Paddy straw mushroom is an edible mushroom of the tropics and subtropics. It was first cultivated in China as early as in 1822. Around 1932-35, the straw mushroom was introduced into Philippines, Malaysia, and other South-East Asian countries by overseas Chinese. In India this mushroom was first cultivated in early 1940’s. In India 19 edible species of Volvariella have been recorded but cultivation methods have been devised for three of them only viz; V. esculenta (Mass) Sing., V. diplasia (Berk and Br.) Sing. and V.volvacea (Bull. ex Fr.) Sing. The optimum temperature and moisture for the growth of this mushroom are 35°Cand 57-60%, respectively. It can be cultivated in North-Indian plains from July to September and in peninsular India from March to November. However, in the hilly areas during the November to January months artificial heating is necessary to raise the environmental and bed temperature but in the plains, artificial heating can be minimized by the incorporation of Melia azadirachta indica and Tamarindus indicus leaves in alternate layers.

A. Morphological Characteristics

                             

Fig. 1. Different structure of V. Volvacea fruiting body                           Table 1. Proximate composition of paddy straw mushroom

This genus takes its name from ‘Volva’means a wrapper; which completely envelops the main fruit body during the young stage. The fruit body formation starts with distinct tiny clusters of white hyphal aggregates called primordia and is followed by successive stages named as ‘button’,  egg’, ‘elongation’ and ‘mature’. Differentiation can be seen first at the ‘button’ stage. At maturity, the buttons enlarge and umbrella like fruiting bodies emerge after the rupture of the volva. The mature fruiting body can be distinguished into the following structures (Fig. 17.1).

Volva: The universal veil is known as volva and it remains more or less distinct in the adult mushroom as a cup like structure at the base of the stipe.

 Stipe: Off-white to dull brown in colour, long, round with a smooth surface and no annulus. The stipe enlarges slightly to a bulbous base, which is encased with a distinct membraneous volva.

 Pileus: The umbrella like fleshy structure attached to the stipe. The size of the pileus is affected by environmental factors, but generally it is around 5-15 cm broad. The ‘annulus’ or ring like structure on the stipe is conspicuously absent in this mushroom.

Gills: The vertical, radial plates on the lower surface of the pileus are lamellae or gills. All gills are with entire margin and fimbriate edges, but the size varies from one quarter of the radius of the pileus to the full size. The top surface of the cap is soft and smooth in texture. The colour of the fully-grown pileus is greyish white with a reddish tinge. The grey being dominant in the centre of the cap. The stipe of the umbrella tapers from the base to the apex and is solid, smooth and white in colour. The stipe is easily separable from the pileus at its junction. The gills are also free from stipe. The pileus is initially well shaped but later becomes convex to umbonate.

B. Nutritive Value

The excellent unique flavour and textural characteristics distinguish this mushroom from other edible mushrooms. The nutritive value of paddy straw mushroom is affected by the method of cropping and the stages of maturation. The proximate composition of paddy straw mushroom is given in Table 17.1. Available data reveal that on fresh weight basis it contains around 90% water, 30-43% crude protein, 1-6% fat, 12-48% carbohydrates, 4-10% crude fibre and 5.13% ash. The fat content increases with the maturation stage and the fully mature fruit body contains as high as 5% fat. The N-free carbohydrates increases from button to the egg stage, remains constant at the elongation and drops at

 

the mature stage. The crude fibre remains at almost same level in first three stages and increases at mature stage. The egg stage contains highest level of protein, which decreases at mature stage. Ash content remains almost similar at all the developmental stages. The straw mushroom is known to be rich in minerals such as potassium, sodium and phosphorus. Potassium constitutes the major fraction of the major elements, followed by sodium and calcium. The levels of K, Ca and Mg remain almost same at different developmental stages, except that of Na and P, which drops at elongation and at mature stages. The contents of minor elements namely Cu, Zn and Fe did not vary much at different stages of development.

The levels of thiamin and riboflavin in paddy straw mushroom are lower than Agaricus bisporus and Lentinula edodes, while niacin is at par with these two mushrooms. At all the stages lysine is the most abundant essential amino acid and glutamic acid and aspartic acid are the most abundant non-essential amino acids (Table 17.2). Tryptophan and methionine are lowest among essential amino acids. The level of phenylalanine increases nearly one fold at elongation stage, while lysine decreases to about half of its value at the button stage. The straw mushroom is comparable to that of the other mushrooms both in terms of amino acid composition and the percentage of essential amino acids in the total amino acids. In fact, paddy straw mushroom contains high percentage of essential amino acids in comparison to other mushroom and the abundance of lysine is very important. The other three amino acids namely leucine, isoleucine and methionine are low in paddy straw mushrooms.

C. Cultivation

1. Conventional method

• Different steps involved in this method are as follows (Fig. .2)

• Preparation of paddy straw bundles of 0.75 – 1.0 kg (80-95 cm long & 12-15 cm wide) preferably from hand threshed paddy.

•  Immersing the bundles in clean water for 12-18 hours in a cemented water tank.

•  Draining out of excess water by placing bundles on raised bamboo or cemented platform.

