Cultivation of Edible
Mushrooms
Introduction
The cultivation of various species of mushrooms
have been carried out throughout the world. However, in Western cultures,
until the 1970’s, only one species, Agaricus bisporus, was cultivated.
This species is cultivated on a substrate composed of composted horse manure
and straw. However, in Eastern cultures a number of species have been cultivated
that are grown on several different substrates. Tuber melanosporum and
related species, commonly called Truffles, are not cultivated in the usual
sense, but in some circles, they, too, are said to be cultivated. Prior to their cultivation,
mushroom epicures would forage for edible species in nature. Although some
species have been cultivated for at least several hundred
years and longer, the mushroom growing industry is still currently only able to
cultivate relatively few of the known edible species.
Because the knowledge that fungi
reproduced by spores would not be known until the 19th Century, the method
initially used in the early cultivation of mushrooms was far different than
those carried out today. Early cultivation of mushrooms, involved collecting the
fruit bodies of these mushrooms from their natural habitat and taking
them to a vicinity of "fresh" substrate, where their spores would germinate
and colonize the substrate, eventually giving rise to fruitbodies. As was the
realization that diseases could be passed on from individuals to individuals, it
seems likely that the same was believed about mushrooms growing mushrooms.
Initially,
We will discuss some of the better known
species from both Western and Eastern cultures. In these species, several
methods of cultivation is used, composted waste material of various origin,
cut logs, sterilized sawdust in polypropylene bags (heat resistant
plastic bags) and inoculation onto the roots of living trees.
Agaricus bisporus,
Button Mushroom
Agaricus
bisporus is the species that you all know as the "button mushroom,"
and is the most cultivated mushroom in the world, but in Western culture,
it was also the only species available until recently. The cultivation
of this species began around 1650, in Paris France, in areas in which mushrooms
were frequently collected on used compost from melon crops. For approximately
160
years, A. bisporus was grown in open fields. At some point, it was
realized that mycelium, or what is referred to as the spawn of the
mushroom, was what gave rise to the mushroom and could be utilized much
like the seed of plants to grown mushrooms. Another significant discovery
was light was not necessary for the growth of A. bisporus, which
led to its successful cultivation in natural caves, quarries or excavated
tunnels. The advantage of cultivating A. bisporus in caves was the
cool, moist, uniform environment. In 1910, France began growing A. bisporus
in mushroom houses, but caves are still the preferred growing structures
for the production of mushrooms in France.
Cultivation of A. bisporus eventually
spread to England, and by 1865, had reached the United States. At first,
spawn for the mushroom was imported from England, but because of the time
involved in shipping, the mushroom spawn was in poor condition by the time
it had reached the United States and produced a poor quality of mushrooms.
It would not be until 1903 before United States Department of Agriculture
scientists developed its own spawn, thereby freeing the United States
of its dependence upon English spawn, which had caused so many problems.
Louis F. Lambert, a French mycologist,
started the American Spawn Company of St. Paul Minnesota, the first producer
of pure mushroom spawn in the United States. His product was sold across
the country as "Lambert’s Pure Culture Spawn." This spawn received a silver
medal at the Universal Exposition in St. Louis in 1904. A measure of Lambert’s
success was that English spawn was soon being sold under the name "English
Pure Culture Spawn."By 1914, four to five million pounds of mushrooms were
grown in the United States. The production cost to the mushroom grower
ranged from fifteen to twenty-five cents a pound and retailed at forty
to sixty cents per pound, and marketing aimed at the consumers became very
important. Mushrooms were packed in attractive containers to make a good
looking product that sold better.
Growers of mushrooms, at first, were "back
yard" operations and was not their main source of income. From there it
became a large industry in certain parts of the country, with Southeastern
Pennsylvania being the largest center for mushroom production in the country,
a position that it has maintained to this day. In 1924, 85% of the mushrooms
grown in this country were from Pennsylvania. In 1930, the U.S. Census
Bureau revealed that there were 516 growers in the U.S. and that 350 were
in Chester County, Pennsylvania.
