Detailed Explanation of Key Points for Artificial Cultivation Techniques of Reishi Mushroom
Reishi mushroom has long been known as the "auspicious herb," and in myths and legends it is even hailed as a miracle cure capable of "bringing the dead back to life." Modern medicine has also proven that it has multiple pharmacological functions and high medicinal value.
1. Biological characteristics of reishi mushroom
Reishi mushroom is a wood-rotting macrofungus belonging to the order Polyporales, family Polyporaceae, genus Ganoderma. There are 50 species in the genus Ganoderma, and 41 species are distributed in China. The more common reishi mushrooms include Ganoderma sinense, Ganoderma tsugae, Ganoderma atrum, and Ganoderma violaceum. The mycelium of reishi mushroom is white and fluffy, and under a microscope a layer of white crystalline secretion can be seen on its surface, the composition of which is calcium oxalate. This is what distinguishes it from other edible fungi. The fruiting body of reishi mushroom is umbrella-shaped, woody or corky, and the cap surface has a hard crust with concentric or radial ridges, appearing purplish-red or brownish-red and glossy; beneath the cap are tubes perpendicular to the ground; the stipe is cylindrical and irregular, often curved, lateral, and the same color as the cap, and the cap often develops on one side of the stipe.
2. Conditions for the growth and development of reishi mushroom
(1) Temperature. The mycelium of reishi mushroom can grow at temperatures from 6 to 35°C, but grows relatively quickly within the range of 28 to 30°C. Below 25°C, growth gradually slows as the temperature decreases; from 30 to 35°C, growth gradually slows as the temperature rises; above 35°C, it quickly dies. The fruiting body may develop between 23 and 30°C, with around 25°C being most suitable for development.
(2) Humidity. In the artificial cultivation of reishi mushroom, humidity has two meanings: first, the water content of the substrate should reach about 60%; second, during the period when the fruiting body appears, the relative air humidity should preferably be between 85% and 95%. Humidity that is too high or too low will both have adverse effects on the development of the fruiting body.
(3) pH. Reishi mushroom prefers slightly acidic conditions, and grows better when the soil pH is around 5 to 6.
(4) Light. The mycelium of reishi mushroom grows faster under completely dark conditions than under illuminated conditions, and strong light has a clear inhibitory effect on mycelial growth. Different light qualities also have different effects on the mycelium: red light has a small inhibitory effect, while yellow light has a large inhibitory effect.
The development of the fruiting body of reishi mushroom is very sensitive to light. Although fruiting bodies can be produced from no light to strong light, the morphology of the fruiting body varies greatly.
(5) Air. Reishi mushroom is an aerobic fungus. When the carbon dioxide concentration in the air reaches 0.1% (normal content is 0.03%), it clearly promotes stipe growth but clearly inhibits cap growth, and may even prevent cap formation.
(6) Nutrition. Reishi mushroom is a wood-rotting fungus, and the nutrients required throughout its growth process are basically the same as those of wood-rotting fungi such as shiitake and oyster mushroom, and the nutrient sources are also largely the same. Carbon nutrition is mainly provided by sawdust, cottonseed hulls, and various straw materials, while nitrogen and auxin-like nutrients are provided by wheat bran, rice bran, soybean cake, cornmeal, and the like. Minerals mainly include calcium, magnesium, sulfur, phosphorus, and so on, and an appropriate amount of trace elements is also needed.
3. Artificial cultivation of reishi mushroom
(1) Culture medium formula. Commonly used culture medium formulas for artificial cultivation: ① 73% sawdust, 25% wheat bran, 1% sugar, 1% gypsum, and an appropriate amount of water (about 60% water content), such that when the material is tightly squeezed in the hand, water appears between the fingers. ② 70% fresh distillers' grains, 10% miscellaneous sawdust, 10% cornmeal, 8% rice bran, 1% lime, 1% superphosphate, 1% sugar, and 0.2% dipotassium hydrogen phosphate. If tofu water, soy milk, soy sauce, etc. can be added to the culture medium, or tofu residue waste or hickory shell can be used as the culture medium, the effect will be even better.
(2) Material selection and culture bottle preparation. Whether sawdust or bran, both are required to be fresh and dried in the sun for later use. Never use caked or moldy sawdust or bran. Mushroom bottles are generally used as cultivation bottles, but the cost is relatively high, so waste beer bottles with the neck removed can be used instead. An iron ring with an inner diameter of 3 cm can be fitted with a handle, heated red-hot on burning charcoal, then immediately fitted onto the bottle neck while continuously rotating the bottle body so that it is heated evenly, and afterward immersed in cold water prepared in advance to cut it off. At the same time, another person should use an iron tool to smooth the cut bottle mouth to prevent hand injuries. A larger bottle mouth makes bottling easier and is more conducive to improving aeration, which benefits the growth and development of the mycelium.
(3) Filling. When filling the culture material into bottles, it is better to make it tight rather than loose, and it should be evenly adjusted from top to bottom. If it is too loose, the fruiting body during growth will absorb nutrients from the culture medium, which often causes the phenomenon of the substrate pulling away from the bottle, seriously affecting further development of the fruiting body and being unfavorable for high yield. When filling, the material should be pressed tightly up to the shoulder of the bottle; neither too full nor too shallow is good. Then wash off or brush off the culture material on the outside of the bottle with a bottle brush, and plug the cotton plug properly.
(4) Disinfection. In rural areas, atmospheric-pressure disinfection or steam disinfection is mostly used, generally continuing for two hours under 100°C steam and then left overnight, so as to use the residual heat to dry the cotton plug.
(5) Inoculation. Inoculation should be carried out under sterile conditions. Because the temperature is already high during the production period and contaminating microorganisms are highly active, it is advisable to carry it out in the inoculation box in the latter half of the night or early morning when the temperature is relatively low. The inoculated stock culture should be kept as a whole piece (about the size of a broad bean) to avoid or reduce branching of the fruiting body.
(6) Management. In bottle cultivation of reishi mushroom, in addition to doing a good job in mycelial growth and development (mycelial incubation should be dark), when the fruiting body primordia grow out of the bottle mouth and gradually form fruiting bodies, efforts should be made to control the temperature at 28°C and keep the air fresh to avoid deformed growth. The development of the fruiting body of reishi mushroom does not require direct light but requires scattered light, and the fruiting body has obvious phototropism. During the formation of the fruiting body, its growth point always faces the light source, so the culture bottles should be placed upright, generally about 40 bottles per sq m.
(7) Bagging. Generally after 50 to 60 days of cultivation, the growth point at the edge of the fruiting body gradually disappears, and when its spores begin to be ejected, bagging should be carried out promptly. Bagging must be timely: if too late, the spores will be ejected, affecting yield; if too early, it is easy for the bag to stick. The bagging should be done carefully according to the direction of reishi mushroom growth, and the bag must never stick, otherwise reishi mushroom will grow outside the bag and affect yield improvement. At the same time, humidity management should be strengthened. Under conditions suitable for the growth and development of reishi mushroom, harvesting can generally be done after one month.