Key Techniques for Artificial Cultivation of the Medicinal Herb Lingzhi (Reishi Mushroom)

Lingzhi: also known as Jun Lingzhi or Mu Lingzhi, is a lower plant belonging to the family Polyporaceae. Its fruiting bodies and spores are used medicinally, with effects including nourishing, brain-boosting, strengthening, anti-inflammatory, diuretic, and stomach-tonifying properties.

I. Growth Habits

Lingzhi is a high-temperature saprophytic fungus. The fruiting body cannot differentiate or develop below 18°C, differentiates and develops relatively quickly between 24-28°C, and the mycelium grows within a temperature range of 3-40°C, growing most rapidly at 24-30°C. Spore germination and mycelial growth do not require light, while fruiting body differentiation and development require diffused light, with phototropism. It is aerobic, and poor ventilation affects growth and development, though it does promote the growth of the stipe. It also has relatively high requirements for air humidity, with 85-90% being suitable.

II. Cultivation Techniques

1. Bottle Cultivation

(1) Preparation of culture medium. The culture medium consists of sawdust and wheat bran in a ratio of 3:1. Broadleaf tree sawdust is usually used. Add an appropriate amount of water and mix thoroughly; the moisture level is right when water appears between the fingers but does not drip when squeezed tightly in the hand. Too much or too little water is detrimental to mycelial development and fruiting body formation.

(2) Filling bottles. The prepared culture medium is immediately packed into wide-mouth bottles and compacted. The appropriate filling amount is about 3-5 cm from the bottle mouth. Then, use a wooden stick or glass rod about 1 cm in diameter to poke a small hole from top to bottom in the center of the bottle to facilitate mycelial reproduction and spreading. The bottle mouth is plugged with two layers of gauze about 12 cm square sandwiching a cotton plug about 1 cm thick, wrapped with moisture-proof paper, and sterilized at 15 pounds of pressure for 1 hour.

(3) Inoculation. Under sterile conditions, take a slant culture that has been cultured at 24-26°C for about 5 days, use an inoculation needle to pick out a piece of mycelium (about 1.3 cm in diameter), open the cotton plug of the wide-mouth bottle, place the mycelium at the small hole in the center of the sawdust culture medium, then flatten the cotton plug back and wrap it for cultivation.

In order to expand the inoculation amount, it is best to use "seed" culture. The method is: mix wheat bran and water in a weight ratio of 1:2, load into petri dishes after mixing, press slightly, and every 10 grams of wheat bran can fill 4 glass dishes with an inner diameter of 8 cm. Place the dishes into cloth bags, sterilize under high pressure, then inoculate, and culture at 26-28°C for 5-7 days before use for bottle cultivation inoculation.

(4) Cultivation. ① Mycelial growth. Suitable temperature is conducive to rapid mycelial growth. A pH value of 5-6 is better for the culture medium, and the mycelial growth stage does not require light. Because the bottle mouth is plugged with a cotton plug, humidity and ventilation do not need additional control at this time. ② Fruiting body formation and differentiation. When the mycelium in the bottle has grown to a certain extent, fruiting body primordia (white bumps or protrusions about 1 cm in size) appear on the upper part, and at this point the cotton plug can be removed to allow growth out of the bottle mouth. The protrusions extend upward to form the stipe, and the cap then grows on the stipe. Spores can be released from the cap. Under suitable conditions, it takes about 40-60 days from inoculation to spore release. If conditions are unsuitable, it may be extended to 2-3 months, or even fail to form a cap. At this stage, temperature, humidity, and ventilation must be controlled and ensured. Temperature should be controlled at around 28°C; relative humidity at 70-90%; diffused light is preferable, avoiding direct sunlight; Lingzhi is relatively sensitive to carbon dioxide, and during the cap formation stage, windows need to be opened regularly every day for ventilation. Ventilation should be carried out slowly to avoid abnormal growth of Lingzhi caused by sudden changes in temperature and humidity.

2. Pest and Disease Control

(1) Penicillium. The pathogen is a type of ascomycete fungus. Slant cultures, wheat bran dish seeds, mycelium in bottles, stipes, and caps can all be infected by it. After harvest, it is also the main harmful agent during storage. Control methods: when mold infection occurs, strengthen indoor ventilation and reduce relative humidity without affecting the growth of Lingzhi. Severely infected bottles should be promptly removed, discarded, and disinfected. Alternatively, use a burned blade to dig out the contaminating fungi, then spray with a 1000-fold dilution of 5% benzalkonium bromide for sterilization.

(2) Mucor and Rhizopus. These are two types of algal fungi among the fungi. They often infect wheat bran dish seeds and mycelium in the early stage of bottle cultivation. In hot and humid seasons, when bottle plugs are damp and aseptic technique is not strict, they often cause damage, inhibiting mycelial growth and deteriorating the culture medium. Control methods are the same as for Penicillium.

(3) Mushroom gnats and Sciaridae gnats. Both belong to the order Diptera, family Mycetophilidae. The larvae of mushroom gnats bore into and feed on young mushroom buds,

stipes, and growing caps; at the slightest disturbance they burrow into the Lingzhi tissue. They cocoon and pupate on the fruiting body and emerge as adults. Control method: hang gauze strips soaked in dichlorvos indoors.

III. Harvest and Processing

After spore release, when the edge of the cap no longer grows (no pale white edge, and no longer thickens), the Lingzhi fruiting body is mature and can be harvested and shade-dried, or dried at 40-50°C. If spore powder is to be collected for medicinal use, cover the cap with a paper bag to prevent spores from escaping, and a relatively large amount of spore powder can be collected. The period during which the fruiting body releases spores can last about one month.