Background

The oyster mushroom (Pleurotus spp.) also known as “Dhingri” or “Abalone” is one of the popular varieties of edible mushrooms. This mushroom is called oyster mushroom because of the tongue shaped pilens (cap) with an eccentric lateral stripe (stalk). Oyster mushrooms are a diverse group of saprotrophic fungi belonging to the genus Pleurotus (Kong, 2004). According to Croan (2004), these mushrooms are a good source of non-starchy carbohydrates, with high content of dietary fiber and moderate quantity of proteins, including most amino acids, minerals, and vitamins. The protein content varies from 1.6 to 2.5 per cent, and the niacin content is about ten times higher than that of any other vegetable. Moreover, Randive (2012) reported that oyster mushrooms are rich in Vitamin C, B complex, and mineral salts required by the human body. Mushroom production in rural communities can alleviate poverty and improve the diversification of agricultural production (Godfrey et al., 2010). Oyster mushroom can grow at moderate temperatures, ranging from 20 to 30°C, and at a humidity of 55–70 per cent, on various agricultural waste materials used as substrate. The required pH of the substrate for its cultivation is 5.6. Keeping this background, the present study is based on the primary for studying the economics of mushrooms; primary information was collected from Mandi district of Himachal Pradesh (2015-16). This district was purposively selected for the study as it is the leading district in the mushroom cultivation. For the selection of the sample, two-stage random sampling technique was adopted and a sample of 60 growers was selected. The mushroom growers were further classified into two groups; the growers having up to 100 compost bags were categorized as small category and growers having 100 or more compost bags were regarded as large growers. Suitable statistical and analytical tools were employed to accomplish the objectives of the study.

1 Method of dhingri Cultivation

The oyster mushroom (dhingri) cultivation method consists of the steps like substrate preparation, spawning, cropping, harvesting.

1.1 Substrate preparation

Oyster mushroom can be grown on various substrates, namely paddy straw, wheat straw, hulled maize cob, maize stalks, banana pestidostem, wooden log, saw dust and vegetable plant residues. The paddy/wheat straw is widely used for the purpose since it is easily available in most parts of the state/country. Fresh, clean and well-dried paddy/wheat straw should always be preferred. Oyster mushroom is usually grown on chopped paddy straw filled in polythene bags. The paddy straw is chopped in 2.5-4 cm. long and is soaked in water for 12-16 hours. This helps in the removal of surface contamination and the straw absorbs moisture. The wet straw is spread on wire mesh or sloping surface to drain off excess moisture. The wet straw is spread on wire mesh or sloping surface to drain off excess moisture. Sterilization of the straw is required to check weed mould problem and also for higher biological efficiency. Adopting either of the following two methods can do it:

A: Hot Water Treatment: Dip the wet straw in hot water having temperature 70°C to 80°C for 30 minutes. After sterilization straw is placed on wire mesh/sloping surface for cooling and draining of excess water. The moisture content should remain 70 per cent.

B: Chemical Treatment: It is done by using chemical like formaldehyde and bavistin before soaking the straw in water. 100 ml formaldehyde and 5 gm bavistin are mixed in 100 litres of water in a drum or cemented trough. Nearly 10 kg, chopped straw is dipped in this solution and mixed properly. Usually, it is kept for 10 hours soaking so that contamination problems are minimized and the substrate gives higher and almost constant yield. The straw is removed and is placed on wire mesh or sloping surface so that the excess water drains off and the straw retains nearly 70 per cent moisture content. 

1.2 Spawning

Spawning and filling of sterilized straw in the ploythene bag (35 cm x 50 cm, 150 gauge) or polytropylene bags (35 cm x 50 cm, 150 gauge) are done simultaneously. Straw is filled in the bag and pressed gently to a depth of 8-10 cm and spawn is broadcast over it. Similarly, 2^nd and 3^rd layers are put and simultaneously spawn and bags are closed. Few holes are made on each side of the bag for better mycelium development. 10 per cent spawn is required by dry weight of the substrate, i.e., straw. However, it has been found that increase in spawn quantum increases the yield. Spawned bags are stacked in racks in neat and clean cropping room in close position. Temperature 25+40°C and relative humidity 80±5 per cent are maintained inside the cropping room by spraying water on walls and floors. At this stage, room should remain nearly dark and fresh air requirement is also minimum. It takes about three weeks when the bags will be fully covered with white mycelium.   

1.3 Cropping

Once bags are fully white because of complete mycelial ramification, polythene covers are removed. The open blocks are kept in racks about 20 cm apart. There should be 60 cm gap between two rows of racks to working for having a good crop. Two vital factors maintaining proper humidity (80-90%) and congenial temperature (25+5°C) within the cropping room are needed. Too many variations in the temperature and humidity of the cropping room may delay the cropping and also reduce the yield. For first 2-3 days after opening of bag watering on blocks should be avoided. After 2-3 days, light sprinkling of water is given on blocks. This is the time when small pinheads appear. When the pinheads are of 2-3 cm size a little more water is sprayed on blocks. The beds should not be over-watered which may cause rotting of the straw and hindrance to the fruit body formation. The crop bicycle continues for about 60 days. 

