Mushrooms: Meaning, Values and Cultivation Procedure

In this article we will discuss about:- 1. Meaning of Mushrooms 2. Values of Mushrooms 3. Cultivation Procedure.

Meaning of Mushrooms:

Mushrooms are the fruit bodies of edible fungi, commonly belonging to Basidiomycotina (Agaricus campestris, A. brunnescens, Pleurotus sajor-caju, Volvariella volvacea etc.) and rarely to Ascomycotina (Morchella conica, M. esculenta).

The mushrooms were used as food since long back, probably from 3000 B.C. as per ancient Indian literature. Since that time, the mushrooms are being consumed in different countries like Greece, Egypt, France etc. The Greeks and Romans described mushrooms as “food for the god”. During that period, people consumed the mush­rooms after collecting them from their natural habitat.

The cultivation was started in the early part of 18th century in France, but it became a thriving industry only by 1850 in Paris. In India, the first successful experimental cultivation of mushroom (A. bisporus) was initiated at Solan (Himachal Pradesh) in 1961. Later on, the cultiva­tion of mushrooms gradually becomes popular with edible mushrooms in different parts of our country.

Assessment of nutritional value of mush­rooms has been demonstrated that they comple­ment and supplement the human diet and these are considered as “delight of the diabetic”. Mushrooms have rightly been referred to as the “ultimate health food”.

But there is no definite test to confirm whether a mushroom is poisonous or edible. Alexopoulos, Mims and Blackwell (1996) expressed the warning in their book “Introductory Mycology” to the Mushroom-consumers that “you can commit many mistakes in your life, but of consuming a poisonous mushroom only once”.

Value of Mushrooms:

1. Nutritive Value:

Mushrooms became popular for their food value. The food values of mushrooms are as follows:

i. Mushrooms are the richest source of vege­table protein.

ii. The protein content varies from 1.1-4.98% in common cultivable mushroom (much higher than pulses, vegetables and fruits).

iii. All the essential amino acids including lysine (550 mg/gm) are present in much higher amount than even egg.

iv. Mushrooms contain sufficient quantities of mineral elements such as Na, K, Ca, P and Fe.

v. Mushrooms contain folic acid.

vi. Mushrooms contain vitamins like B, C, D and K.

vii. They contain little amount of fat (0.35- 0.65% dry wt.) and starch (0.02% dry wt.).

Different chemical contents of mushrooms and other foods are given in Table 4.15-4.18:

2. Medicinal Value:

Most of the mushrooms have high medicinal value to reduce blood pressure, obesity (to be fatty), constipation, atherosclerosis (fat deposi­tion inside blood vessel) etc. Medicinal value of some mushrooms are given in Table 4.19.

3. Biological Value:

Biologically mushrooms are very much important. The biological value includes nutri­tive value, medicinal value and their efficiency in degradation of substrate.

Cultivation Procedure of Mushrooms:

It is the technique to develop the fruit bodies of edible fungi. About a dozen fungi are culti­vated in 100 countries with an annual produc­tion of 2.2 million tonnes. The common four genera are Agaricus, Lentinus, Volvariella and Pleurotus.

Together, they yield a major share of the total production. Out of many, Agaricus brunnescens (syn. A. bisporus), white button yields 56%; Lentinus edodes, shiitake yields 14%; Volvariella volvacea, paddy straw yields 8% and Pleurotus spp., oyster 7.7%.

The culti­vation procedure of some of the mushrooms is given:

A. Cultivation of Agaricus Brunnescens (Syn. A. Bisporus):

The Agaricus brunnescens (syn. A. bisporus) is commonly known as white button mushroom (Fig. 4.107, 4.108). It contributes a major share in the mushroom production of the world. It is a temperate mushroom and can grow well in temperate conditions. Optimum temperature, optimum moisture, proper ventilation and good quality of spawn are very essential prerequisites for mushroom growth.

These are:

a. The optimum temperature for the mycelial growth is 24°C, while it is 14-18°C for the formation and develop­ment of fruit body.

b. Optimum moisture requires nearly at the saturation point. However, direct application of excess water in bed is harmful for the growing crop.

c. Proper ventilation is essential to remove toxic gases by the introduction of ade­quate fresh air.

d. Good quality of spawn i.e., the spawn should be prepared from the tissue of single fruit body and its productive capacity should be good enough.

