Indoor cultivation of paddy straw mushroom,

Volvariella volvacea, in crates

RENATO GUTIERREZ REYES

Center for Tropical Mushroom Research and Development,

Department of Biological Sciences,

College of Arts and Sciences, Central Luzon State University,

Nueva Ecija, Philippines

The paddy straw mushroom, Volvariella volvacea (Bull.: Fr.) Singer, is

considered to be one of the easiest mushrooms to cultivate due to its

short incubation period of 14 days. It is a tropical species that thrives

best at 30-35°C for mycelial development (Reyes et al., 1998a) and 28-

30°C for fruiting body production (Reyes et al., 1998b). Being

cellulolytic, the paddy straw mushroom can be grown on a number of

cellulosic substrates such as cotton wastes, sugarcane bagasse, rice

straw and stubbles (Chang, 1993; Khan and Dogar, 1991;Reyes et al.,

1998b).

The mushroom is traditionally cultivated on beds made of

uncomposted and unpasteurized bundles of banana leaves or rice

straw, tied at both ends and laid one on top of the other to form a bed.

Mushroom beds which are exposed directly to the sun are covered with

plastic sheets. However, the yield on mushroom beds isunstable and

irregular, since the bed is subjected to microbial contamination and

fluctuating environmental conditions. In order to improve and increase

productivity, a step by step procedure on the indoor cultivation of

paddy straw mushroom using rice straw as the main substrate is here

described. The indoor cultivation method has three salient features:

compo sting, pasteurisation and cultivation insidea mushroom house

using stacks of open wooden crates. Composting is an important

process that allows he microbial decomposers to reduce the tensile

strength of the rice straw. This also prepares the straw for easy

colonization by the mycelium of the paddy straw mushroom.

Pasteurization, on the other hand, is a critical process that eliminates

undesirable microorganisms which may compete with the paddy straw

mushroom during production. It also further renders the composted

rice straw more suitable. The cultivation of mushrooms in growing

houses reduces the sudden fluctuations of temperature and relative

humidity associated with outdoor production which can be hazardous

to growth and fruiting body production. The general procedure for the

indoor

cultivation of paddy straw mushroom is outlined as follows and the

sequence of processing the various stages is given as instructions.

Ingredients

100 kg bale of dry straw

1 kg molasses

0.5 kg complete fertiliser (14% N: 14% P: 14%K)

1.0 kg agricultural lime

10-20 kg spawn for each 100 kg of pasteurised

Compost

Fig 1 Compo sting of rice straw in preparation for the indoor

cultivation of the paddy straw mushroom.

Soaking

Rice straw including stubbles is used as the main substrate for indoor

cultivation of the paddy straw mushroom. Unlike the traditional

method

(bed type) of utilization of this species, rice straw of any type or age

can be utilised. The rice straw is soaked overnight in clean tap water.

Soaking is an important process since it softens the strands of straw

which facilitates the composting process.

Composting

The soaked rice straw is removed (Fig 1) and incorporated with 1%

molasses and 0.5%commercially available complete fertiliser in the

compost pile. The composting period takes 14 days. During the first 7

days of composting, the compost pile is covered with plastic sheets to

induce the growth and proliferation of thermophilic decomposers.

Three days later, the partially composted rice straw is shredded using

a

spading fork to release the residual gases such as ammonia which are

toxic to the growth of the mushroom.

Mix 1% agricultural lime thoroughly into the partially composted

substrates, continuing the composting process for 7 more days to

complete the 14-day period. At the end of composting, the composted

substrate is shredded for aeration.

Wearing a dust mask is advisable when breaking out fresh dry straw\

Crating

Use a wooden open crate measuring 15 x 45 x 60

em. Shred by hand the composted substrate while

packing to fully liberate the residual toxic gases

like ammonia which have accumulated during

composting (Fig 2). The presence of ammonia in

the composted substrate stimulates the growth of

weed mushrooms (Coprinus

cinereus) and thus should be

avoided. The composted

substrate is compressed into

the wooden crates and this

may be facilitated by use of a

suitably shaped press.

Housing of crates

The arrangement of crates in

the mushroom growing

house should not obstruct

the uniform circulation of

hot moist air during

steaming. The steam pipes

should be installed and

extended on the floor of the

mushroom growing house.