Pennsylvania State University also became
a major factor in the growth of the U.S. mushroom industry helping improve
productivity dramatically in the 70’s and 80’s allowing growers to produce
more and more mushrooms per square foot of growing area.
Growing Agaricus bisporus
Although the conditions that are optimal
for growing A. bisporus is known, the actual process is still poorly
understood because the substrate on which it grows is one which is undefined.
The substrate on which A. bisporus is cultivated include horse manure,
wheat straw, corn cobs, several other plant wastes and some animal wastes
such as feather meal and chicken manure. The composting process is a mixed
fermentation involving a range of microorganisms, bacteria and other fungi,
which will degrade some of the complex compounds such as lignin and cellulose.
Due to the biological activities of the microorganisms, the compost will
become very hot, and provide an environment that will be restricted to
only a few microorganisms that will be heat tolerant. When the compost
cools, it will have a consistency similar to that of thick oatmeal and
will provide an environment well suited for mycelial growth of A. bisporus.
Another way in which you can look at the compost, at this stage, is that
it is now A. bisporus’ turn to decompose and colonize the substrate.
Mycelial growth, at this point, is very rapid if maintained at the optimal
temperature of 24 C. However, this temperature will vary according to the
variety, which is being grown. Following growth of mycelium throughout
the substrate, a casing layer, is placed over the substrate. The
casing layer is normally composed rich, clay soil, which is nutritionally
poor, relative to the compost on which the mycelium has been growing. The
casing layer is critical in the fruiting body formation of A. bisporus
and is necessary for the initiation of fruiting. Why this is important
is not known, but without this step fruiting will not occur. The biological
activity of bacteria, various soluble salts, together with the lowering
of the temperature between 14-18 C, will optimize fruiting body production
of A. bisporus. Formation of fruitbodies begin as mycelial strands,
just below the surface of the casing layer, develop "nodules" which are
composed of tightly interwoven mycelium that will eventually develop into
button mushrooms. Fruitbodies of the Button Mushroom are harvested before
their caps expand.
"Varieties" of Agaricus
bisporus
While there is only one mushroom that is
sold as the white Button Mushroom, there are two other mushrooms that are
referable to A. bisporus, but sold under different names. They are
named Crimini
and Portobello,
and both are brown variants of A. bisporus. The Crimini is identical
in appearance to the Button Mushroom except for its brown color. The Crimini
and Button Mushrooms are both harvested before the cap of the mushrooms
are open, and are actually both "button mushrooms". That is they are immature
and have not opened their caps to expose their gills (See picture
of Button Mushroom, above). The Portobello is a mature version of the Crimini
where the mushrooms has been harvested after the cap has expanded and the
dark brown gills are visible. Thus, the Portobello is a more mature and
much larger mushroom than either of the "button mushrooms".
Pleurotus ostreatus,
Oyster Mushroom
This
species is a saprobic fungus that can commonly be found, growing on dead
trees, in nature. Pleurotus ostreatus is common in Europe and North
America, and can now be commonly found in supermarkets in the United States.
However, not as common as A.bisporus. It is large, with a gray to
gray-brown cap that grows to around 5-15cm in its longest dimension. The
stalk of the mushroom is generally white, short and eccentric, i.e. not
centrally attached. The gills are also white. Overall, the mushroom is
fragile, relative to the button mushroom. The normal fruiting period is
during the autumn and winter months when the temperature is approximately
15-20 C. Pleurotus ostreatus was and is a popular mushroom that
is often sought, by those who delight in going out, and collecting their
own mushrooms for consumption. Its cultivation was first described at the
beginning of the 20th Century, on tree logs, but by the late 1950’s, an
important innovation developed, in which sawdust was used as the substrate
material on which the mushroom was to be grown, would become important,
not only in cultivation of Pleurotus, but all cultivated mushrooms
that grow on wood. Although cultivation of
P. ostreatus, began at
the beginning of this century, it would not be until the 1970’s that it
would be found commonly in supermarkets.
