Everything you need to know about mushroom cultivation. Learn about how to cultivate different types of mushroom:- 1. Button Mushrooms 2. White Button Mushroom 3. Oyster Mushroom 4. Milky Mushroom.
1. How to Cultivate Button Mushrooms?
Of the various types of mushroom presently cultivated in the world, the eight, i.e., button, oyster, straw, shikate, woody ear, winter, silver ear, and nameko, are commercially important, and these account for 99% of the total world mushroom production.
In India, only three types, viz. button, oyster, and straw, mushrooms are commercially cultivated.
The present model is on button mushroom (Agaricus bisporus), which accounts for 90% of India’s production of mushrooms. About 38% of the total world production of mushrooms is button mushroom.
The spawn is mushroom seed, and in the mushroom industry, it means the planting material, which consists of the vegetative stage of the mushroom (mycelium) and its substrate. The success of mushroom cultivation and its yield depend to a large extent on the purity and quality of the spawn used. Now a days, highly sophisticated, specialized, and mechanized commercial spawn making system have been developed, and online global marketing is done.
(a) Raising and maintenance of pure culture
(b) Master spawn preparation
(c) Commercial spawn production
The preliminary requirement for making spawn is to obtain a pure culture of the desired mushroom species on a suitable medium, which is used for spawn preparation.
Pure culture of mushroom mycelium can be raised by either tissue culture or spore culture raised from single or multi-spores collected from healthy, robust and of desired characters mushroom. The cultures are retrieved periodically for maintaining vigour and growth. For long-term storage of cultures, these are preserved by specific methods. The pure cultures can also be procured from reputed laboratories, which are engaged in the production of spawn.
Wheat or other cereals grains are used as substrate for mushroom spawn production. In India, wheat grains are generally used for the preparation of mushroom spawn. Well cleaned, dust and weed-seed free wheat grains are washed in clean preferably chlorinated water and boiled in water (1 : 1.5 w/v) for 20 minutes, left for another 10-20 minutes in the same hot water without boiling, and then, excess water is drained out by putting the contents on a wire mesh.
This is done for having moisture content of grains around 50% and also to make them soft for mycelium growth. After cooling and surface drying of the boiled grains, the gypsum 2% and calcium carbonate 0.5% (on dry weight basis) are added to these grains and mixed thoroughly. This will help to maintain the pH of the substrate and also to prevent sticking and clustering of grains. The substrate is now filled in clean wide mouthed empty glucose, milk bottles, or polypropylene bags, and plugged with non-absorbent cotton.
These are then sterilized at 22 lbs psi pressure for 2 h in an autoclave, which will kill the contaminants present in the substrate. After cooling, these are inoculated with culture bits from pure culture of mushroom growing in Petri-plates/media slants and incubated at 25±1°C. During incubation, these bottles or polypropylene bags are shaken at weekly interval and kept for complete colonization of grains by the mycelium. As such, the master spawn is ready for use in 25-30 days.
Similarly, autoclaved grains in polypropylene bags are inoculated with master spawn and incubated at same temperature. From one bottle of master spawn, 25-30 bags can be inoculated to prepare commercial spawn. Likewise, the commercial spawn becomes ready in 10-15 days, and it is further used for planting/spawning. All inoculation work is carried out under aseptic conditions in the inoculation room, and strict hygiene is maintained in the spawn laboratory.
While selecting the site for mushroom cultivation, some important factors to be taken care of are the availability of clean water, raw materials, and vicinity to the market. If mushroom cultivation is done on large scale, the proximity of site should be near the road to bring the raw materials and for sending of produce to the market. Power supply and availability of labour are also necessary. Implements required for seasonal cultivation are few agricultural implements, which are generally available with the farmers.
These are forks for turning the heap, buckets, tubs, spray pumps, polyethylene sheets, gumboots etc. The seasonal growing structures are simple cropping rooms/sheds, which can be a thatched structure erected on a bamboo frame covered with plastic sheets, old gummy bags, paddy straws etc. The cultivation rooms can be made of mud or mud and bricks, or cement and bricks. No insulation is required for seasonal growing rooms/structures.
The mushroom houses made with iron pipes/angles frame and synthetic fiber cloth material/plastic sheet both inside and outside with cereal straw insulation in between is also good for seasonal cultivation. If a brick structure is to be erected, its direction should be east west, and exhaust vents should be provided opposite to each other preferably a foot above the ground level. The exhaust vents or windows should be covered with wire net to avoid rats.
