Application of the Year-round Cultivation Technology of Mulberry Branch Edible Fungi in Jinxiu Dayaoshan

Li Fasheng, Zeng Weiming, Li Huai, He Dachong

(Institute of Biology, Guangxi Academy of Sciences, Nanning, Guangxi 530003)

Jinxiu is located between 109°50′-110°27′ east longitude and 23°40′-24°28′ north latitude. The county's forest area is (2.00×103) km2, with a forest coverage rate of 87.34%, of which the water-source forest area is (7.06×103) km2. It has 4 titles: the largest water-source forest protection area in Guangxi, the national-level demonstration county at the source of the Pearl River Basin shelterbelt construction, Dayaoshan National Forest Park, and Dayaoshan National Nature Reserve. Within the county there are 26 rivers with a catchment area of more than 10 km2, which support the production water use of more than 2 million people in nearby Laibin City, Liuzhou City, Wuzhou City and other areas as well as irrigation water for (1.00×104) km2 of cultivated land, with an annual output of (2.5×109) m3 of water. It can thus be seen that its ecological protection is extremely important, but this sharply conflicts with the contradiction that Jinxiu forest farmers rely on cutting trees as their main source of income.

Since 2008, this institute has undertaken the Jinxiu Dayaoshan edible fungi year-round cultivation technology research and demonstration key project assigned by the regional science and technology department. Through several years of experimental research, it has been proven that the specific environmental and climatic conditions of Jinxiu Dayaoshan are quite suitable for year-round cultivation of edible fungi.

1 Climatic characteristics

Jinxiu belongs to the southern subtropical monsoon climate zone, with obvious seasonal climate changes. The altitude in the mountains is not less than 700 m, with significant subtropical mountain climate characteristics, namely warm winters and cool summers, many cloudy and rainy days, little sunshine, high humidity, and relatively obvious vertical and horizontal changes in climate. The multi-year average sunshine duration is 1269 h, accounting for 29% of the possible sunshine duration. The multi-year average temperature is 17℃, the average temperature of the hottest month (July) is 28.5℃, the average temperature of the coldest month (January) is 8℃, the annual frost-free period is 283 d, the multi-year average rainfall is 1648 mm, the annual average number of rainy days is 190 d, and the rainy season is distributed from May to August. The multi-year average relative humidity is 83%, the annual dryness of the county seat is 0.66, evaporation is less than rainfall, and the air is humid. Wind direction changes obviously; generally there are more northerly winds in winter, with an average frequency of 27%, and more southerly winds in summer, with an average frequency of 33%. Spring and autumn are periods when northerly and southerly winds alternate. The monthly average temperatures of Jinxiu in the past 10 years are shown in Table 1.

2 Year-round cultivation technology

2.1 Variety and seasonal arrangement

The environmental and climatic conditions in the Jinxiu mountains are suitable for the cultivation of many edible and medicinal fungi such as shiitake, lingzhi, wood ear, Jinfu mushroom, shaggy mane, Pleurotus species and so on, but years of experiments have proven that when using mulberry branch wood as the main substrate to cultivate shiitake and straw-rotting fungi (Jinfu mushroom, shaggy mane, etc.), the fruiting effect is relatively poor. Therefore, according to factors such as the climatic characteristics of Jinxiu, the monthly temperature variation pattern, the cultivation substrate and its sources, geographical and cultural conditions, as well as the temperature-type characteristics of edible fungi and marketable varieties, the varieties and fruiting season arrangements for realizing year-round cultivation of edible fungi in Jinxiu Dayaoshan are shown in Table 2.

Table 2 shows that the fruiting (wood ear) periods are selected as Baiyun No. 6 for spring and autumn, Taimao No. 1 for summer, and enoki mushroom for winter.

2.2 Making of fungus bags

Because the air humidity in Jinxiu Dayaoshan is relatively high, it brings certain difficulties to bag making, so the production of fungus bags is very critical.

