HI
1. Selection of Strains
For successful mushroom production, it is necessary for each grower to produce as economically and efficiently as possible the highest quality of mushrooms. This can be accomplished among other requirements, by selecting the best strains which should be high yielding , visually attractive, having desirable flavour, and resistance to adverse climate and pests and diseases. Presently, there are many strains of white, cream and brown varieties in cultivation. The brown variety is the natural mushroom and considered to be the most vigorous form. It tolerates and adverse conditions better than the white variety. A snow white mushroom first appeared amongst a bed of mushroom in the USA and ever since the variety has dominated the mushroom industry throughout the world, although it has a very high limited shelf-life. Where growing conditions tend to be on the dry side and humidity cannot be correctly controlled the brown mushroom should be grown. New superior strains are through selection, hybridization and induced mutations continually introduced by mushroom research laboratories and spawn makers. In India, S 11, S 649 and S791 are the good strains available. These strains were originally introduced from reowned commercial spawn makers, Somycel and darlington. Now these strains are well adapted in the Indian climate and are very popular with the growers.
2. Maintenance of Strains.
Three methods are known by which strains can be propagate. these are multispore culture, tissue culture and mycelium transfer. By periodic subculturing of the mycelium on a suitable agar medium, the span strains can be kept for many years in a fairly good state. However, the frequent subculturing of the strain may result in its degeneration. Maintenence of strain by multisporous culture is only possible if new multispore cultures are compared with the original strain before the original multisporous culture would show much genetic variation. In the tissue culture, small pieces of fruit bodies are cut under sterile conditions and inoculated on a nutrient medium. Mycelium growing out of these tissue can provide the starting point for subsequent spawn production. However, it is commonly observed that tissue cultures often give lower yields than the original cultures. Of these 3 methods, mycelium transfer is most reliable but it is essential that the performance of the mycelium is continually checked in order to detect any degeneration-like slow-growing matted mycelium or fluffy mycelium with abnormal growth rate.
Spawn
The propogating material used by the mushroom growers for planting beds is called spawn. The spawn is equivalent to vegetative seed of higher plant. Quality of spawn is basic for the successful mushroom cultivation.
At present, the pure culture spawn has been the basis of modern spawn production units all over the world. The manufacture of the pure culture spawn is done under scientifically controlled conditions which demand a standard of hygiene as in a hospital operation theatre. Equipment and substrate used for spawn are autoclaved and filtered air is passed during the inocluation ensures complete freedom from contamination.
(a) Manure spawn
Both composted horse-dung or synthetic compost may be used. The composted manure is thoroughly washed to remove such substance in compost which retard growth. The excess water is squeezed out and moisture content adjusted to 60%. The manure is packed in half-litre milk bottles or heat-resistant polypropylene bags os suitable size. The bottles or bags plugged with non-absorbant cotton-wool and sterlized in an autoculave at 1210C for 2 hr or on 2 consecutive days for an hour each. They are then inoculated with a large bit of agar-containing mycelium and incubated at 220-240C in a dark place. the spawn can be used to inoculate fresh bottles or bags to obtain the second generation spawn.
(b) Grain spawn
Ten kilograms of wheat grains are boiled for 15 min in 15 litres of water and then allowed to soak for another 15 min without heating. the excess water is drained off and the grains are colled in sieves. Turn the grains several times with a spoon for quick cooling. The colled grains, are mixed with calcium carbonate. the gypsum (CaSO4.2H2O) and 30 g fo calcium carbonate. The gypsum prevents the grains from sticking together and calcium carbonate is necessary to correct the pH. the prepared grains are filled into half-litre milk bottles or polypropylene bags (at the rate of 150-200 g per bottle or bag) and autocalved for 2 hr at 1210C. After sterlization, the material should have a pH value of 6.5 to 6.7. the bottles are inoculated with grains spawn or with bits of agar medium colonized with mycelium and incubated at 220-240C in a dark place. the mycelium completely permeates the grains in about 2 weeks. Other grains like sorghum and pearlmillet can also be used for spawn making.
(c)Perlite spawn
This was developed by Lemke (1971). Perlite is a mineral which expands at temperature more than 10000C. The ingredients, of the spawn are : Perlite (1,450 g), wheat-bran (1,650 g), gypsum (200 g), calcium carbonate (50 g), and water (665 cc). The gredients are mixed, filled in bottles and sterlized. Thereafter, the process is the same as for grain spawn. Perlite spawn is easy to disperse and can be produced at a cheaper cost. This spawn can be stored for a long time.
4. Compost
The white-button mushroom is grown on a select substrate which provides adequate levels of nutrients to support the crop so that it can successfully complete with other microorganisms. Traditionally, partially-decomposed horse-manure has been the principal medium for providing the required nutrients in artificial cultivation of the mushroom and it is only in recent times that other materials have also been used successfully.
(a) Materials and their functions
(i) Base materials. These includes wheat straw, maize cobs and other similar cellulosic plant wastes with or without horse-manure. Conventionally wheat straw either alone or mixed with horse-manure is the most widely used base material. When wheat straw is not available, straws of the other cereals, like rice of barely may be used. the chief function is to provide cellulose, hemicellulose and lignin in bulk. These materials also provide proper physical structure to the mixture to ensure the necessary aeration for the build up of microbial population and the subsequent spawn growth in the compost. Rice and barley straws are quite soft and decompose quickly, leaving only a little fibre for imparting a proper physical structure to the compost. Therefore the types and quantity of supplement should be discretely utilized at the proper time.
(ii) Supplements. These are for activating fermentation and can be categorised as :
Animal dungs. These include horse- and chicken-manure, the extremely variable manures in composition. Nitrogen cantent may vary from 1 to almost 5% . In addition to nutrients, they contribute greatly to the final bulk density of the compost. cow manure is not considered suitable.
Carbohydrate nutrients. From molasses, wet brewers' grain and malt sprouts, carbohydrates are readily available.
Concentration meals. These materials are usually used for animal feeds and include wheat or rice bran, dried brewer's grain, the seed meals of cotton, soya, castor and linseed. In these, both nitrogen and carbohydrate are available rather slowly. Nitrogen content may vary from 3-12%. The oil and mineral content of some of these may be significance in mushroom nutrition.
Nitrogen fertilizers. Nitrogen in chemical fertilizers (ammonium sulphate, calcium ammonium nitrate and urea) is rapidly released for the quick growth of microbial population.
Materials to correct mineral deficiencies. These are muriate of potash and calcium superphosphate.
Materials to correct greasiness. Gypsum and calcium carbonate serve to precipitate suspended colloidal materials and neutralize greasiness.
The choice of materials within each category is largely determined by cost-factors and their availability locally. Compost prepared from horse-dung mixed with straw are termed as 'natural', whereas they are called synthetic if the base material is used is mainly straw without bulk animal-manure.
Horse-manure
Stable manure with wheat, barley and hay-bedding must be collected regularly from the stables at intervals not more than a fortnight. Manure that has been collected over a long period of time will not ferment properly. It should be an even mixture of droppings and straw well-soaked in urine. Care should be taken that there is no admixture of manure of other animals, garbage or other trash. There should not be excess water because very wet manure cannot be stored satisfactory.
For training please contact the agriculture department.
REgards
Ashwini