The cultivation, as you might imagine,
is quite different from that of Agaricus bisporus. Initially, cultivation
of P. ostreatus was carried out on cut logs, by placing logs, with
fruiting bodies, near the prepared cut logs that had been prepared for
cultivation of P. ostreatus. The spores from the fruiting bodies
would eventually infect the nearby, uninoculated logs and fruiting would
eventually occur. However, this method was inefficient since the cut logs
may become infected with another species of mushroom or not be infected,
at all. To ensure that each log would be inoculated, a means was developed
to inoculate the spawn into the logs. Wooden dowels were placed in a container
in which the P. ostreatus mycelium was growing to allow the mycelium
to grow through the dowels. Holes were then drilled into the cut logs,
to be inoculated, and the infected wooden dowels hammered into the holes.
The hole inoculated with the infected dowel was then covered with parafilm
to prevent drying. In either case, the logs are then kept moist and, within
6-9 months, the fruitbodies will begin to emerge. The logs will continue
to produce for as long as several years. Because of the difficulty in finding
suitable logs for intense cultivation of wood decomposing mushrooms, a
newer method was developed in the 1950’s. This process involves placing
sawdust and a carbohydrate source in a polypropylene bag, which is then
sterilized, cooled and inoculated with the Pleurotus mycelium. The
inoculated substrate is now placed in the dark, and after the mycelium
has grown throughout the substrate, openings are cut through the bag where
fruiting bodies will develop. This process is not only more ecologically
sound, since it utilizes waste material as the substrate on which cultivation
of the mushroom is to occur, but also it shortens the period of fruitbody
formation to approximately two months.
With the successful cultivation of this
species, all species in this genus have been tested for cultivation. Many
of these have since been cultivated. Although P. ostreatus appears
to be a popular cultivated mushroom, I have never seen the appeal of this
mushroom. It has the shortest shelf-life of any cultivated mushroom, and
often will have bacterial and/or fungal contamination within a day or two
of arriving at the market place.
Mushrooms Cultivated in
Eastern Countries
Lentinus edodes,
the Shitake or Forest Mushroom
Lentinus
edodes, the Shiitake Mushroom is as common in Asian countries as Agaricus
bisporus is in the West. Unlike the latter species, L. edodes
is most often sold dried, but because of cultivation of this species now
occurring in the United States, fresh Shiitake is now, commonly, available
at the supermarket. The species is medium size, with a cap diameter of
approximately 2-4" and a stalk that is 4-5" long and approximately 0.75-1"
thick. The cap is brown and "scaly," i.e. with upright warts, while the
stipe is yellowish-white with a prominent, persistent annulus. The Shiitake
has the distinctive advantage of a much longer shelf-like because they
are more commonly sold dried while most other mushrooms are sold fresh.
The methods of cultivation of Shiitake
duplicates that of P. ostreatus, but had occurred much earlier.
The laying of fruiting bodies near freshly cut oak logs in order to cultivate
Shiitake was reliably recorded, from China, approximately 800 years ago.
As in P. ostreatus, it would not be until the late 19th Century
that wooden dowels, with mycelium, would be used to inoculate cut logs.
Presently, sterilized sawdust in polypropylene bags are used in the cultivation
of Shiitake, as was described for P. ostreatus.
The origin of Shiitake cultivation is credited
to Master Wu San Kwung, in Qingyuan. He was regarded as the God of Mushroom
by the local shiitake farmers. During these 800 years, shiitake cultivation
has been the traditional industry for the people of Qingyuan and has spread
to 200 counties in 11 provinces over China. From then on, shiitake had
began the new era of bringing up wealth and health to the people. Qingyuan
is historically regarded as "the Town of Shiitake" and "the Town Of Shiitake
Farmers" and Qingyuan County has held a " China Shiitake Festival", annually.
A great deal of research has been carried
out, in Japan, on the nutritional and medicinal value of the Shiitake.
