1. INTRODUCTION
Oyster mushroom (Pleurotus sp.)
belonging to Class Basidiomycetes and Family Agaricaceae is popularly known as
‘dhingri’ in India and grows naturally in the temperate and tropical forests on
dead and decaying wooden logs or sometimes on dying trunks of deciduous or
coniferous woods. It may also grow on decaying organic matter. The fruit bodies
of this mushroom are distinctly shell or spatula shaped with different shades
of white, cream, grey, yellow, pink or light brown depending upon the
species.
It is one of the most suitable
fungal organisms for producing protein rich food from various agro-wastes or
forest wastes without composting.
2. OBJECTIVE
The main objective of the exercise
is to present a small scale viable bankable model production unit using
modern technology.
3. BACKGROUND
3.1 Origin
Cultivation of a sp. of oyster mushroom
(Pleurotus ostreatus) was initiated on experimental basis in Germany by
Flack during the year 1917 on tree stumps and wood logs. Growing
technology was perfected in USA by Block, Tsao and Hau.
Cultivation of different varieties
of oyster mushroom was initiated in India in the early
sixties. Commercial cultivation began in mid-seventies.
3.2 Botanical
Description
The oyster mushrooms have three
distinct parts- a fleshy shell or spatula shaped cap (pileus) , a short
or long lateral or central stalk called stipe and long ridges
and furrows underneath the pileus called gills or lamellae. The
gills stretch from the edge of the cap down to the stalk and bear the spores.
The spores are smooth, cylindrical and germinate very easily on any kind of
mycological media within 48-96 hrs. The mycelium of Pleurotus is
pure white in colour.
3.3 Production
Oyster mushrooms are the third
largest cultivated mushroom. China, the world leader in Oyster production,
contributes nearly 85% of the total world production of about a million tonnes.
The other countries producing oyster mushrooms include Korea, Japan, Italy,
Taiwan, Thailand and Phillipines. The present production of this crop in India
is only around 1500 tonnes due to low domestic demand. Another inhibiting
factor is that export demand orders are large and can be met only if a linkage
is developed between producer, cooperatives and exporters.
3.4 Economic
Importance
The economic importance of the
mushroom lies primarily in its use as food for human consumption. It
is rich in Vitamin C and B complex and the protein content varies between 1.6
to 2.5 percent. It has most of the mineral salts required by the human
body. The niacin content is about ten times higher than any other
vegetables.
The folic acid present in
oyster mushrooms helps to cure anemia. It is suitable for people with
hyper-tension, obesity and diabetes due to its low sodium : potassium
ratio, starch, fat and calorific value. Alkaline ash and high fibre content
makes them suitable for consumption for those having hyperacidity and
constipation. A polycyclic aromatic compound pleurotin has been isolated
from P. griseus which possess antibiotic properties.
The spent straw can be re-cycled for
growing oyster mushroom after supplementing with wheat or rice bran @
10-15 % and also for preparing compost of white button mushroom after suitable
supplementation with nitrogen rich horse or chicken manure (sun-dried before
use). The spent straw can be used as cattle feed and also for bio-gas
production, The slurry can be used as manure.
4. MARKET
ANALYSIS AND STRATEGY
4.1 Demand and Supply Patterns
This mushroom is not as popular as
white button mushroom in the domestic market. A few units are cultivating it
commercially for export market. Cultivation of this mushroom on commercial
basis would be more profitable as compared to white button mushroom as capital
costs are low.
The cultivation of this variety of
mushroom is very simple and economical in rural areas where raw materials and
facilities required are easily available.
Marketing of fresh oyster mushroom
does not pose any problem at present due to very low production. However, as
production increases linkage of producers with domestic markets and export
oriented processing units will need to be developed to ensure remunerative
prices to the producers.
Generally, export orders are too big
to be met by a single grower and as such co-operatives have to be encouraged to
pool their produce for trading the crop in a dried powder form in international
markets.
4.2 Import / Export Trends
About 11,797 tonnes of fresh
mushrooms and 4,099 tonnes of preserved mushrooms were exported to foreign
countries viz. U.S.A., France, Ireland, U.A.E., Russia etc. during the period
2001-2002. The quantity of oyster mushroom exported is much lower than that of
button mushrooms which constitute the major share of exports.
4.3 Analysis and Future Strategy
Species of Pleurotus are
cheapest and easiest to grow among all the cultivated edible mushrooms.
Cultivation does not require complicated substrate preparation technique as in
case of button mushroom. The former can be grown on non-fermented, almost fresh
plant residues (agri-wastes containing lignin and cellulose). Substrate
preparation does not require controlled environmental conditions as in case of
button mushroom.
The crop has got a number of
varieties varying in shape, colour, texture and aroma which can be cultivated
throughout the year under varied agro-climatic conditions. Faster
growth rate and early cropping is observed. About 5 to 6 crops can
be taken in a year as the total cropping period is 60 days.
5. PRODUCTION
TECHNOLOGY
5.1 Agro-climatic Requirements
Oyster mushroom can grow at moderate
temperature ranging from 20 to 300 C and humidity 55-70% for a
period of 6 to 8 months in a year. It can also be cultivated in summer months
by providing the extra humidity required for its growth. In hilly areas above
900m. (m.s.l.), the best growing season is during March/April
to September/October and in the lower regions from September/October
to March/April.
5.2 Growing and Potential Belts
The major states in India producing
this mushroom are Orissa, Karnataka, Maharashtra, Andhra Pradesh, Madhya
Pradesh, West Bengal and most of the North Eastern hill states.