• Making bed by placing 4 bundles side by side and another four bundles similarly but from the opposite side forming one layer of eight bundles.

• Preparation of second, third and fourth layer by intermittent spawning between first and second, second and third and third and fourth layers.

•  Spawning the entire surface of different layers of the beds leaving margin of 12-

• 15 cm from edges at a space of 5 cm apart.

•  Sprinkling red gram powder over the spawned surface.

•  Using 500 gm spawn and 150 g of red gram powder for a bed of 30-40 kg paddy straw.

• Pressing the bed from the top and covering with clean polythene sheet for maintaining required humidity (80-85%) and temperature (30-35°C).

• Removal of polythene sheet after 7-8 days and maintain a temperature of 28-32°C with 80% humidity.

•  Mushroom will start appearing after 4-5 days after the sheet is removed and will continue for next 20 days.

• After crop harvest the left over substrate can be converted into manure for its use in the fields.

 

 

Table 2. Amino acid contents of paddy straw mushroom                           Fig. 2. Conventional method of paddy straw mushroom cultivation

Note

• For hot regions the width of bed can be decreased by placing first layer of 4 bundles followed by another layer of 4 bundles from opposite side but directly on the first layer. It is to be followed by 3rd, 4th and 5th layers. The 5th layer can be of bundles or of loosened paddy straw.

• The size of beds may vary from 100 x 100 x 100 cm; 60 x 60 x 30 cm; 60 x 60 x 120 cm.

• Alternatively the beds can be prepared with the help of boxes of 80x80x10 cm and 60x40x30 cm size. In this method the material is to be chopped to a uniform length of 20cm followed by filling in box parallel to length of the box. It is followed by soaking of the material along with box in 2% CaCo3 solution for 2 hrs or until the straw becomes dark brown. It is followed by draining of excess water and spawning the substrate at a depth of 5 cm from the sides of the box, followed by plugging the openings with previously water soaked newsprint. The boxes are to be incubated at a temperature of 35 to 38°C with RH of 75% for next 4-5 days, followed by lowering of temperature to 28 to 30°C with 75 to 85% RH along with introduction of fresh air. Use of superfine mist is recommended for maintaining humidity in the room. Spray fine mist of water if drying of beds is noticed,further for good harvest maintain proper aeration, temperature and humidity. This can be best achieved by controlling the ventilation/AHU’s.

 

2. Improved cage cultivation (Fig. .3)

a. Material required

1. Paddy straw bundles         60/Cage

2. Spawn bottle                     2/Cage

Fig. 3. Cage cultivation

3. Wooden cage                     1 No. (1 m x 50 cm x 25 cm)

4. Drum 1 No.                         (100 liters cap.)

5. Polythene sheet                 4 meters

6. Binding thread                     3 meters

7. Sprayer/Rose can                 1 No.

8. Dithane Z-78/Bavistin         1 Pkt. (250 g)

9. Malathion                             1 bottle (250 ml)

10. Dettol/Formalin                 1 bottle (1/2 liter)

11. Dao (Hand chopper)         1 No.

12. Thermometer                 1 No.

b. Methodology

 

Fig. .4. Stages of paddy straw mushroom cultivation

Select dry, fresh and hand-threshed paddy straw free from moulds and leafy portion (Fig. 4). Make 25 cm long and 10 cm thick bundles @ 60 bundles for each cage (bed). Soak the bundles in boiling water for 20-30 minutes followed by draining off excess water.  Disinfect the cage and polythene sheet with 2% formaline or dettol solution. Arrange ten straw bundles uniformly in the cage as the bottom layer and put some spawn grains over and inside the bundles. Put second layer of ten bundles over the first and spawn as before Repeat this till six layers of bundles are achieved or till the entire cage is filled.  Spray 0.1% Malathion and 0.2% Dithane Z-78 solutions all over the bed. Cover with polythene sheet and bind securely with a binding thread.  Keep the spawned cages in a room or under a shed for spawn run. A warm place with temperature around 30°C is helpful for better spawn run.  Remove the polythene sheet after the spawn run is complete. Maintain high humidity in the bed and room till pinheads appear.  Pinheads appear within 10-15 days after spawning. Harvest mushrooms at the egg stage. Continue water spray for the next flush of mushrooms to appear within a week or so. 3. Outdoor method The best place to cultivate paddy straw mushroom outdoor is under shade created by trees or creepers. The steps involved are as follows (Fig. 17.5). ● Prepare a raised platform either using sand or bamboo poles or wooden planks or bricks. ● Prepare bundles of 45 cm length and 10 cm width. ● Soak the bundles in running water or in 2% CaCO3 solution. ● Prepare a layer of bundles (5 bundles x four layers) followed by spot spawning and covering spawn with gram dal powder. ● Lay 4 layers of bundles during summer months and 7 layers during rainy season. ● Topping of bed with 20 cm deep layer of rice straw followed by covering with polythene sheet. ● Remove polythene sheet after 4 days and sprinkle water carefully on 6th day. Water spray can be avoided during rainy season. ● Water should not be sprayed after appearance of mushroom pinheads.