2.2.1 Time arrangement

Baiyun No. 6: early January and mid-July; Taimao No. 1: early April; enoki mushroom: mid-October.

2.2.2 Process flow

Raw materials→crushing→adding water→piling overnight→auxiliary materials→mixing evenly→adjusting moisture and pH→bagging→sterilization→cooling→inoculation→mycelium cultivation.

2.2.3 Operation key points

(1) Raw materials and crushing

The main raw material is mulberry branch wood, sourced from a mulberry and silkworm production area about 45 km away. It is crushed through a 6 mm-8 mm diameter screen into mulberry branch sawdust for later use.

(2) Formula

Cultivation material formula for Baiyun No. 6 and Taimao No. 1: mulberry branch sawdust 90%, wheat bran 5%, corn flour 3%, gypsum 1%, lime powder 1%, water 170%, initial pH 7.5-pH 8.0; cultivation material formula for enoki mushroom: mulberry branch sawdust 85%, wheat bran 10%, corn flour 3%, gypsum 1%, lime powder 1%, water 170%, initial pH 7.5-8.0.

(3) Moistening with water

According to the actual amount of material input, weigh mulberry branch sawdust in proportion, add the corresponding amount of water and lime powder, stir evenly, build a pile, cover with film, and moisten the material overnight.

(4) Mixing materials

Spread out the material pile, add auxiliary materials (wheat bran, corn flour, and gypsum pre-mixed evenly), and after fully and evenly stirring, check the water content and pH. The water content check is generally appropriate when the material is gripped firmly by hand and water seeps out between the fingers but does not drip; if it does not meet the requirement, adjustment is needed.

(5) Bagging

Use 17 cm×33 cm fungus bags and fill them separately with a stamping-type bagging machine. Moderate tightness is required. Generally each bag holds about 1.1 kg of wet material. Insert the inoculation stick and put on a cotton-free cover body; cotton plugs should not be used.

(6) Sterilization

Either atmospheric pressure or high pressure can be used, but no matter which method is used, the fungus bags should be placed in layers in the pot to facilitate uniform steam penetration. Under this precondition, the sterilization parameters are as follows: atmospheric pressure sterilization: start timing after large steam appears for 4 h (at this time the material temperature reaches 100℃), maintain for 15 h, stop the fire, simmer overnight (about 18 h), then open the pot; high pressure sterilization: operate according to the operating procedures of the high pressure sterilization pot, maintain 0.15 MPa for 3.5 h, cut off the power, and open the pot after the pressure in the pot naturally drops to zero.

(7) Inoculation

After sterilization is completed, promptly move the fungus bags into the pre-cooling room, force-cool until the material temperature is 30℃-35℃, then send them into the inoculation workshop. Use aerosol and simultaneously turn on ultraviolet lamps to disinfect the space and the surface of the fungus bags for 3 h. After that, inoculation personnel pass through the buffer passage and change into special inoculation clothing before entering the inoculation workshop, and are required to carry out inoculation strictly according to aseptic operation. During inoculation, pull out the inoculation stick, let the spawn fall naturally into the hole, and then seal the material surface with a layer of spawn.

(8) Cultivation

After inoculation is completed, send the fungus bags into the cultivation room, turn on the air conditioner, maintain the indoor temperature at (26±1)℃ and humidity at about 65%, and cultivate the mycelium in the dark for 25 d-30 d. After the mycelium has completely covered the cultivation material and then undergone a 10 d-15 d post-ripening period, it can enter fruiting management.

2.3 Management of fruiting (mushroom)

The requirements for fruiting facility conditions are relatively simple; a simple shed with a bamboo and wood structure that can shade sunlight and block wind and rain is sufficient.