The cultivation procedure is:

1. Production of spawn,

2. Preparation of compost,

3. Filling of trays with compost,

4. Spawning i.e., inoculation of compost,

5. Watering of inoculated compost filled trays,

6. Casing,

7. Harvesting of mushrooms (fruit bodies), and

8. Storage of mushrooms.

1. Production of Spawn:

The spawn (seed of mushroom) is a pure cul­ture of the mycelia grown on a special medium. The medium is prepared by the grains of wheat, rye, sorghum or bajra along with some ingredi­ents.

The preparation of spawn mainly consists of three steps:

a. Preparation of substrate,

b. Inoculation of substrate, and

c. Incubation of inoculated substrate for spawn production.

Preparation of Substrate:

Take 900 gms of grains (wheat or sorghum) in 600-900 ml of water in a container and boil for 15-20 minutes, After boiling, decant the excess water and allow the grains to surface dry­ing by spreading on polythene sheet in shade for a few hours.

The grains are then mixed with chemicals like 2% calcium sulphate (gypsum) and 0.5% calcium carbonate (chalk) on dry weight basis and adjust the pH of the grain at 7-7.8. About 300-350 gms grains were then filled in milk bottles/ polypropylene bags.

Place a ring of tin (3.5 cm height and 3 cm diametre) towards the inner side of the open-end of polypropylene bag, tighten it with rubber band and then push the margin of the bag towards the inner side and thus a mouth is prepared.

Plug the mouth of the bottle and/or polypropylene bag with non-absorbent cotton. Then cover the mouth with brown paper and tighten it with rubber band. Sterilise the substrate by autoclave at 15lb pressure for 30 minutes for 2 consecutive days. Kept the sterilised substrate in open air to cool down near to room temperature, thus making the substrate ready for inoculation.

Inoculation of Substrate:

The substrate is then inoculated with the mycelial culture (developed earlier, either in Potato Dextrose Agar i.e., PDA or Yeast Potato Dextrose Agar i.e., YPDA or Malt extract Agar and Rice bran decoction medium).

Incubation:

Incubate the inoculated container at 20-25°C in dark for 3 weeks. Shake the contai­ner after a few days, when the mycelial growth becomes visible on the grain.

Storage of Spawn:

Store the spawn at 0-4°C in a refrigerator for a maximum period of 6 months, if it is not nee­ded immediately.

The spawn can be purchased from any spawn-growing centre. (The spawn is also avai­lable in “National Centre for Mushroom Research and Training (NCMRT)”, Chambaghat, Solan 173 213, Himachal Pradesh, India.

2. Preparation of Compost:

The compost used in the cultivation are of two types:

Natural and Synthetic:

i. Natural Compost:

The natural compost is prepared by mixing barley or wheat straw with fresh and pure horse dung (not with the dung of other animal). Mixed, rain wet or old dung is not sui­table for the preparation of compost. Commonly 100 kg of dung is mixed with 33 kg of straw. The mixture is then stacked a metre high heap.

The heap of mixture should be kept under shade in open air. After 3-4 days, the heap was turned (to release ammonia) and stacked again. The turning process is repeated 4-5 times at an interval of 5-6 days. During this process, gypsum (CaSO₄.2H₂O) is added @ 25 kg/tonne (1,000 kg) dung. Finally, 40 ml nemagon is sprayed and added to the mixture. The compost was then filled in the tray of 100 x 50 x 15 cm size.

ii. Synthetic Compost:

The ingredients required for the synthetic compost are:

(a) Chopped wheat straw (3-6 cm size) 300 kg

(b) Wheat bran 30 kg

(c) Calcium ammonium nitrate or Ammonium sulphate 6 kg

(d) Urea 4 kg

(e) Potash 1.5 kg

(f) Calcium sulphate (gypsum) 30 kg

(g) Sawdust 10 kg

Wet the sawdust with water by spraying and mix half of the ingredient, except wheat straw and gypsum. Next day, spread the wheat straw on the cement floor and wet it thoroughly by spraying with water. The sawdust-chemical mix­ture is then mixed thoroughly with wetted wheat straw. This mixture is then stacked under shade into a metre high heap and covered with poly­thene sheet.

After 5 days, the stack is scraped and rest half ingredient is thoroughly mixed with it and the entire mixture is then stacked again. This process is repeated six times. Calcium sulphate is added in the 3rd and 4th turning.

Normally the compost becomes ready to cultivate after 6th turning, but 2 or more turning may be given if the smell of ammonia is yet there in the compost. During last turning, insecticide like malathion (10 ml dissolve in 5 I water) is added to the pre­pared compost. The prepared compost will be brown or dark brown in colour and is sufficient enough to fill 25 trays of 100 x 50 x 15 cm size.