1.4 Harvesting

Mushroom should be harvested when they attain size of 6-8 cm. However, the optimum time for plucking is just before starting the inward rolling of the margins of the fruit body. Mushroom should not be allowed to shed spores as it results in poor quality of mushrooms. The fruit bodies should be harvested by twisting them, so that broken pieces are not left out on the bed surfaces, which may cause bacterial infections and rotting of beds. After harvesting, the first flush of the outer layer of the block should be scraped 0.5 to 1 cm. deep. This helps to clean remainants of first flush and to initiate 2^nd flush, which appears in about 10 days of the first one. Similarly, 3^rd and sometime 4^th flush will appear in 8-10 days intervals. However, almost 85 per cent of the crop came out in 1^st, 2^nd and 3^rd flush, hence many growers take only three flushes. The production of mushroom may range between 50-75 per cent of the dry straw used depending upon the care and hygienic programme maintained during cropping period. A small size mushroom farm takes 4 to 5 crops during the season (August to January).

2 Economics of Mushroom Production

The cost of production of 100 compost bags of oyster mushroom has given in Table 1. On small farms the total fixed cost, which included interest on fixed capital and depreciation on mushroom house and implements (iron racks, wooden racks, hygrometer, thermometer, packing machine, exhaust fan, cooler, etc.) used, constituted 81.29 per cent of the total cost. Among variable costs that included expenses on compost bags, medicines, electricity charges, packing materials, labour charges, transportation charges, etc. the expenses on compost bags were the main component and accounted for about 18.71 per cent of the total cost. On large farms fixed and variable cost accounted for 54.60 and 45.40 per cent of the total cost, respectively. On overall farm situation, variable cost was 36.06 per cent of the total cost.

The returns and benefit-cost analysis on different size of mushroom farms have been depicted in Table 2. A cursory perusal of the table reveals that net returns were found to be more on large farms as compared to small farms. It can be seen from the table that the overall production for one crop of oyster mushroom in a year was 210 kg. The net returns per rupee were found to be more on large farms 1.32 as compared to small farms (-0.08). The benefit-cost ratio was observed to be 0.92, 2.32 and 1.83 on small, large and overall farm situations, respectively.

The break-even analysis of sample mushroom farms indicated that for one crop of button mushroom break-even output was obtained as 229 kg, 91 kg and 139 kg mushroom production on small, large and overall categories of farms, respectively (Table 3). In physical terms the break-even point was met with 109, 43 and 66 compost bags on small, large and overall mushroom farms. To conclude, it is estimated that the mushroom growers must place at least 66 compost bags on their farms to meet total cost of production. 

2.1 Factors affecting mushroom production

In order to understand the determinants of mushroom production, regression analysis was done using Cobb-Douglas production function as it gave better fit in accordance with its value of adjusted coefficient of multiple determination R² and number of significant variables. The factors which were affecting the mushroom production were number of spawned compost bags (X₁), labour used in man days per 100 compost bags (X₂), working capital in rupees per 100 bags (X₃) and management index which included maintaining temperature, relative humidity, sanitation and spraying formalin (X₄). The results of regression analysis have been presented in Table 4. The most important variables which influenced the yield of mushroom were compost bags (X₁) and management index (X₄). With 1 per cent increase in compost bags (X₁), the mushroom production would increase by 0.7862 per cent. Similarly, 1 per cent increase in management index measures (X₄) increased the mushroom production by 0.5209 per cent.

3 Conclusions

According to the present study, different kinds of wastes have been proven to be useful for oyster mushroom growing. So, every grower producing oyster mushrooms can make their own best substrate choice from among all those genera or species. The substrates may be useful in the production of a valued protein rich food. Cultivation of oyster mushroom on various agricultural residues offers economic initiatives for agribusiness to examine these residues as valuable resources and use them to produce protein rich mushroom products. Growing mushrooms gives so much satisfaction and produces so much food and income that further use of this practice can result in a great complete contentment of families and villages.The produce has very short shelf-life i.e. of 24 hours. Therefore, efforts are required for creating storage facilities giving a boost to the mushroom economy of the state in general and of the study area in particular. To reap the benefits of mushroom growing the mushroom entrepreneurs must keep atleast 66 compost bags. The mushroom growing by self-help groups should be encouraged. Farmers can undertake mushroom production and marketing through co-operatives.

Acknowledgments

The Author would like to thank the Department of Agricultural Economics, Extension Education & Rural Sociology, CSKHPKV, Palampur, for materials support.

References

Croan S.C., 2004, Conversion of conifer wastes into edible and medicinal mushrooms., Forest Products Journal, 54: 68-76

Godfrey E.Z., Siti, M.K., Judith, Z.P., 2010 Effects of temperature and hydrogen peroxide on mycelial growth of eight Pleurotus strains, Scientia Horticulture, 125: 95-102

https://doi.org/10.1016/j.scienta.2010.03.006

Kong W.S., 2004, Descriptions of commercially important Pleurotus species, In: Mushroom world (Ed.), Oyster mushroom cultivation, Part II., Mushroom growers, handbook, 54-61

Narain R, Jatin S, Satyendra K.G., 2011, Influence of dairy spent wash (DSW) on different cultivation phases and yield response of two Pleurotus mushrooms,  Annals of Microbiology, 61: 853-862

https://doi.org/10.1007/s13213-011-0206-9

Randive S.D., 2012, Cultivation and study of growth of oyster mushroom on different agricultural waste substrate and its nutrient analysis, Advances in Applied Science Research, 3: 38-49