Proper arrangement of crates

also permits efficient circulation of air and uniform distribution of light

during incubation and fruit ing. A mushroom

growing house should not necessarily be made

from concrete and can be made from light

materials available in the locality to reduce cost .

Environmental parameters like temperature, air

circulation, light penetration and the distribution

and maintenance of relative humidity should be

taken into consideration.

Steaming

Steam is introduced into the mu shroom house

through the steam pipelines to pasteurise the

composted substrates in the crates. Steaming

should be immediately undertaken after crating, and eliminates the

undesirable microorganisms

which may compete with the paddy straw

mushroom during incubation. A compost

temperature at 60°C for 4-6 hours is best during

steaming. It is advisable to start steaming in the

afternoon, and the temperature of the compost

should gradually go down to 52°C during the

night.

Fig 3 Button stages of the paddy straw mushroom growing on

previously composted rice straw.

Spawning

Prior to spawning, the temperature of the

steamed composted substrate should be no higher

than 30°C. Spawning is a critical process whereby

the viable mycelium of the mushroom, aseptically

grown on agricultural waste such as tobacco

midribs (Reyes, 1991), is inserted into the

steamed composted substrate the morning after

steaming. The spawning rate is 10 to 20 percent

based on the fresh weight of the substrate.

Incubation

Incubation allows the colonization of the

substrate by the mycelium of the paddy straw

mushroom, using an air temperature in the house

at 30°C. Mycelium grows luxuriantly at 35°C and

85% relative humidity and it takes 7-10 days to

fully colonize the substrate. Once mycelial

colonization is complete, observe the formation of

fruiting primordia or initials and introduce

minimal ventilation and light penetration into

the house to stimulate synchronised fruiting.

Lower the air temperature in the house from

30°C to 25°C gradually until the desired

temperature is attained. This is done by

sprinkling fresh water on the floor. This stage

(formation of fruiting primordia) is one of the

most critical stages since poor control of physical

parameters like temperature, ventilation and

light would lead to abortion of the fruiting

primordia. It takes 2-3 days for the complete

development of these primordia into buttons of

marketable size.

Fruiting and harvesting

Harvesting is usually done early in the morning

and late in the afternoon to prevent excessive loss

of moisture and opening of mushroom buttons.

Mushrooms are harvested at the button stage (Fig

3). Care should be observed so as not to damage

the growing buttons which are still developing.

Harvesting may be facilitated by holding the

button and twisting followed by an upward pull.

Sorting and marketing

Clean the harvested mushrooms by removing

the rice straw attached on their bases. Separate

the buttons, which command a higher price than

the open mushrooms and pack them in

perforated plastic bags or styrofoam boxes ready

for marketing. Do not refrigerate the paddy

straw mushroom, which would make it soft and

watery!

Acknowledgement

The support of the Central Luzon State

University Spawn and Mushroom Production

Project and its technical staff (Claire Dalit,

Milagros and Ernesto Tabago, Conrado

Aguinaldo, Reynaldo Pascual, Ernesto Sanchez,

and Oscar Roque) in the Philippines while the

author was the Project Manager is gratefully

acknowledged. Also to the members of Economic

Biology class where mushroom production was

integrated as one of its laboratory exercises.

References

Chang, S. T. (1993). Biology and Cultivation Technology of Volvariella

volvacea. In Mushroom Biology and Mushroom Products, (edited by

Chang, S. T., Buswell, J . A. & Chiu, S.) Hong Kong: The Chinese

University Press.

Khan, S. M. & Dogar, M. A. (1991). Some studies on the cultivation of

Chinese mushroom (Volvariella volvacea) on sugarcane industrial by-

products. In Science and Cultivation of Edible Fungi (edited by Maher,

J . M.). The Netherlands: A. A. Balkema Publishers/Rotterdam.

Reyes , R . G. (1991). Volvari ella spawn substrate formulation and

preparation. In Mushroom Culture and Fertiliser Production. Philippines:

Central Luzon State University Press.

Reyes, R. G., Eguchi, F., Iijima , T. & Higaki, M. (1998a). Physiological

considerations for the efficient mycelial colonisation of Volvariella

volvacea. Journal of Wood Science44: 408-413.

Reyes, R. G., Eguchi, F., Iijima , T. & Higaki, M. (1998b).

Environmentally controlled spawn formulation for fukurotake,

Volvariella volvacea. In Abstracts of the 48th Annual Meeting of th e

Japan Wood Research Society.Shizuoka, Japan.