In this article we will discuss about mushroom and its cultivation in India.
Meaning of Mushrooms:
Mushrooms are the fruiting bodies of basidiomycetous fungi and are specifically called basidiomata (sing, basioma). They are formed only during certain periods of the year when conditions are congenial, and are bright coloured. Mushrooms may be edible or non-edible, poisonous or non-poisonous.
The poisonous mushrooms are popularly known as ‘toadstools’. The simple mushroom has the fruiting body looking like umbrella. The fruiting body contains spores which are invisible to the naked eye. These spores fall on the substratum, germinate under suitable conditions, and send out exploratory root-like mycetial strands in all directions. Gradually the fruiting body of mushroom appears as a tiny, white ball.
As it grows further, a stem (stipe) is produced, and later the cap (pileus) begins to open up like an umbrella tearing away the delicate membrane or veil (or velum).
Inside the cap, delicate gills (or lamellae) are developed which somewhat resemble the spokes of a wheel radiating from the stalk. The gills become dark coloured as spores appear on them. When they attain maturity, the cap of the mushroom begins to flatten out. The spores are eventually released to the ground in millions.
Though millions of spores are produced and distributed, majority of them do not survive due to non-availability of favourable conditions and other factors. Even when spores happen to germinate, their mycelium is very sensitive and is liable to be attacked by other fungi, bacteria, viruses and nematodes. In fact, even when growth is firmly established there are seasons when only a few mushrooms survive in the field.
Why Mushrooms be Eaten ?
Why mushrooms has become popular as food ? Is it due to changing food habits of modern people under present circumstances, or have people developed some special attraction for them? Mushrooms are becoming popular not only for their flavour and taste but also for their nutritive value.
Like many other vegetables, mushrooms contain a high proportion of water apart from other constituents. They usually contain more protein (about 51%) than many other comparable fruits or vegetables (on a dry weight basis) and as such can claim to be a “protective food”.
It is known that mushrooms are one of the best plant sources of nicotinic acid and riboflavin (vit. B12), a good source of pantothenic acid, and a fair source of vitamins B,C,K, biotin and thiamine. It appears from the literature that its vitamins are well retained during the process of cooking, canning, drying and freezing.
In some cases linoleic acid has been found to be the main fatty acid component. Carbohydrate contents, however, vary between 28 to 76%. Moreover, mushrooms being completely devoid of starch, constitute an ideal dish for diabetic patients.
They also contain an appropriate amount of minerals, lipids and folic acid. Like many vegetables they can be stewed or backed, fried or sandwiched, can be used in soup or ‘puree’, in sauce, and also in toast tomatoes stuffed with mushrooms.
Commercial Production of Mushroom:
At present, mushroom-cultivation is being run commercially in many countries and the world production of mushrooms is estimated to be more than 300,000 metric tonnes. As stated earlier, only a relatively few species are commercially cultivated in comparison to- the number of mushrooms known.
The most commonly cultivated mushrooms are: Volvariella volvacea (the Paddy-straw mushroom) in India, China and South East Asia; Agaricus brunnescens (A. bisporus; the Bottom mushroom), the commercial name of the wild species A. campestris because the latter when artificially cultivated shows remarkable alterations in its morphology and physiology; Lentinus edocles (Shii-take) in China and Japan.
The Paddy-straw mushroom (Volvariella volvacea) is cultivated on straw, the Shii-take mushroom (Lentinus edodes) on logs and the Button mushroom (Agaricus brunnescens) on composed horse manure.
In Europe and North America, the mushroom cultivation has become a large industry; in Great Britain and USA, large quantities of mushroom are available for canning and food manufacture as well as for direct consumption. Several million pounds of the Shii-take are produced annually in Japan and China.
Mushroom Cultivation in India:
In India, mushroom-cultivation is in progress. Impressive work is being done in States like Himachal Pradesh, Tamil Nadu and Uttar Pradesh. Our country is gifted with two distinct climates and seasons, namely, winter and summer. Accordingly, we can divide mushroom cultivation and can easily cultivate them under natural conditions almost round the year.
Volvariella spp. (Paddy Straw Mushroom) can be grown in summer when the temperature ranges from 28°C to 49°C; Pleurotus spp. (Dhingri) can be grown in winter when temperature is about 20° to 30°C; and Agaricus bisporus (Button Mushroom) can be grown in winter when temperature ranges from 15°C to 25°C.