2. How to Cultivate White Button Mushroom?
The cultivation technique of white button mushroom involves four major components, viz. composting, spawning, casing, and care during cropping.
This mushroom requires an indoor temperature between 15° and 25°C, however, more minutely, 22-25°C for the completion of vegetative growth and 14-18°C for the development of fruiting bodies. In northern India, it can be grown conveniently from October to February under natural conditions.
Like other fungi, Agaricus bisporus is heterotrophic organism and requires readymade food for its growth. It requires carbon, phosphorus, potassium, sulfur, iron, and vitamins such as thiamine and foline for its growth. passage
In nature, mushrooms get nourishment from the soil if saphrophytic, while some other mushrooms parasitize in host and mycorrhizal mushroom grows in mycorrhizal association with plant roots.
All the ingredients that contain the requisite compounds are mixed in a fixed proportion and fermented (decomposed) in a set pattern to form a substrate, which is selective in nature for supporting the growth of Agaricus mycelium. This substrate is called compost and process of fermentation or decomposition in a set pattern is called composting.
The decomposition process is governed by a number of microorganisms, which produce important biochemical reactions, thereby making it selective for Agaricus at the practical exclusion of other competing microorganisms.
The compost is prepared by mixing various raw materials (wheat/paddy/Brassica straw) in specific proportions either by long or short method of composting. Preparation of compost by short method requires specialized unit, which is not feasible for small and marginal farmers, hence, only long method, which takes 28 days and involves 7-8 turnings at varying intervals, is being used.
For the preparation of compost, different formulations are being used. The wheat straw can be replaced by paddy or Brassica straw depending on the formula to reduce the cost of cultivation.
Clean and dry straw should be spread on a concrete floor and wetted with water for 48 h. However, there should be no run-off of water during wetting. A neat and clean hard surface may be used if a concrete floor is not available.
Turning Schedule:
0 + 6 +10 + 13 + 16 + 19 + 22 + 25 + 28 days
On 28th day, the compost is tested for ammonia and moisture content (70%). There should be no ammonia smell in the compost. For checking moisture content, a small amount of compost is taken in the palm and squeezed. Water should come between the fingers but it should not fall down.
If there is any ammonia smell or water content is more in the compost, the heap should be exposed for a little longer duration turnings, and one or two turnings on alternate days may be given. The seasonal growers cannot afford the construction of pasteurized chambers, hence, chemical pasteurization using carbendazim + formaline is followed since it is cost effective, and it reduces the incidence of insect-pests and diseases.
Spawn (mushroom seed) is available in polypropylene bags, thus, a single bag containing 500 g spawn is sufficient for 100 kg ready compost. After mixing spawn in compost (when its temperature is around 25°C), it is either filled in polyethylene bags or is spread on the racks, and thereafter, it is covered with old newspapers or polyethylene sheets, which have been sprayed with 2% formaline depending upon the temperature prevalent in mushroom house.
The room temperature is maintained at 22-24°C and humidity 80-90% by spraying water on the newspapers, walls, and roof of the mushroom house. The height of compost in the racks should be 15 cm, whereas, in bags, it should be 25-30 cm irrespective of the size.
Generally, a mixture of farmyard manure and garden/field soil is used but a mixture of burnt rice husk and garden/field soil (1:1) has been found to be the cost-effective. As the burnt rice husk needs no sterilization, only the garden/field soil is sterilized by formaline.
After removing polyethylene sheets or newspapers covering compost, a layer of 2.5-3.5 cm of this mixture is spread on the compost. Casing should be done, when there is thorough/complete spawn run in the compost, and after casing, water is to be sprayed on the racks/bags.
Maintenance of Environment in Mushroom House:
Temperature around 22-24°C till one week after casing is most desirable, and subsequently, the temperature should be 14-18°C and relative humidity of 80-90% in the mushroom house during entire fruiting period. Initially, less fresh air is needed, however, during pinhead formation and cropping more-fresh air is required in the mushroom house since during vegetative growth mushroom requires high CO2 and during fruiting very less CO2 concentration (less than 0.3%).
Mushroom is to be picked at button stage, and for this, it is to be held between the thumb and first two fingers and rotated gently clockwise and anticlockwise and pulled out with bit care. Lower portion of the stem, which is covered with casing mixture, is trimmed with a sharp knife followed by washing and drying. For marketing, generally, the packaging is done in 100 gauge polyethylene bags containing 200 g mushrooms, and few holes are made in the packets to avoid condensation of the moisture in the bags.