3. Filling of Trays with Compost:

Mix 3 kg of calcium carbonate with the compost prepared earlier. Fill the wooden trays with compost and compress fairly by using a wooden board (1 2 cm x 25 cm), so that a space of about 3 cm deep is left on the top of the tray.

4. Spawning i.e., Inoculation of Compost:

Spread the spawn on the surface of compost and then cover by a thin layer of compost. Little pressure with the fingers is given to make good contact of spawn with compost. Finally the trays are covered with old newspaper. The trays are arranged one after the other in vertical stacks in such a way that sufficient aeration between the trays is maintained.

5. Watering of Inoculated Compost Filled Trays:

Sprinkled water to be given on newspaper to maintain humidity. Water should be applied twice a day or less depending on the availability of moisture. The room temperature should be maintained between 24°C and 25°C for 12-15 days for the good growth of mycelium on the compost. The mycelium appears in the form of white cottony growth on the surface of bed.

6. Casing:

The process of covering the mycelial mat on compost, surface is made with a thin layer of soil mixed with different substances.

The casing can be done with different types of mixture like:

i. Soil : Sand : : 1 : 1;

ii. Well-rotten cow dung: light soil: : 3 : 1 ;

iii. Spent compost: Sand: Slaked lime : : 4:1:1 etc.

Casing soil should be sterilised either by chemicals like methyl bromide, formalin etc. or by heating at 70-75°C temperature for 6 hours to kill the inhabiting fungi, nematodes, insects etc.

The fruit bodies of mushroom are expected to appear after 5-20 days of casing. After casing, the room temperature should be maintained between 14-18°C for the good growth of the fruit body. The fruit bodies attain the size of button stage from pinhead within 7-8 days. Next crop appears at an interval of 8-10 days.

7. Harvesting of Mushrooms i.e., Fruit Bodies:

When the cap of the fruit body is tight with its stalk, the fruit bodies are harvested. The fruit bodies are harvested by twisting and uprooting, after holding the basal region of stalk with fin­gers. The lower part of the stalk is cut out where the compost remains attached.

8. Storage of Mushrooms:

The fruit bodies may be stored at 4°C for a few days, if it is not consumed or marketed immediately.

B. Cultivation of Paddy Straw Mushroom (Volvariella Volvacea):

The paddy straw mushroom is also called tropical, straw or Chinese mushroom (Fig. 4.109). In West Bengal, it is called as ‘Poal chatu’. The genus Volvariella belongs to the family Pluteaceae under the order Agaricales of Basidiomycotina.

The common edible species under this genus are V. volvacea, V. diplasia and K esculenta; those are grown commercially in different countries like Burma (Myanmar), China, Philippines, Malaya, India etc.

In addition to paddy straw, other substrates like water hyacinth, cotton waste, banana leaves, sawdust, sugarcane thrash (bagasse) etc., are used as substrate due to the presence cellulose, hemicellulose and lignin.

In India, the cultivation of this mushroom was first initiated in Coimbatore, Tamil Nadu, and now it is popular in different tropical parts due to the requirement of temperature ranges between 30-45°C.

The process of cultivation of straw mush­room is as follows:

1. Requirements,

2. Preparation of spawn,

3. Cultivation procedure,

4. Harvesting of fruit bodies, and

5. Preservation of fruit bodies.

1. Requirements:

i. Spawn of V. volvacea (600-800 gms grain spawn/bed),

ii. Bricks,

iii. Bamboo frame (1 m x 1 m),

iv. Small water tank,

v. Paddy straw (preferably from aman variety), apx. 36 kg,

vi. Loose straw 5-6 kg,

vii. Powder of Gram or Arhar seeds 200-250 gm,

viii. Thermometer (0-100°C scale), and ix. White polythene sheet.

2. Preparation of Spawn:

The spawn can be prepared following the same procedure as adopted in Agaricus brun­nescens (see page 395). But in addition to grains of wheat or sorghum, the rice straw can also be used as substrate.

3. Cultivation Procedure:

Fresh paddy straw, not more than one year old and preferably from the Aman variety, should be collected from farmer or from any store. 24 straw bundles of about 1.5 kg each along with some loose straw are immersed completely in a water-filled tank by putting some weight on the bundles for about 12-15 hours.

Then take out the straw bundles from the tank and keep them in stack on cement floor to drain off excess water.

4. Preparation of Bed and Spawning:

One square bed of 1 m x 1 m x 1 m or 1 m x 0.75 m x 1 m is prepared with pre-soaked straw, keeping the butt ends (basal region) at one side, placed close to each other and arranged length-wise on a bamboo frame, supported on 4 pillars made of bricks. Same number of soaked straw bundles are placed on the previous one by keeping the butt ends in opposite direction.

