The Latest Cultivation Techniques and Methods Tutorial for Shiitake Mushrooms
Shiitake mushroom, also known as xiangxun, xiangxin, xianggu, and zhuirong, belongs to the class Basidiomycetes, order Agaricales, family Pleurotaceae, genus Lentinula. The artificial cultivation of shiitake mushrooms in our country has a history of more than 800 years. For a long time, shiitake mushrooms were cultivated using the “cut-log method”, which is a natural inoculation log cultivation method. It was not until the mid-1960s that pure spawn began to be cultivated, and the method was changed to the artificially inoculated log cultivation method. In the mid-1970s, the substitute material block pressing cultivation method appeared, which later developed into the plastic bag cultivation method, and production increased significantly. Our country is currently the world's largest producer of shiitake mushrooms.
Shiitake mushroom is a famous edible and medicinal fungus, with a rich aroma and abundant nutrition. It contains 18 kinds of amino acids, 7 of which are essential to the human body. The ergosterol it contains can be converted into vitamin D, which has the effect of enhancing the human body's resistance to disease and preventing colds; lentinan has antitumor effects; adenine and choline can prevent cirrhosis and arteriosclerosis; tyrosinase has the effect of lowering blood pressure; double-stranded ribonucleic acid can induce the production of interferon and has antiviral effects. In folk practice, shiitake mushroom is used to detoxify, benefit stomach qi, and treat wind and break blood. Shiitake mushroom is one of our country's traditional special export products, and its first-grade product is flower shiitake.
Biological Characteristics
1. Morphological Characteristics
Shiitake mushroom mycelium is white, fluffy, with septa and branches, mostly clamp connections, twisting into a network after maturity, and forming a brown mycelial film after aging. The fruiting body is medium-sized to slightly large. The cap diameter is 5-12 cm, flatly hemispherical, with an incurved margin, gradually flattening after maturity, dark brown to dark cinnamon, with dark scales. The flesh is thick and white. The gills are white, dense, adnexed, and of unequal length. The stipe is central to off-center, white, solid inside, often curved, 3-8 cm long and 0.5-1.5 cm thick; a narrow annulus is borne on the middle part, easily broken and disappearing; below the ring there are fibrous white scales. Spores are elliptical, colorless, and smooth.
2. Living Conditions
① Nutrition: Shiitake mushroom is a wood-inhabiting fungus. It uses cellulose, hemicellulose, lignin, pectin, starch, and so on as carbon sources for growth and development, but these must be decomposed by corresponding enzymes into monosaccharides before they can be absorbed and utilized. Shiitake mushroom uses various organic and inorganic nitrogen as nitrogen sources. Small-molecule amino acids, urea, ammonium, and so on can be directly absorbed, while macromolecular proteins and peptones must be degraded before absorption. The growth of shiitake mushroom mycelium also requires various mineral elements, among which phosphorus, potassium, and magnesium are the most important. Shiitake mushroom also needs growth factors, including various vitamins, nucleic acids, and hormones. Most of these can be self-supplied, and only vitamin B 1 needs to be supplemented.
② Temperature: The optimum temperature for shiitake mushroom mycelium growth is 23-25°C. Below 10°C or above 30°C hinders its growth. The suitable temperature for fruiting body formation is 10-20°C, and a day-night temperature difference greater than 10°C is required. The shiitake mushroom varieties currently used in production include three temperature types: high-temperature type, medium-temperature type, and low-temperature type. Their suitable fruiting temperatures are 15-25°C for the high-temperature type, 7-20°C for the medium-temperature type, and 5-15°C for the low-temperature type.
③ Moisture: The moisture required by shiitake mushrooms includes two aspects: first, the water content within the culture medium, and second, the air humidity. The suitable amounts differ depending on whether substitute material cultivation or log cultivation is used.
[Substitute Material Cultivation] During the mycelium growth stage, the water content of the culture material is 55%-60%, and the relative air humidity is 60%-70%; during the fruiting stage, the water content of the culture material is 40%-68%, and the relative air humidity is 85%-90%.
[Log Cultivation] During the mycelium growth stage, the water content of the culture material is 45%-50%, and the relative air humidity is 60%-70%; during the fruiting stage, the water content of the culture material is 50%-60%, and the relative air humidity is 80%-90%.
④ Air: Shiitake mushroom is an aerobic fungus. In the growing environment of shiitake mushrooms, due to poor ventilation, excessive accumulation of carbon dioxide, and insufficient oxygen, mycelium growth and fruiting body development will be significantly inhibited, which accelerates the aging of the mycelium. The fruiting bodies are prone to deformities, and this also favors the breeding of contaminating fungi. Fresh air is a necessary condition for ensuring the normal growth and development of shiitake mushrooms.
⑤ Light: The growth of shiitake mushroom mycelium does not need light. Under completely dark conditions, the mycelium grows well, and strong light can inhibit mycelium growth. During the fruiting body growth stage, scattered light is needed. If the light is too weak, there will be few mushrooms, the caps will be small, the stipes will be slender, and the quality will be poor, but direct light is also harmful to shiitake mushroom fruiting bodies.
⑥ pH: The growth and development of shiitake mushroom mycelium require a slightly acidic environment. The pH value of the culture material can support growth from 3-7, with 5 being the most suitable. Above 7.5, growth is extremely slow or stops. The optimum pH value for the occurrence and development of fruiting bodies is 3.5-4.5. In production, the pH value of the cultivation material is often adjusted to about 6.5. High-temperature sterilization will cause the pH value of the material to decrease by 0.3-0.5, and the organic acids produced during mycelium growth will also lower the pH of the cultivation material.