Growers generally obtain an average yield of mushrooms 15-25 kg/100 kg compost within a period of 5-7 weeks, and the cost of seasonal cultivation comes is about Rs. 18-20/kg of mushroom, which fetches a price of Rs. 25-30/kg in the market.
3. How to Cultivate Oyster Mushroom?
In India, the cultivation of oyster mushroom was first described by Bano and Srivastava (1962) from Mysore. Pleurotus sajar-caju was first introduced into by Jandaik (1974). Pleurotus species has the ability to break down cellulose and lignin bearing materials without chemical or biological preparation. The straw is soaked overnight in water to achieve the moisture content of 70%, which also helps in the removal of some surface contaminants on the straw.
The simple containers like polyethylene bags, polyethylene tubes, gunny bags, bamboo baskets, wooden boxes, wooden trays, plastic sacs, plastic boxes etc. can be used for its cultivation. In all these cases, however, care should be taken for the exchange of gases by inserting some perforated tubes in the substrate heap to avoid anaerobic fermentation. Sterilization of the substrate is done by any of the four following methods, i.e., chemical sterilization, steam sterilization, hot water sterilization, and solar sterilization.
Spawning is the process of mixing the spawn in the substrate, and this could be regarded as analogous to seed sowing. Spawning is done @ 3-4% of the substrate.
The following methods are employed for spawning:
i. Surface spawning- Spawn can be broadcast evenly on the surface of the substrate.
ii. Double layer spawning- The substrate is spawned first at 5 cm layer than at the surface.
iii. Thorough spawning- Spawn is mixed thoroughly with the substrate.
It prefers a little high CO2 during spawn run, and after spawning, a relative humidity of 80-90% is maintained. A good harvest could be expected during rainy season. The temperature should be around 15-30°C depending on the species used for cultivation.
The mycelial impregnation in the substrate, which becomes white in colour due to growth of the fungus, is generally completed 15-20 days after spawning. Light is the initiating factor in the development of primordia, and is needed for at least 15 minutes per day. The mushroom should be harvested when the pileus is about 5-10 cm depending on the species before the spores are released.
The commonly cultivated species are Pleurotus florida, P. flabellatus, P. sajor-caju, P. cornucopiae, P. ostreatus, P. ostreatus (grey) and P. eryngii.
4. How to Cultivate Milky Mushroom (Calocybe Indica)?
The milky mushroom was first reported from India in 1974 and was first cultivated by Purkayastha and Chandra (1976). This mushroom is known by diverse names in different parts of the country, and the most common name is dudh chhata/safed dudhiya mushroom.
Its robust size, milky white colour, flavour, and long shelf life have attracted attention of both consumers and prospective growers. Subsequently, its nutritional requirements and nutritive value, which are at par with other edible mushroom, were also determined.
The cultivation method is similar as that of oyster mushroom, except that it requires casing. After 10-12 days of casing, the fruit primordia are formed and within 5-6 days the mature fruit bodies, which are ready for harvest, are seen. It requires high temperature, high relative humidity, diffused sunlight, and good aeration. Fruiting is affected in the absence of these conditions. For fruiting, the temperature range of 25-35°C is required. The pH of casing material should be around 7.0 and relative humidity more than 90%.
Diseases, Competitors, and Physiological Disorders of Button Mushroom:
The most common diseases/competitors and physiological disorders of mushroom, their cause, symptoms, and control management are given below in Table 27.4.
In mushroom beds, several trophic groups of nematode may occur but only fungal feeders (myceliophagous) are of major concern in crop production. These fugal feeders can easily be differentiated microscopically from other nematodes in possessing a needle-like stylet in their mouth, which they use in piercing the fungal cells. In India, nematode damage on mushroom was first revealed by Bhardwaj et al. (1972) from mushroom farms of Himachal Pradesh.
Several species of Aphelenchoides like A. composticola, A. neocomposticola, A. bicaudatus, Ditylenchus myceliophagus, Aphelenchus avenae and A. radicicolus are the most common in the mushroom beds.
Once introduced in the mushroom beds, the nematodes attack and suck the mycelial contents. Short life cycle of 8-10 days, high fecundity results in their rapid spread in the beds. They feed and kill a large number of fungal cells, ultimately causing complete mycelia destruction leading to non-production of sporophores.
Chemical nematicides cannot be used for controlling the nematodes mainly due to residual problems as the crop is of short duration, and mushroom is consumed fresh. Preliminary studies revealed that the water extract of neem-seed kernel 2% and achook 800 ppm, a neem-based pesticide, if applied at the time of spawning help in reducing the nematode damage.
