Mushroom soft delicate white fruit body of fleshy fungi, of the family Agaricaceae. The real plant is the microscopic fine thread-like body called mycelium, grows on the substratum or under the surface of soil. After maturity the mycelia come together in a very compact form and sprout as spreading umbrella like structure. Majority of mushroom belong to Hymenomycetes of Basidiomycotina, characterized by the presence of spore bearing hymenium layer below the spreading structure, the gill.
The poisonous mushrooms are commonly known as toadstools. Sometimes a species may be edible when it is young and fresh, may become poisonous or inedible when it is overmatured and has started decaying. The common edible mushroom belongs to some species of Agaricus and Pleurotis. The common poisonous species are of Lepiota and Amanita. Edible mushrooms provide a good addition to the diet in the form of proteins, carbohydrates, valuable salts and vitamins, immediate between meat and vegetables. Due to high protein and mineral contents and low caloric value, it is recommended to heart patients. About 20 mushroom species grow wild in Bangladesh, of which 5-6 are poisonous. Some mushrooms grown wild are eaten by the tribals of the chittagong hill tracts. Very recently some small-scale farms are cultivating mushroom in the country.
Mushroom cultivation 'Raising edible mushroom for human consumption. In the ancient Greek, Roman and Indian culture mushroom has been described as delicacies associated with royal class. The commercial cultivation first started in Europe with the beginning of this century. Mushroom cultivation in Bangladesh is very recent. In early 1980s commercial mushroom cultivation was initiated by Bangladesh Agricultural Research Council and then a Mushroom Culture Centre at Savar. The recommended cultivated mushroom is white button mushroom (Agaricus bisporus) and oyster mushroom or wood fungus (Pleurotis sajor-caju, P. flabellatus, P. ostreatus).
The oyster mushroom is common and favourite in Bangladesh. The main raw material for growing is a composite mixture of rice straw and rice husk, saw dust and cotton waste, and some other agro-residues. It is grown in the polythene chamber in thatched hut or in pucca house. The whole process requires about 35 days. After planting, harvest is done in 10-15 days. It is cultivated throughout the year but the oyster mushroom is cultivated in winter season. For cultivation of pure mushroom, spawn or seed (spore) is essential. The temperature required for good growth is 20°-25°C at the beginning and 10°-18°C at the fruiting stage. Harvesting is done at the early stage of fruiting just before the spreading of umbrella-like fruit body. From a single cultivation bed continuous harvesting is done up to two weeks. The bed can be recycled to some extent. The fruit body is taken fresh or dried for long preservation.
The paddy straw mushroom is summer type (Volvariella diplasia, V. volvacea and V. esculanta). The requirements for the culture bed are more or less similar to that of oyster mushroom but the temperature needs to be 35°-40°C. At present the production cost is about Tk 50-60 and the market value is about Tk 150-200 per kg. [Mostafa Kamal Pasha]