1. Introduction
A model scheme for cultivation of Oyster mushroom (Pleurotus spp.) with commercial viability and bankability has been prepared keeping in view the agro-climatic conditions and other related aspects for successful cultivation of the mushroom and its subsequent marketing. Cultivation of mushroom can be taken up on a large scale by individual entrepreneurs. The agro-climatic conditions as well as local availability of raw material makes mushroom cultivation an economically viable proposition.
Mushrooms, also called ‘white vegetables’ or ‘boneless vegetarian meat’ contain ample amounts of proteins, vitamins and fibre apart from having certain medicinal properties. Mushroom contains 20-35% protein (dry weight) which is higher than those of vegetables and fruits and is of superior quality. Mushrooms are now getting significant importance due to their nutritional and medicinal value and today their cultivation is being done in about 100 countries. At present world production is estimated to be around 5 million tonnes and is ever increasing. Though 20 mushroom varieties are domesticated about half a dozen varieties viz; button, shitake, oyster, wood ear and paddy straw mushrooms contribute 99% of the total world production.
Mushroom offers prospects for converting lignocellulosic residues from agricultural fields, forests into protein rich biomass. Such processing of agro waste not only reduces environmental pollution but the by product of mushroom cultivation is also a good source of manure, animal feed and soil conditioner.
2. Cultivation of Oyster Mushroom
The cultivation of Oyster mushroom or Dhingri mushroom or Pleurotus spp is relatively simple and can be a homestead project. The agro- climatic conditions in our country especially in the North Indian States are conducive for mushroom cultivation when the temperature is 15-30oC and relative humidity is 70-80%. The production decreases during peak periods of winter.
2.1 Climate & other conditions
Pleurotus spp. is one of the choice edible mushrooms which can be cultivated in the tropics. It has gained importance only in the last decade and is now being cultivated in many countries in the subtropical and temperate zones. Different species of Pleurotus are suited for growing within a temperature range of 15 to 30oC. P.sajor-caju can tolerate temperatures upto 28-30oC, although it fruits faster and produces larger mushrooms at 25oC during the cooler months of the year or in the highlands of the tropics. This is the species now popularly grown in the tropical Southeast Asian countries, including India. P.abalonus prefers lower temperatures of 22-24oC and is most popular among the Chinese. P.ostreatus is the so-called low-temperature Pleurotus, fruiting mostly at 12-20oC. This species is more suited to the temperate climates of Europe and the United States, although many growers in the USA are also producing P.sajor-caju.
In Europe it is known as the oyster mushroom (P.ostreatus) while in China it is called the balone mushroom (P.abalonus or P. cystidiosus). Several other species are now available for cultivation. These are P.sajor-caju, P.florida (probably a variant of P.ostreatus), P.sapidus, P.eryngii, P. columbinus, P.cornucopiae, and P.abellatus.
2.2 Substrate
Like other mushrooms, Pleurotus spp. can be grown on various agricultural waste materials using different technologies. They grow well on different types of lignocellulosic materials, converting them into digestible and protein-rich substances suitable for animal feeds. Pleurotus spp. may be produced in the tropics on a mixture of sawdust and rice bran, rice straw and rice bran, saw dust and ipil-ipil leaves and other combinations of tropical wastes. Other wastes such as corncobs, cotton waste, sugarcane bagasse and leaves, corn leaves, grasses, rice hulls and water hyacinth leaves are also good substrates for growing this mushroom (Quimio, 1986). The substrates used in each region depend upon the availability of agricultural wastes.
2.3 Preparation of substrate - Sterilization / Pasteurization
The use of a pressure cooker to sterilize Pleurotus substrate is not recommended since sterilization kills beneficial micro organisms which are present in the substrate, as well as the harmful ones. In addition, nutrients in the compost are broken down by sterilization into forms more favorable for the growth and development of competing micro organisms (FAO, 1983). Thus, substrates that are sterilized are easily contaminated unless spawned under very aseptic conditions, as in media and spawn preparation.
Steaming at 100oC (pasteurisation) is more acceptable because the cost is lower (the steamer may only be an ordinary large-capacity casserole or a drum) and substrates thus steamed are less susceptible to contamination. The substrate is steamed for 2-3 hours, depending on the volume and the size of the bags. When using a lower temperature (60-70oC) as in the case of room or bulk pasteurisation, the substrates, whether in bulk or already packed in bags, are steamed for at least 6 to 8 hours.
2.4 Inoculation / Spawning
Spawning is carried out aseptically, preferably using the same transfer chamber or the same inoculation room as is used in spawn preparation. Grain or sawdust spawn is commonly used to inoculate the substrate in bags. With grain spawn, the bottle is shaken to separate the seeds colonized with the white mycelium. After lifting the plug and flaming the mouth of the bottle, a few spawn grains (about 1 to 2 tsp.) are poured into the substrate bag. Both the plug of the spawn and the plug of the compost bag are replaced and the next bags are then inoculated. The newly inoculated bags are slightly tilted to distribute the grains evenly in the shoulder area of the bag around the neck.
For sawdust spawn, the spawn is broken up with an aseptic needle. A piece of the spawn may then be transferred, using a long flat-spooned needle especially designed to scoop the spawn. One bottle of grain or sawdust spawn in a 500 ml dextrose bottle is sufficient to inoculate 40 to 50 bags.