In long method of composting, the nematicides like furadan 3G may be added at the time of first turning. The casing mixture should be properly sterilized and the racks/beds should be 25-30 cm above the ground. The compost should be prepared on a pucca floor.
Mushrooms are attacked by a host of insect-pests right from spawning to harvest. Of these, sciarid and phorid flies, springtails, and mites are important arthropods pests of cultivated mushroom in India. However, sciarid, Bradysia tritici, and phorid, Megaselia sandhui flies are quite common. Production of mushroom during summer is limited due to high infestation by mushroom flies.
The incidence of sciarid fly begins in the first week of February reaching peak in the second week of March, whereas, that of phorid fly, the incidence is initiated in the first week of March and reach its peak (approximately 90%) in the last week of March during seasonal low-cost cultivation.
There is significant positive relation between the flies’ incidence and the gain in temperature (around 20°C and above). With the increasing hazards due to excessive use of synthetic insecticides and increased awareness among the consumers about the side effects of these chemicals, however, there is good scope to explore the use of physical methods, biocontrol agents, and biopesticides.
Physical Methods:
Among physical methods, the use of greasy yellow colored light traps to trap the adult flies is the most important one.
Biological Control:
Steinernema feltiae nematodes may be applied before casing. Under laboratory conditions, phorids could be successfully infected by Heterorhabditis heliothis and S. feltiae nematodes. Some predators like midges, beetles, and bugs have been seen predating on mushroom flies.
Mites like Parasitus finetorum and Macrocheles merdarius have been observed parasitizing phorids. Phorids have also been seen predated by juvenile spiders in the mushroom laboratory. The wasps such as Crossocerus elongates and C. nigritus, have been found preying on some phorids and Apus apus (swifts) also predates on phorid flies.
Management by Chemicals:
Among these methods, the use of many synthetic chemicals like Lindane, Acephate, Chlorphyriphos, Deltamethrin, Diazinon, dimethoate, Etoprop, Fenitrothion, Methepreme, Diflubenzuron, Dichlorvos, and Malathion as prophylactic treatment, spraying on the compost, walls of the mushroom house and space and their incorporation in the compost have been found effective in controlling the flies.
Preservation and Processing Technology of Mushrooms:
Due to short shelf life, the produce remains acceptable for several hours only at high ambient temperature of the tropics and subtropics, thus, a knowledge of post-harvest handling practices plays a significant role in enhancing the availability of quality mushrooms either in fresh or processed form to the consumers and at the same time ensuring remunerative prices to the producers.
Causes and Consequences of Mushroom Deterioration:
Absence of protective covering on the surface, imbalance in metabolism and lack of inherent antimicrobial mechanism on harvest make the mushroom prone to attack by associated microflora, which leads to discolorations, patches and slimy growth.
In peak season, adopting appropriate post-harvest technologies can make glut of mushrooms in the market. Development of appropriate storage and processing technology in order to extend their marketability and availability to the consumer in fresh as well as processed form is of great significance.
The post-harvest technology of mushroom includes:
Harvesting of mushrooms at optimum stage of maturity is of great importance since harvesting of under mature or over mature fruit bodies results in poor texture, flavor and immediate degradation.
Sorting is done to remove the undesirable fruit bodies from the produce. In sorting, the attributes taken into consideration are discoloration, blemishes and shape. It helps in getting premium price to the producer and delays the deteriorate processes.
Though mushrooms are grown in shades, these require to be pre-cooled immediately after harvest to their optimum storage temperature (5°C) to arrest the high respirative and deteriorative changes, which are otherwise very fast at ambient room temperature.
To maintain whiteness, the mushrooms are dipped in dilute solution of hydrogen peroxide (1:3) for half an hour, and then, steeping in 0.25% citric acid solution containing sulfur dioxide 500 ppm has significant effect. It is a common practice to wash the produce in 0.025 to 0.05% potassium metabisulphite solutions to maintain the whiteness of the produce and to remove any adhering casing soil, compost or other substrates.
Since mushrooms are very sensitive to desiccation and draught, selection of suitable package is very important. Mushrooms are usually packed in polypropylene bags of 200-500 g capacities. In 100 guage polyethylene bags 0.5% ventilation is generally recommended for refrigerated storage, whereas, non-perforated bags can be used for local markets.
Mushrooms being highly perishable and having a high rate of respiration, is transported in refrigerated vehicles for distant markets, however, for local markets, the precooled mushrooms picked in suitable packages should be transported in insulated ice containers.