Inoculate the bed with spawn. The bids of spawn are placed about 8-10 cm inside the margin, maintaining a space of about 5 cm from each other. About 160-200 grams spawn is required for each layer. Powders of Cram or Arhar seeds of about 50 gms or more are spread along the line of spawning.

Second and third layers are arranged and inoculated in a similar process, but 2nd layer is placed at right angle to the 1st layer and the third layer is like the 1st layer. The spawn and seed powder on the 2nd layer will be given like the 1st layer, but on the 3rd layer those will be dis­tributed uniformly throughout the bed.

Finally, cover the top layer with loose straw. Loosely bind the bed with rope made of wheat straw at the three regions, one in the middle and one on each side. Press the bed with the help of woo­den board to release the internal air and thus the spawn get compressed with the wet straw bun­dles. Cover the bed with polythene sheet.

Watering should be done once or twice with the help of micro-sprayer. The temperature of the bed should remain 30-35°C after spawning and it should not go below 30°C during the growing season. The relative humidity should be between 80-90%.

Polythene sheet should be removed after 7-10 days of spawning for the appearance of button of the mushroom. After that the buttons quickly develop into fruit bodies.

The straw once used in the mushroom culti­vation can be used again. The bed should be pre­pared under shade away from direct sunlight and rain and also in well-aerated condition, but wind should not blow very fast.

5. Harvesting of Mushroom:

The fruit bodies are harvested by gentle twisting when the volva is about to rupture or is just ruptured. The production continues for 25- 30 days, but in two phases. The total production per bed is approximately 3 kg. The production of second phase is comparatively less.

6. Preservation:

The fruit bodies are consumed fresh or can be preserved by drying or in refrigerator for 27- 48 hours. Drying can be done either in the sun or in oven at 50-60°C temperature.

C. Cultivation of Oyster Mushroom (Pleurotus):

Species of Pleurotus are commonly called Oyster mushroom or Dhingri or Wood fungus (Fig. 4.110). It is the fourth important mushroom in the world ranking with an annual production of about 15,000 tones. It grows commercially in Japan, Taiwan, Italy, France, Thailand, Philippines and India, out of which the first three are the leading countries in its production.

The genus Pleurotus contains more than 50 species, of which P. flabellatus, P. ostreatus, P. sajor-caju, P. sapidus, P. fossulatus, P. cornu- copieae, P. sapathulatus and P. florida have been cultivated in India.

The process of cultivation of Oyster mush­room is as follows:

1. Requirements,

2. Preparation of spawn,

3. Cultivation procedure,

4. Harvesting of fruit bodies,

5. Preservation of fruit bodies.

Requirements:

i. Spawn of Pleurotus – 60 gms (30 gms grain spawn/kg of paddy straw),

ii. Chopped and dry paddy straw (1-2 cm) -2 kg,

iii. Gunny or polythene bag (40″ x 24″) – 1 piece.

iv. Horse gram powder – 50 gms (25 gm.s/kg),

v. Thick polythene sheet (5 ft x 5 ft) – 1 piece,

vi. Polythene bags (30″ x 18″) – 2 piece, and

vii. Water sprayer. Preparation of spawn

The spawn can be prepared as per method adopted in Agaricus brunnescens (see page 395). The spawn should not be older than 1 month.

Cultivation Procedure:

Take two kg of chopped straw (preferably of Aman variety) in a gunny or incised polythene bag and tighten the mouth with rope. Immerse the bag completely in water (90 I water contai­ning 7 gm Bavistin, a fungicide along with 125 ml formaldehyde) filled tank by putting some weight on it for approximately 12-15 hours.

Then take out the straw bags from the tank and keep the straw pieces in a wicker basket or a scuttle (Beng. Jhuri). Put more water in the wet straw to remove dirt, rags etc. Wait for one or more hours to drain off excess water.

The wet straw pieces are then kept on polythene sheet and mixed with powder of Horse gram (20-25 gms/kg) and spawn (30 gms/kg) and if possible 10 gms ferti­liser of IFCO or P.P.L (10:26: 26) may be added.

Take 2 polythene bags (appx. 30″ x 18″) and make 6-12 holes at the lower side of each bag. Then the entire mixture is put equally inside the two bags. Keep the filled bags on a bench or table in a room at 21-30°C and 65-80% humidi­ty, with sufficient light and ventilation for 15-16 days, for spawn running.

