mycelium has colonized the substrate and whether there is contamination by other fungi, etc. After that, turn the piles once every 5-7 days. If contaminating fungi are found, they should be eliminated immediately. After 50-60 days of fungus bag cultivation, the fungus logs mature. When the mycelium in the bag becomes wavy or forms a few primordia, brown water droplets appear around some inoculation blocks (holes), and scattered primordia appear on the surface of the fungus logs, bag removal and color change can be carried out.

2. Bag removal and color change. The quality of bag removal and color change of shiitake fungus logs directly affects the earliness, quality, and yield of fruiting. Bag removal must be chosen on a sunny or cloudy day, with no northwest wind, and a temperature of 15-25°C. The most suitable temperature is 20-22°C. Use a small knife to gently cut the film and carefully tear it off. Place the fungus logs on the ground at a spacing of 10 cm and at an 80-degree slant. The color change of the fungus logs mainly depends on artificially regulating and controlling the microclimate inside the covering film.

The specific method is: after the fungus logs are removed from the bags, if the temperature inside the film is between 20-22°C and the relative air humidity is 85%, do not lift or move the film for 3-5 days, so that the mycelium can adapt to the new environment and resume normal growth. However, when the temperature exceeds 25°C, the film should be opened the next day for ventilation and cooling. If the temperature is below 20°C, open the film for ventilation only after 7-8 days. In short, first the mycelium on the surface of the fungus logs must resume growth and grow a layer of thick white aerial mycelium before starting to lift and move the film. The purpose of lifting and moving the film is to increase oxygen, lower temperature, prevent excessive vegetative growth of mycelium, and prevent mold damage. Under normal circumstances, within 3-7 days after bag removal, ventilate and exchange air 1-2 times a day for 20-30 minutes each time. When pale yellow water droplets appear on the fungus logs, spray lightly with a sprayer once, then cover the film tightly so that the yellow water is evenly distributed on the surface of the fungus logs. The next day, use a sprayer to wash and spray the fungus logs, wash off the yellow water, and ventilate until the surface of the fungus logs is dry and not sticky to the touch but slightly tacky. Then cover the film again and do not lift or move it for 3-5 days. After that, lift and move the film at 9 a.m. and 3 p.m. every day for ventilation and air exchange, release moisture, increase scattered light, and widen the difference between wet and dry on the surface of the fungus logs. Repeat this for 2-3 days to enable the fungus logs to change color normally. From bag removal to completion of color change generally takes about 15 days.

3. Fruiting management. After 15-20 days from bag opening, the fungus logs have already changed color normally. The mycelium has stored extremely rich nutrients, and the mycelium vitality is very strong. At this time, a certain dry-wet difference, day-night temperature difference, and light stimulation must be provided. When the mycelium suddenly receives the effect of a harsh external environmental condition, the mycelium vitality will relatively weaken and begin to transform from the vegetative stage to the reproductive growth stage, intertwining and knotting with each other to form primordia, which then become mushroom buds. When the mushroom buds grow to the size of soybean grains, sufficient water should be supplied in time to facilitate the growth of the fruiting bodies.

The specific method is: in areas with small day-night temperature differences, generally the following must be adopted: cover the film on the mushroom bed during the day to reduce ventilation and air exchange and increase the temperature of the microclimate in the bed. At night, it is best to open the film at 4 a.m. so that the temperature of the mushroom bed drops suddenly, artificially creating a temperature difference. Doing this continuously 3-4 times can make the fungus logs produce primordia and develop from primordia into mushroom buds. When the temperature remains at 20-22°C, do not open the film for 3 consecutive days and nights. After 4 days of sealing, open the film when the nighttime temperature is relatively low and combine it with watering to lower the temperature. This can also promote fruiting. When continuous low temperature occurs, part of the shading material above the mushroom yard can be appropriately removed during the day, using sunlight to raise the mushroom bed temperature to above 15°C, which may also enable primordia to form mushroom buds and fruit smoothly. When buds appear, the humidity in the shed should be increased to about 85%. After the first batch of shiitake mushrooms is harvested, it is necessary to stop for 3-5 days, open the covering film, and increase the number of ventilation and air exchanges to facilitate the recovery and knotting of the mycelium. When the mycelium in the harvested area turns white, it indicates that growth has resumed. Then raise the temperature and create a day-night temperature difference to promote the formation of the second batch of mushroom buds. When the mushroom bodies grow to 2 cm, begin spraying water in the form of mist. When the temperature is above 20°C, spray water in the morning and evening.

After the second batch of mushrooms is harvested, manage them again according to the first batch. After several batches of mushroom growth, when the water content in the fungus logs drops to about 35% of the original weight, they are no longer easy to fruit. Spraying water can no longer meet the water requirements for fruiting. The method of soaking or injecting water must be adopted to make the fungus logs reach their original weight and restore their fruiting capacity. When soaking or injecting water, do not let the fungus logs absorb too much water, otherwise the fungus logs will rot and disintegrate and lose their fruiting capacity. After soaking, cover the film well, ventilate and exchange air 1-2 times a day, and widen the temperature difference stimulation to promote primordium formation. When the shiitake fruiting bodies grow to eight-tenths mature, the edge of the cap rolls inward slightly to form a "gong rim," and the mushroom turns from white to pale yellow, the quality is optimal. They should be harvested and processed in time.