During storage, metabolic activities of tissues continue where consumption of oxygen and production of carbon dioxide continue along with loss of moisture, which is dependent upon relative humidity of the surroundings. In an open atmosphere, the relative concentrations of oxygen, carbon dioxide, and water vapors remain steady, and the deterioration is affected through loss of moisture, weight, and surface growth of contaminants.
In case of closed system, the oxygen depletion and carbon dioxide accumulation lead to anaerobiosis and shift in metabolism from respiratory to fermentative and putrefactive activity which in turn results in the development of off-flavor. Transpirational flow of water vapours leads to the condensation and dew formation on container internal surface.
To avoid undesirable changes scientific considerations lead to two types of storage packaging systems based upon atmospheric controls, i.e., Controlled Atmosphere Storage (CAS) and Modified Atmosphere Packaging (MAP).
In the CAS, a low temperature with more than 2% oxygen and less than adding or deleting these constituents in storage maintains 10% carbon dioxide cabins. In case of MAP, the packaging materials and their thickness are suitably selected for modifying the atmosphere through differential transfer rates of gaseous constituents.
A temperature of 5°C along with 85-90% relative humidity is generally recommended for the storage of mushrooms. At ambient temperatures, the steeped mushrooms can be kept for 8-10 days.
Preservation and Processing of Mushrooms:
In view of the highly perishable nature, the fresh mushrooms have to be preserved to extend their shelf life to off-season use.
The technologies for the processing of mushroom are as under:
1. Preservation by Low Temperature:
Individual quick freezing (IQF) technology is employed to yield a product of excellent quality with longer shelf life. Quick freezing is a process where temperature of the mushrooms passes through the zone of maximum crystal (0-3°C) in 30 min or less. Freezing stops microbial activity. Enzymes activity is only retarded at freezing temperature. However, the mushrooms prior to freezing require blanching to control the enzymes activity, and the storage temperature is maintained at – 35° to – 40°C to obtain the best performance.
The main objective of drying is the removal of free water to such a level that the biochemical and microbial activities are checked due to reduce water activity in the product. Blanching and sulfuring/sulfiting are important treatments given before drying. Pre-drying soaking of blanched slices in potassium metabisulphite (1%) + citric acid (0.2%) + sugar (6%) + salt (3.0%) solutions for 16 h followed by drying at 60 ±2°C for 5-8 h yields best product with longer shelf life.
Sealing the mushroom cans hermetically to prevent the recontamination and the use of high temperature to destroy the microorganisms is the main principle of preservation. Generally, the small size buttons without stem attached are required for canning purpose. Ascorbic acid, ethylene diamine tetra-acetic acid (EDTA) and citric acid have been recommended as useful adjunct for improvement of colour in canning of mushrooms.
This is the most effective method of preservation since application of gamma radiation not only retards the deteriorative processes but also increases the shelf life of mushroom retaining the same quality up to 10-14 days if preserved at 5°C temperature.
Several chemical additives, which are non-nutritive, are added in small quantities in foods to improve its appearance, flavour, texture, and storage properties. These additives contribute substantially in the preservation. The mainly used additives are salt, sugar, acetic acid, vinegar, spices, oils etc. On the other hand, the chemical preservatives maintain nutritional quality and enhance the keeping quality. Potassium metabisulphite is commonly used as preservative in the processing of mushrooms.
6. Preservation by Lactic Acid Fermentation:
Fermentation is a process of anaerobic or partial anaerobic oxidation of carbohydrates. During the process of fermentation, sufficient quantity of lactic acid is produced to prevent the product from further spoilage during storage.
During the three months of its growth, Agaricus mushroom continues the process of breaking down and utilizing the organic material of its substrate to form fruiting bodies. After this, the substrate is removed from the growing chamber. For the past, this product known as spent mushroom substrate (SMS) was regarded as useless waste product.
Among the uses, the developed to date uses are:
i. Used for the purification of contaminated air, soil, and water. SMS has chemical ability to absorb organic and inorganic pollutants in addition to microbial population that can break down a number of them.
ii. Remediation of soil, adding SMS to poor soil and/or soil lacking in organic matter considerably improves its fertility.
iii. In horticulture, after providing suitable treatment, the SMS can be used as a partial substitute of peat in artificial/detached medium for growing flowers, vegetables, and saplings.
iv. As an organic fertilizer, the chemical analysis has shown that SMS is rich in nitrogen, phosphorus, and potassium, which are released slowly and steadily, therefore, SMS can be composted for use in organic farming, in which no chemical fertilizer and other synthetic materials are used.
v. Another area involving the utilization of SMS is as animal feed. It can also be used as biogas production.