Spray water on bed twice a day by micro-sprayer. After 15-16 days, the straw pieces are covered with the mycelium and form a solid cylindrical mass. Remove the polythene bag and keep the mass on the same polythene bag in the same place. The compact mass should be watered 4-8 times throughout the day with the micro-sprayer.

The young fruit bodies will be developed after 3-4 days (i.e., 18-20 days of spawning) from all sides of the bed.

Within 2-3 days, the fruit bodies attain the size of harvesting. After harvesting the straw- mycelium mass again put inside the bag and tighten the-mouth with rope. Keep it for 7 days and then again remove the mass from polythene bag and keep the polythene bag as before.

Next crop of mushroom will be available within 7 days i.e., approximately 36 days after starting. Repeat the process again and the third crop will be available in 50 days. During cropping period light should be provided for 15-20 minutes/day for better yield.

Harvesting of Mushroom:

The fruit bodies are harvested by gentle twisting after holding the base of the fruit bodies with fingers. The fruit bodies can be harvested generally 3 times i.e., at 22, 36 and 50 days and the total production will be 2 kg. Afterwards the bed should be destroyed.

Preservation:

After harvesting, the fresh mushrooms can be sold in the market or they can be dried in sun (for three consecutive days) or in oven at 65°C. The cultivation of Pleurotus can also be done on earthen tray or tub.

Other Modified Procedure:

Like the above procedure, the mixture is prepared and the tray or tub is filled with the mixture. The open end should be covered with polythene sheet. Watering should be done twice a day (varies with requirement) with the micro- sprayer.

The mycelium will spread throughout the sub-stratum within 10-12 days. The fruit bodies will start to develop after 20-24 clays of spawning. Within 2-3 days the fruit bodies will be the size of harvesting.

Some Edible and Poisonous Mushrooms:

Both edible and poisonous mushrooms are available in nature. List of some edible and poisonous mushrooms are given below. Common name of mushrooms are given in parenthesis.

A. Edible Mushrooms:

a. Members of Basidiomycotina:

1. Agaricus brunnescens (white but­ton),

2. A. campestris (field mushroom),

3. Pleurotus edodes (shiitake),

4. P. sajor-caju (oyster),

5. Volvariella volvacea (paddy straw) etc.

b. Members of Ascomycotina:

1. Morchella conica,

2. M. esculenta.

B. Poisonous Mushrooms:

1. Amanita phalloides (death cap): Toxic principles are α and β-amanitin, and phalloidin.

2. A. virosa (destroying angles),

3. A. verna (fool’s cap),

4. A. muscaria (fly-agaric) etc.

Diseases of Mushrooms:

Like higher plants, mushrooms also suffer from different diseases caused by fungi, bacteria and viruses.

List of some diseases are given in Table 4.20:

Other Organisms which Hamper Mushroom Yield:

In addition to diseases, mushroom yield is also hampered by molds and animal pests.

Molds:

Different types of molds are asso­ciated with mushroom growing. Molds are considered as competitors for nutrients or anta­gonists rather than parasites.

Name of different molds associated with mushroom cultivation is given:

1. Olive-green mold (Chaetomium olivaceum),

2. Green mold (Trichoderma viride),

3. Fire mold (Neurospora crassa),

4. Red geotrichum or lipstick mold (Sporen-donema purpurescens),

5. Sepedonium yellow mold (Sepedonium spp.),

6. White plaster mold (Scopulariopsis fimicola),

7. Brown plaster mold (Papulospora byssina),

8. Black whisker mold (Doratomyces stemonites),

9. Inky cap (Coprinus lagopus and other spp.),

10. Cinnamon mold (Peziza ostracoderma, syn. Plicaria fulva) etc.

Animal Pests:

Like molds, different animal pests also hamper the yield and quality of mush­rooms.

These are:

Major Pests:

1. Mushroom flies: Sciarids, Lycoriella solani, L. auripila,

2. Phorids: Megaselia halterata,

3. Phorids: M. nigra,

4. Cecids: Heteropeza pygmaea, Mycophila speyeri and M. barnesi,

5. Tarsonemid mite: Tarsonemus myceliophagus,

6. Red peppes: Pygmephorus spp.

7. Predatory mites: Parasitus fimetorum, Digamasellus fallax, Arctoseius cetratus,

8. Mycophagous eelworms: Ditylenchus myceliophagus and Aphelenchoides composticola.

Minor Pests:

Collembola: Archorutes armatus

Sphaeroceridae: Leptocera heteroneura

Drosophilidae: Drosophila tunebns etc.