2.3.1 Baiyun No. 6 and Taimao No. 1

Promoting wood ear buds: remove the cotton-free cover body from the fungus bags, tighten the bag opening, disinfect the surface with 0.1% potassium permanganate solution, then use a hole puncher with a diameter of 5 mm, length of 15 mm, and spacing of 50 mm to make fruiting holes, then place them upside down in a zigzag arrangement on a bed surface that has been leveled and treated with insecticide and disinfection, with a distance of about 200 mm between bags, and cover with a film with good light transmittance. Starting from the 4th day, uncover the film once in the morning and once in the evening each day for 30 min each time, and shake off the condensed water on the film. Starting from the 7th day, wood ear buds begin to appear, and by the 13th d-15th d, the wood ear buds have basically opened into sheets, that is, they enter the stage of wood ear sheet growth management; wood ear management: during the fruiting period, the main task is water management. Under the condition of ensuring sufficient aeration and light, sufficient water should be ensured, and the water quality should be clean and hygienic, meeting drinking water standards. The number of waterings and the duration depend on the state of the wood ear sheets. When the temperature is not lower than 18℃, generally water once in the morning and once in the evening each day, each time until the wood ear sheets fully unfold, similar to the state of dry wood ear fully soaked with water. When watering, doors and windows should be opened, films lifted, etc., to maintain good ventilation in the environment; harvesting: when the wood ear sheets are fully unfolded and can be picked easily (without effort), it proves that the wood ear sheets have matured and should be harvested in time. Under normal temperature and normal management, from promoting wood ear buds to harvesting the first batch generally takes about 30 d. Baiyun No. 6 can generally harvest 2-3 batches over about 2 months, and Taimao No. 1 can generally harvest 3-4 batches over about 3 months.

2.3.2 Enoki mushroom

Remove the cotton-free cover body from the fungus bags, straighten the bag opening, and scrape off the old mycelium on the surface of the cultivation material, which is called scratching. After new mycelium grows out, cover the bag opening with newspaper, spray water on it, then cover the newspaper with a layer of film to keep the newspaper moist. Under conditions of 12℃-13℃ and humidity 80%-85%, after 4 d-10 d, mushroom buds appear. When the temperature reaches 5℃-8℃, lift the film around the shed and let cold wind blow for 2 d-3 d, then carry out normal fruiting management. By adjusting the film around the fruiting shed to maintain a temperature of about 10℃ and humidity of 80%-85% inside the shed, high-quality enoki mushrooms can be cultivated. When the stipe length reaches about 13 cm-15 cm and the cap has not opened, they can be harvested. After harvesting, still scratch the material surface, then manage conventionally to produce the next batch of mushrooms. Under normal circumstances, generally 3 flushes of mushrooms can be harvested over about 2 months. The fruiting (wood ear) scene of large-scale cultivation demonstration with mulberry branch sawdust is shown in Figure 1.

3 Summary and discussion

Through several years of experimental research, a year-round cultivation technology for edible fungi suitable for Jinxiu Dayaoshan has been summarized and formed, including variety combination, cultivation substrate, fungus bag production, fruiting management and other contents. The fresh wood ear (mushroom) biological conversion rate of the large-scale demonstration reached: Baiyun No. 6 (average of 2 seasons) 125.74%, Taimao No. 1 139.04%, enoki mushroom 126.24%. The highest input-output ratio reached 1:3.67 (enoki mushroom), and the lowest reached 1:1.87 (hairy wood ear), with an average of 1:2.89. The economic benefit is remarkable, and the quality of the mushroom products produced is excellent. Jinxiu Dayaoshan is known for its pristine ecological environment and is rich in ecotourism resources, so it is not suitable to develop industrial products. Therefore, using the by-product of the sericulture industry, mulberry branch wood, for year-round cultivation of edible fungi not only gives forest farmers a normal economic reliance, but also provides an important guarantee for a more eco-friendly environment. To achieve sound development of year-round cultivation of mulberry branch edible fungi in Jinxiu Dayaoshan, relevant departments still need to provide support in policy, system, funding, personnel and other aspects, introduce suitable operation models such as company + farmers + base, and build a unique organic edible fungus brand of Jinxiu Dayaoshan.