1. Cultivation of Paddy Straw Mushroom (Volvariella spp.):
The steps involved in cultivation of paddy straw mushroom are : choice of substratum, bed-preparation and cropping, after care of beds, and harvesting and marketing.
Choice of Substratum:
Paddy straw is considered to be the best; others which can be used are wheat straw, jowar, maize, rye straw, sugarcane bygasse, tobacco and banana leaves.
Bed-preparation and Cropping:
Firstly, hand-harvested, 3-4′ long, well-dried and disease-free paddy straw are taken to prepare their bundles, 35 bundles of paddy straw are required for one bed and each such bundle should be 1 to 1.5 kg in weight. The bundles are soaked in water for 8-16 hours, are taken out of water, washed with fresh water and allowed to drain off excess water. (Fig. 37.2).
Now, a bed is prepared by putting four layers of the paddy straw bundles one over the other; each layer contains 8 bundles. The spawn bottle is opened and raked with a woolen or glass rod. The spawn is now sprinkled by hand all over on the margin of the bed about 10 cms. away from the edge and continuing upto 23 cms. inside. Thus the central portion has been left for spawning in 1st layer.
The sprinkled spawn is covered with a light dusting of ‘besan’ (gram powder). The second, third and fourth layers are also prepared in the same way as in case of 1st but the difference in 4th layer is that the sprinkling of spawn is done on the entire surface instead of periphery as in case of rests of the layers.
The layer should also be dusted by the gram powder and must be covered with a thin layer of straw upto 8 cms. thickness. This is also done with the remaining three bundles of straw.
After Care of Beds:
Water is sprayed 2-3 times in hot day and 1-2 times in rainy season. If necessary, 0.1% Malathion and 0.2% Dithane Z-78 is sprayed to overcome insects, pests and other diseases.
Harvesting and Marketing:
Cropping starts 10-12 days after spawning and remains upto 15-20 days. Mushroom is harvested at button stage or just after rupturing of the cup by twisting so that broken pieces are not left in the beds otherwise bacterial rotting generally starts and spreads to other healthy mushrooms.
After harvesting the mushrooms should be used within 8 hours or kept in 10-15°C for 24 hours otherwise these get spoiled. One may keep them for a week in refrigerator.
Fresh mushrooms are dried either in sun or in even at 55-60°C for 8 hours. After drying they are packed and sealed otherwise they absorb moisture which spoils them. The packing of mushrooms is preferred only in button state. However, one can find 3-4 kg. yield/bed of mushrooms.
2. Cultivation of Dhingri:
The steps involved in cultivation of dhingri (Pleurotus spp.; Fig. 37.3) are: choice of substratum, bed- preparation and cropping, after care of beds, and harvesting and marketing.
Choice of Substratum:
Chopped paddy straw is the best; others may be crushed maize cobs, wheat straw, rye straw, dried and pulvarized grasses, compost used in button mushroom cultivation, and wooden logs etc.
Bed-preparation and Cropping:
Chopped paddy straw is soaked in water tank for 8-12 hours, are taken out and washed again with fresh water, and allowed to drain off excess water. Now the substratum is filled in wooden trays measuring about 1 x 1/2 x 1/4 metre. The entire surface of the tray-filled substratum is sprinkled by spawn.
After spawing is over, the tray is covered by polythene sheet and spraying of water is done once or twice a day or if and when necessary to maintain the sufficient moisture in the tray.
However, the mushroom fruiting bodies, generally called mushroom-flush, start appearing after 10-15 days and the polythene sheet is removed when mushroom start appearing. Production of mushrooms continues upto 1-11/2 months (30-45 days) after appearance of 1st mushroom-flush.
After Care of Beds:
Water is sprayed as and when necessary; temperature and relative humidity is maintained at 25 ± 5°C and 85-90% respectively in the production room; aeration is provided; and 0.1% Malathion and 0.2% Dithane Z-78 are sprayed to control insects, pests and other diseases.
Harvesting and Marketing:
Mushroom is harvested when the pileus reaches about 8-10 cms. in diameter. The harvesting is done by twisting so that broken pieces are not left in the trays otherwise microbial rotting generally starts and spreads to other mushrooms.
