(1) Mycelium is germinated from spores. Under artificial culture conditions, hyphae are usually white and fluffy, with diaphragms and branches, and many hyphae gather together to form mycelium. Different from other edible fungi, a large number of unicellular pollen spores (also called conidia) will be formed when the mycelium grows to a certain stage, which can germinate into mononuclear hyphae or binuclear hyphae under suitable conditions. It was found in the experiment that the number of pollen spores in the mycelium stage of Flammulina velutipes was related to the quality of Flammulina velutipes. The strains with more pollen spores had poor quality and the base of the stalk was darker. ?
(2) The main function of fruiting body is to produce spores and reproduce offspring. The fruiting body of Flammulina velutipes consists of cap, pleat and stalk, most of which grow in bundles, and the meat is soft and elastic. The cap is spherical or oblate, with a diameter of1.5 ~ 7 cm. It is spherical when it is young, and gradually spreads out. When it is over-mature, the edge folds upward. There is a thin layer of colloid on the surface of the cap, which is sticky when wet, yellow-white to yellow-brown, white in meat, thick in the center, thin in edge, white or ivory in pleat, sparse, different in length, and free or curved from the stalk. The stipe is central, hollow and cylindrical, slightly curved, with a length of 3.5 ~15cm and a diameter of 0.3 ~1.5cm. The stipe is connected at the base, the upper part is fleshy, the lower part is leathery, and the surface is densely covered with dark brown short fluff. The basidiospores are born on the solid layer of the fungus pleats, and the spores are cylindrical and colorless. ?
2. Growth and development conditions?
(1) Nutritional Flammulina velutipes is a saprophytic fungus, which can only absorb nutrients from ready-made culture materials through mycelium. In cultivation, the selection of culture materials has great influence on yield and quality. The nutrients needed for the mycelium growth and fruiting body development of Flammulina velutipes include nitrogen nutrition, sugar nutrition, mineral nutrition and a small amount of vitamins. ?
Nitrogen nutrition is the raw material for Flammulina velutipes to synthesize protein and nucleic acid. In the cultivation ingredients, wheat bran, soybean powder and other raw materials contain a lot of nitrogen nutrients. Sugar mainly refers to carbohydrate, which is the energy source of Flammulina velutipes' life activities and the main component of cells. Flammulina velutipes can make use of starch, cellulose and lignin in the culture medium. In the mycelium growth stage, the ratio of carbon to nitrogen in the culture medium is 20∶ 1, and in the fruiting body growth stage, it is 30 ~ 40 ∶1. Flammulina velutipes needs mineral elements such as phosphorus, potassium, calcium and magnesium, so a certain amount of mineral nutrients such as potassium dihydrogen phosphate, calcium sulfate and magnesium sulfate should be added in the culture. Flammulina velutipes also needs a small amount of vitamins. Because the amount of vitamins contained in culture materials such as wheat bran and soybean powder can basically meet the needs of Flammulina velutipes, vitamins are often not added in cultivation. ?
(2) Temperature Flammulina velutipes is a low-temperature fruiting fungus, and its mycelium can grow in the range of 5 ~ 32℃, but the optimum temperature is 22 ~ 25℃. The mycelium is resistant to low temperature, but weak to high temperature, and stops growing or even dies above 34℃. The fruiting body differentiation was carried out in the range of 3 ~18℃, but the optimum temperature for its formation was 8 ~10℃. Flammulina velutipes grows vigorously at low temperature, but the temperature is high, with slender handle and small lid. At the same time, Flammulina velutipes can stimulate the primordia of fruiting bodies when the temperature difference between day and night is large. ?
(3) In the growth stage of hyphae with water content, the water content of the culture medium should be 65% ~ 70%, below 60%, the hyphae will grow poorly, and above 70%, the oxygen in the culture medium will decrease, which will affect the normal growth of hyphae. At the stage of primordium formation, the relative humidity of air in the environment is required to be about 85%. In the growth stage of fruiting body, the relative humidity of air should be kept at about 90%. When the humidity is low, the fruiting body can't grow fully, and when the humidity is too high, pests and diseases are easy to occur. ?
(4) Flammulina velutipes is an aerobic fungus, which needs to absorb fresh air continuously during its metabolism. In the mycelium growth stage, micro ventilation can meet the needs of mycelium growth. A large amount of oxygen is consumed during the fruiting body formation period, especially when it is cultivated in large quantities. When the accumulation of carbon dioxide concentration in the air exceeds 0.6%, the formation of fruiting body and the development of mushroom cap will be inhibited. ?
(5) Both hyphae and fruiting bodies can grow in complete darkness, but when the fruiting bodies are in complete darkness, the growth of the cap is slow and small, and more deformed mushrooms are formed. Weak scattered light can stimulate the growth of the cap, while excessive light can inhibit the growth of the stipe. Flammulina velutipes, which mainly eat stalks, can be shaded by paper tubes during its culture to promote the elongation of stalks. ?
(6) The pH of Flammulina velutipes requires acidic environment, and the mycelium can grow in the range of pH 3～8.4, but the optimum pH value is 4 ~ 7, and the optimum pH value is 5 ~ 6 in the fruiting body formation period.