The following points highlight the two main methods used in cultivation of mushrooms. The methods are: 1. On Paddy Straw 2. On Wood Log.
Method # 1. On Paddy Straw:
Paddy straw mushroom— Volvariella volvacea (Bull. ex. Fr.) Sing, cultivation comprises of the following stages preparation of spawn; preparation of mushroom bed; spawning and watering of mushroom bed; mushroom crop production; and harvesting of mushrooms.
i. Preparation of Spawn:
Mushroom spawn can be simply defined as a medium impregnated with mushroom mycelium and serves as the ‘seed’ or ‘inoculum’ for mushroom cultivation. It is actually a fibrous mass of mycelium growing on dead organic matter. Spawn may be obtained either by tissue culture method or by pure culture from germinating spores obtained from desired mushroom fruit body.
The entire process of preparation of spawn should be aseptic from the beginning to the end.
Spawn may be: grain spawn and straw spawn.
Grain spawn is prepared with grains of rye, sorghum or wheat cooking in water and sterilizing in autoclave for 30 minutes, inoculating with pure culture of desired mushroom and incubating at proper temperature. When the mycelium has ran over the whole surface of the grain, the spawn is ready for use.
Straw spawn is prepared with paddy straw or wheat straw cutting into suitable pieces, soaking in water for 5 to 10 minutes, mixing in 2 per cent lime and proceeding further as done in case of grain spawn. Preparation of spawn is usually done in glass bottles.
ii. Preparation of Mushroom Bed:
At first prepare a bamboo or wooden frame of suitable size, say about 1 sqr. metre. Then prepare paddy straw bundles from un-crumpled paddy straw of not more than one year old from which leafy material has been removed. Each bundle of straw weighing around 1 kg. should be tied at both ends by strings.
Clip off unequal parts of straw at both ends of each bundle. Dip 8 such bundles in water in a tank for 18 to 24 hours. Take them out from the tank and spread on the frame prepared earlier and this constitutes the first layer of the mushroom bed.
iii. Spawning of Mushroom Bed:
Spawning is the process of planting spawn on the mushroom bed materials. Remove the spawn from the glass bottles in which spawn has been prepared. Break it into small pieces by crushing and crumbling with the fingers. Spawning should be done on the first layer of straw bundles by broadcasting keeping about 4 to 6 inches margin all around the bed un-spawned.
Gram or pigeon pea powder should now be dusted over the spawned area.
Treatment of the first layer of straw is now complete. During the spawning period proper temperature and humidity should be maintained. Never let the bed surfaces dry out. As the spawn grows, it produces heat which contributes to the water loss. Water mushroom bed lightly with water sprinklet.
Prepare a second layer of 8 straw bundles as above and place on the first layer arranging the straw bundles crosswise with the first layer to facilitate proper aeration of spawn.
The second layer should be spawned and treated with gram or pigeon pea powder in the similar manner as done in the first. In all, mushroom bed of 4 layers of straw are to be arranged in one frame following exactly the same procedure so that the straw bundles are arranged crosswise. All the 3 layers of Straw should be spawned and treated with gram or pigeon pea powder in the same manner.
But the 4th layer should not be spawned or treated with gram or pigeon pea powder. It should be gently pressed and tied with a rope with the 3rd layer. Then place a polythene or plastic sheet on the mushroom bed in such a manner that it does not touch the straw bundles.
iv. Watering of Mushroom Bed:
The mushroom bed should be watered once or twice daily to keep the temperature range between 35° and 40°G and moisture suitable for the development of mushroom fruit bodies.
v. Mushroom Crop Production:
Small mushroom buttons (primordia of fruit bodies) will start appearing within 10 to 15 days after spawning. But it will take 4 to 6 weeks to get a crop of mushroom. Mushrooms appear in- rhythmic cycles which are called “flushes” or “breaks”.
vi. Picking of Mushrooms:
During picking, mushrooms should be lightly twisted so that neighbouring young ones are not disturbed.
vii. Precautions of Mushroom Cultivation:
Precautionary measures of mushroom cultivation are: during cropping period suitable temperature, humidity and ventilation of mushroom bed should be maintained; insecticides like Linden or Gammexane powder should be sprinkled to check insect incidence; growth of any other fungus in the mushroom bed should be checked by spraying Captan and Zineb (0.2 per cent); and during picking of mushrooms immature fruit bodies should not be touched.