The highly industrialized method involves bulk-pasteurisation and bulk-spawning before the substrates are distributed in beds similar to those used for Agaricus. The system is labour-saving but requires more complex equipment. Bulk material processing and handling are highly risky for tropical mushroom cultivation due to the risk of contamination.
2.5 Incubation
The spawned compost bags are kept in a dark room until the mycelium has fully penetrated to the bottom of the substrate. In 20 to 30 days, depending upon the substrate/substrate combination, the substrate appears white, due to the growth of the mycelium. The bags are kept for an additional week before they are opened to check that the mycelium is mature enough to fruit. Most strains of the mushroom form primordia after 3 to 4 weeks of mycelial growth. The bags are opened, to initiate fruiting, inside a mushroom house.
2.6 Fruiting
The size of the mushroom house will depend on the number of bags prepared at any one time. The house may be built of nipa, sawali, wood or concrete. Air vents on the upper walls will provide the ventilation required for the development of the sporocarps. At the same time a small amount of light should be provided inside the house. The walls may be covered with plastic or foam sheets to increase the relative humidity (80-95%) in the production house. Shelves, made from bamboo or wood, line both sides of the house. The shelves are on bamboo frames, one shelf above the other, with about 40-50 cm space between them. They should be strong enough to hold the bags or blocks containing the compost.
The bags are opened by removing the plug and then rolling down the mouth of the bag. Alternatively, the mouth portion may be cut off with the help of a sharp instrument or the bag may be slit either criss-cross at four to six places or simply slashed lengthwise. When following the latter technique, the bags may be suspended with a rope or string. When using blocks instead of bags, the blocks are opened either completely or with only the surface or upper portions exposed.
Fruiting requires an appropriate temperature range (20-28oC), ventilation, light moisture and humidity (80-95%). To provide moisture, daily watering of the substrate is required but excessive watering should be avoided. If the temperature inside the house rises to more than 30oC, a light water mist should be used to lower the temperature and hasten fruiting. Doors and windows may also be opened, especially at night to keep the area cool.
Approximately 3 to 4 days after opening the bags, mushroom primordia will begin to form and mature mushrooms would be ready for harvesting in the following 2 to 3 days. If the substrate is not fully colonized, the onset of fruiting is likely to be delayed.
To harvest the mushrooms, they are to be grasped by the stalk and gently twisted and pulled. A knife should not be used. If kept in a refrigerator or in a cool place, the mushrooms can remain fresh for up to 3 to 6 days. After harvesting from the top end of the bag, the other end may be opened to allow fruiting. The two ends are sometimes opened and allowed to fruit at the same time. After harvesting from the end portions, slits may be made on the central portion of the bag so that more mushrooms can develop. When a sawdust substrate is used, the harvested surface may be scraped lightly to expose a new surface for fruiting. As long as the substrate appears white, mushrooms will continue to form under adequate environmental conditions. When it appears colourless and soft, it is time to remove the bags from the house.
2.7 Yield
Yield ranges from about 100-200% of the dry weight of the substrate and depends on the substrate combination as well as the way in which the substrate has been managed during the fruiting season. The richer the combination and the whiter and denser the mycelium, the greater will be the mushroom yield.
To increase yield, the most common supplement used is urea or organic fertilizer dissolved in water (100 gm in 100 liters water). Using a plastic mist sprayer, the solution is sprayed on the surface immediately before fruiting.
3. Marketing
Mushroom has a good overseas market in which the present contribution of India is negligible. In the domestic market the availability of mushroom is limited to cities and big towns only. Mushrooms can be marketed either fresh or after dehydration. There is huge international demand for dried mushroom and the farmers can get better returns by tapping these sources.
4. Financial aspects
4.1 Unit cost
In the present model, the unit cost for production of 1000 kg of oyster mushroom per cycle works out to Rs.37000/-. The details of the project cost and techno economic parameters are presented in Annexure I & II respectively. This may be modified to suit the local conditions taking into account the different techno-economic parameters prevailing in the locality.
4.2 Margin money
The margin money / down payment prescribed is 5 %, 10 % and 15% for small, medium and other farmers respectively. The rest of the cost of development will be provided as bank loan. However, in the present model, 10 % of the unit cost i.e. Rs.3700/- has been considered as margin money
4.3 Bank loan
Bank loan of 85 - 95 % of the total cost of development shall be available from the financing institution. Bank loan considered in the model is 90%. It works out to Rs.33300/ha in the model.
4.4 Rate of Interest
Banks are free to decide the rate of interest within the overall RBI guidelines. However, for working out the financial viability and bankability of the model scheme, we have assumed the rate of interest as 12% p.a.
4.5 Security
Banks are guided by RBI guidelines issued from time to time in this regard.
4.6 Financial analysis
The financial analysis has been done considering the income from the sale of fresh mushroom. The scheme is financially viable. The finanical indicators are :
NPV : Rs.31269
BCR : 1.15 : 1
IRR : > 50%
The details are furnished in Annexure III.
4.7 Repayment schedule
The bank loan along with the interest can be repaid within 6 years including 1 year of grace period. The details are furnished in Annexure IV.
5. Conclusion
Oyster mushroom has good nutritional potential and has wider accepatance in Indian markets. Hence, the banks can extend necessary assistance for the promotion of this scheme.
Oyster Mushroom Annexure I
Oyster Mushroom Annexure II
Oyster Mushroom Annexure III
Oyster Mushroom Annexure IV
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