Harvested mushrooms are dried in sun or in oven at 55-60°C for 8 hours. After drying, they are packed as otherwise they absorb moisture and get spoiled. However, one can find 3-4 kg yield/tray.
3. Cultivation of Button Mushroom:
The steps involved in cultivation of button mushroom (Agaricus bisporus; (Fig. 37.4) are: substratum and its preparation, bed-preparation and cropping, after care of beds and harvesting and marketing.
(i) Substratum and its Preparation:
The preferred substratum for button mushroom cultivation in our country is wheat or paddy straw compost.
Wheat straw 300 kgs., wheat bran 25 kgs., ammonium sulphate 9 kgs., super phosphate 3 kgs., urea 3 kgs., muriate of potash 3.5 gs., gypsum 30 kgs. saw-dust 30 kgs., zinc sulphate (ZnSO4) 10 gms., lindane or lintaff or gamma B.H.C. one kg. and Malathion 200 c.c.
The ground on which compost is prepared should be of cement concrete and clean, provided with a roof so as to get rid of rain and temperature due to sunlight. Now, firstly, the wheat straw is wetted for about 48 hours. Wheat bran, ammonium sulphate, super phosphate, urea and muriate of potash are mixed in saw dust.
This mixture (called fertillizer-heap) is watered adequately for about a day. Next day, the mixture is mixed to the watered wheat straw, and is stacked into a neat heap of 11/2 x 1 x 1 meter size. It is well watered but the water should not seep from below. If possible, this heap is covered with polythene sheet. Sheep temperature of the heap rises upto 78°C second to third day.
Turning of Compost:
The first turning is done on 6th day. About one foot deep compost is scrapped from outside and top and is stacked at one side. Again the same process is repeated till one finds a new stack. Meanwhile a little amount of water is added so that no dry patch remains left.
Sometimes the middle compost becomes white due to excessive heat produced. The white compost is known as ‘fire fang’. The second turning is similar to the first one and is done on 10th day.
The third turning is done on 13th day and 10 kgs of gypsum added during this. This fourth, fifth turnings are done on 16th and 19th day respectively and 10 kgs of gypsum added in each of the two turnings. The sixth turning is done on 22nd day.
If a smell of ammonia comes out, the compost is given two more turnings so that there is no smell of ammonia. However, in this compost the remaining ingredients, 200 c.c. of Malathion and one litre/kg of lintaff, are added to prevent insect infestation.
(ii) Bed-preparation and Cropping:
Compost is now filled in wooden trays, each measuring 1 x 1/2 x 1/4 metre, upto 16-18 cms, is pressed firmly and slightly watered. The trays are arranged one above the other in tiers in pasteurization room. Temperature of pasteurization room is raised upto 60°C and maintained for a period of about two days after which the trays are transferred to production hall, provided with 24°C temperature.
Small pieces of commercially produced spawns are inoculated onto the compost-bed. After spawning the bed is covered with neat, clean and water-wet newspaper. It is important that newspapers should always be wet. A good white cottony growth is observed on the compost-surface below the newspaper after 10-15 days. The newspaper is removed after 20 days and now the trays are subjected to ‘casing’.
Casing denotes the covering of beds with soil. Casing soil can be prepared with three parts ordinary soil and one part of sand (with some peat if available), and of natural pH, i.e., 7. Soil is semi-sterilzed/sterlized before casing at about 20 lb pressure for two hours or by heating in drum at about 90°C temperature or by use of 5% formalin solution.
The casing soil is laid over the beds upto 3/4 – 1″ height. Cased trays are watered by spraying. However, casing of beds is essential as it induces the formation of fruiting bodies.
It takes about a month to make the fruiting bodies appear on beds. Temperature less than 15°C favours fruiting body production, so the temperature in the production hall should be maintained below the said temperature after the fruiting bodies start appearing on beds.
(iii) After Care of the Beds:
Humidity is maintained at about 70-80%. Watering twice a day with a very fine sprayer, keeping its nozzle upside and droplets allowed to come down very slowly, is required, 0.1% lintaff and 0.2% dithane Z-78 spray may be done after 10 days so as to avoid insects and other pathogens etc.