Poor cropping of mushrooms and production of abnormal fruit bodies may be at times due to virus infection. Symptoms like watery stipe and die-back are also produced as a result of virus infection.
Method # 2. On Wood Log:
Cultivation of mushroom—Pleurotus sajor-caju (Fr.) Singer on wood logs of Mangifera indica may be done in the following manner.
Prepare logs 60 cm. long and 2.5 to 3.75 cm. thick. Dry the logs in Sun for 15 days and then keep them immersed in water for 7 days. Make holes (2cm. diameter each) on the logs at 7.5 cm. apart from each other. Fill in the holes with wheat grain spawn of Pleurotus sajor-caju.
Keep the spawn inoculated logs vertically in a large earthen pot and cover them with a polythene bag and incubate at room temperature of 20° to 30°G. Watering of logs should be done at intervals of 5 days. Remove the polythene bag as soon as the mushroom buds appear on logs and continue to water the logs daily. Two flushes of mushroom fruit bodies appear in course of 80 to 90 days, the yield being higher in the first flush.
Large scale cultivation:
Out-door cultivation of mushrooms can be done in a large shed or in a permanent building where bed space can be increased by erecting tiers of wood, allowing 75 cm. to 90 cm. space in between each.
For a profitable mushroom growing most important feature is careful preparation of bed with nutrient substrate. The commonly used crude nutrient substrate is horse- dung manure and a composting mixture of chopped wheat, paddy straw and some fertilizers like superphosphate, urea and ammonium sulphate.
The beds should be filled from top tier downwards and made up to the same depth with nutrient substrate. Sterilized silt clay loam soil should be added to the beds followed by careful labelling of bed surface. All doors and ventilators should be left open for several hours.
Small pieces of spawn about the size of a walnut should be inserted pressing firmly into the compost. A fairly humid atmosphere and depending on the genus of mushroom used, a temperature range of 10° to 15°G encourage profuse growth of mycelium after three weeks. The beds should be regularly dusted with Gammexane powder to take precaution against insect attack.
Small buttons of mushrooms will appear after 5 to 8 weeks from the date of spawning. Mushroom beds should now be carefully sprinkled with water. In about 7 to 10 days mushroom buttons develop into mature mushrooms. Mature mushrooms should be plucked taking care so as not to loosen the base of the stalks.
Depending upon the food value of the compost, 3 to 4 flushes of mushrooms may be plucked at the end of which the compost may be used as garden or field fertilizer.
Prospects of mushroom cultivation:
Besides being rich in vitamins B and D, mushrooms contain protein and minerals many times more than common vegetables. Again unlike vegetables, the entire mushroom can be used as food. As a source of protein, mushroom is richer than many vegetable sources.
Hence with richer source of protein, mushroom can be a good substitute for combating protein deficiency. Being entirely devoid of starch, the mushroom is an exceedingly useful food for diabetics and also for any one not wishing to add to one’s weight.
Above all, mushroom lends itself particularly well to food stuff production independent of soil, and can produce more than six generations per year with low cost of cultivation. Besides these, the raw materials for culture medium are easily available with low cost. Even the spent manure may be reused in the field or garden as fertilizer and paddy straw as cattle feed.
Keeping in mind the above aspects of mushroom cultivation every effort should be made to popularize:
(a) Mushroom eating habit,
(b) Mushroom cultivation, and
(c) Mushroom marketing which will by and large release pressure from the consumption of conventional food stuff and will go a long way to solve the problem of food crisis to a great extent.