5.3 Varieties Cultivated
Among all the cultivated
mushrooms Pleurotus has maximum number of commercially
cultivated species suitable for round the year cultivation. All the varieties
or species of oyster mushroom are edible except P. olearius and P.
nidiformis which are poisonous. Species commercially cultivated all
over the world during summer months includes P. flabelltus, P. sajor
cajo, P. sapidus, P.membranaceous, P.citrinopileatus, P.eous etc. and those
produced during winter are P.ostreatus, P.florida, P.cornucopiae, P.fossulatus,
P.eryngii etc.
5.4 Cultivation Technology
The procedure for oyster mushroom
cultivation can be divided into following four steps:
(i) Preparation
or procurement of spawn
(ii) Substrate
preparation
(iii) Spawning
of substrate
(iv) Crop
management
5.4.1 Spawn Preparation
A pure culture of Pleurotus sp.
is needed for inoculation on sterilized substrate. It takes 10-15 days for
mycelial growth on cereal grains. It has been reported that jowar and bajra
grains are superior over wheat grains.
5.4.2 Substrate Preparation
Oyster mushroom can be
cultivated on a large number of agro-wastes having cellulose and lignin which
helps in more enzyme production of cellulose that is correlated with more
yield. These include straw of paddy, wheat and ragi, stalk and leaves of maize,
millets and cotton, used citronella leaf, sugarcane bagasse, saw dust, jute and
cotton waste, dehulled corncobs, pea nut shells, dried grasses, sunflower
stalks, used tea leaf waste, discarded waste paper and synthetic compost of
button mushrooms etc. It can also be cultivated by using industrial wastes like
paper mill sludges, coffee byproducts, tobacco waste, apple pomace etc.
The popular methods of substrate
preparation are:
Steam
Pasteurization;
Hot
Water Treatment;
Sterile
Technique (Till method);
Fermentation
or Composting; and
Chemical
Sterilization.
5.4.3 Spawning of Substrate
Freshly prepared (20-30 days old)
grain spawn is best for spawning. Old spawn (3-6 months) stored at room
temperature (at 20-300 C) forms a very thick
mat like structure due to mycelium aggregation and sometimes young pinheads and
fruit bodies start developing in the spawn bottle itself. The spawning should
be done in a pre-fumigated room (48hrs.with 2% formaldehyde).
5.4.4 Crop Management
(A) Incubation
Spawned bags, trays or boxes are
arranged in a dark cropping room on raised platforms or shelves for mycelium
colonization of the substrate. Although mycelium can grow from 10 to 330 C,
but the optimum temperature for spawn running lies between 22 to 260 C.
(B) Fruiting
When the mycelium has fully
colonized the substrate, the fungus is ready for fruiting. Contaminated bags
with moulds may be discarded while bags with patchy mycelial growth may be left
for few more days to complete mycelial growth.
While various species require
different temperature regimes all require high humidity (70-85%) during
fruiting. Frequent spraying of water is required in the cropping
room depending upon the atmospheric humidity. Fruit body produced
under humid conditions (85-90%) is bigger with less dry matter while those
developed at 65-70% relative humidity are small with high dry matter.
CO2 concentration
during cropping should be less than 600 ppm. or 0.6%. Sufficient
ventilation has to be provided during fruiting.
5.5 Plant Protection Measures
5.5.1 The crop
is suspect to attacks from flies (sciarid, cecid) spring tails and mites.
Timely spraying with insect specific insecticides is needed.
5.5.2 The crop is prone to fungal
diseases. Several competitor moulds e.g. Aspergillus sp., Cladosporium sp.
and Fusarium sp., Rhizopus sp. have been
reported to occur in the substrate used for
cultivation. Spraying with Bavistin or Benomyl is a
recommended control measure.
5.5.3 The crop is also subject to diseases like yellow
blotch, brown spot and bacterial rot, control measures which are needed
include:
Proper management of
temperature and humidity during growing period.
Regular application of
chlorinated water containing 100 – 150 ppm of freely available chlorine at an
interval of 3 – 5 days
Application of
oxytetracycline and streptocycline.
5.6 Harvesting and Yield
The right shape for picking can be judged
by the shape and size of the fruit body. The fruit bodies should be
harvested before spore release, by twisting so that the stubs are not left on
the beds (straw). It is advisable to pick all the mushrooms at one time from a
cube and the next flush will appear at one time.
More than 500 kg. of fresh mushrooms
per ton of dry wheat or straw can be obtained in case of crop produced in 45-60
days.
6. POST HARVEST MANAGEMENT
6.1 Storage
(A) Short-term Storage
Fresh mushrooms are
packed in perforated polythene bags which are directly sent to the local market
situated nearby. Freshly harvested mushrooms can be stored at low temperature
(0-50 C) for 1-2 weeks without loss in quality in case it is to
be sent to the distant markets.
(B) Long-term Storage
Dried mushroom with 2-4% moisture,
can be stored for 3-4 months in sealed pouches without any change in taste. The
dried produce can be rehydrated in luke warm water (40-500 C)
within 20-30 mins. giving 80-90% of original weight.
6.2 Packing and Transportation
Fresh mushrooms are
packed in perforated polythene bags. Poly pouches containing crushed
ice and overwrapped in paper are put in trays/baskets which are then covered with
thin polythene sheet with sufficient perforation for proper aeration. The
pre-packed pouches (250 or 500 g.) can be transported by roadways in trucks,
buses depending upon the quantity to be transported.
6.3 Marketing
Domestic marketing does not pose a
problem at present because only small quantities are being
traded. As production develops, marketing promotion measures will
need to be undertaken to bolster the demand.
Export potential exists and needs to
be taken advantage of by organizing cooperatives of producers linked to
commercial units for processing fresh mushroom into dehydrated powder for
export.