It is said to be rich in vitamin D2, and has antitumor activity polysaccharides.
Volvariella volvacea,
Paddy Straw Mushroom
The
Paddy Straw Mushroom is probably one that all of you have consumed if you
have ever dined in a Chinese restaurant. Many recipes call for this particular
species of mushrooms. The mushroom is large. The cap, if allowed to mature,
often exceeding 5" in diameter, and is light to dark gray. When young,
the mushroom is entirely enclosed in a white, egg-like structure called
the volva. As the mushroom develops, the stalk will elongate and
push the cap upward, thereby rupturing the volva, leaving only a cup-like
structure at the base of the stalk (see picture on left).
When this species was first cultivated
is unknown, but it is thought to be Chinese, in origin, and is believed
by Chang (1977) to have possibly started as recently as 1822. It is still
cultivated mostly in the subtropical to tropical parts of China or Southeast
Asian countries, where Chinese have migrated. It seems likely that the
introduction of this species to Hawai‘i occurred during the plantation
era, when the Chinese migrated to Hawai‘i to find work. As the common name
implies, the Paddy Straw mushroom was usually grown on paddy straw, but
other plant material are also presently used. Here in Hawaii, it occurs
naturally in compost piles of sugar cane bagasse or wood mulch.
Although the yield is not high, paddy straw
was practically the only material used to prepare the substrate for cultivation
of the Paddy Straw Mushroom under natural conditions, even though other
substrates had been successfully used. These other substrates included
rice straw, dried banana leaves and oil palm bunch waste. However, the
yield utilizing the latter substrate is substantially lower than even that
of paddy straw. Thus, for a long time, this species was not very profitable
as a commercial mushroom. It was not until 1970, when cotton waste was
introduced as a substrate that there was a substantial gain in yield, and
by 1973, cotton waste had completely replaced paddy straw, in cultivation
of this species in Hong Kong (Chang, 1974). This eventually led to the
Paddy Straw Mushroom becoming semi-industrialized in Hong Kong, Thailand
and Taiwan and Indonesia. The cultivation method of this species is more
comparable to that of Agaricus bisporus in that both grown on compost.
The Paddy Straw Mushroom differs, however, in the material that is used
for composting. In the case of cotton waste, the following proportion of
substrates is used: Cotton waste with 4% rice or wheat straw and 4-6% ground
agricultural limestone are mixed and allowed to ferment for 2-3 days. The
composting pile is turned at least once and then pasteurized with steam.
The Paddy Straw Mushroom is presently grown
in a number of Asian countries and the methods vary because of availability
of technology to the growers. In Malaysia, paddy straw continues to be
used as a substrate since 2 million tons of rice straw is produced
annually. In Singapore, paddy straw is again used, but cotton waste,
banana leaves are also used.
Auricularia auricula
and Auricularia polytricha, Ear Fungus
These
two species are two of the most popular edible species. The latter in the
tropics and the former in temperate regions of the world. Auricularia
polytricha was one of the edible fungi in ancient China. The earliest
record of this species was recorded in about 200-300 BC. The species is
now known and has now been cultivated throughout the South Pacific and
Asia. Regardless of where it is utilized, it has a common name which makes
reference to the ear-shaped structure of the fruiting body, Mu-Erh (wood
ear) in China, and Pepiao (ear) in Hawai‘i, just to name a few. The fruiting
bodies are usually brownish to reddish brown and has a consistency of jelly.
In nature, the two species are saprobes that grow on tree logs. Thus, the
cultivation of these species is the same as that of the Shiitake and the
Oyster Mushroom. The cultivation and exportation of Auricularia polytricha,
in Hawai‘i was substantial in the 19th. Century and probably was its first
effort at cultivation of mushrooms.
Tremella fuciformis,
Silver Ear
This
species produces a white, lobed, irregularly shaped fruiting body. It is
a species that has been long utilized as a "herb" to cure many ailments.
In old pharmacological, Chinese books, it is said to cure tuberculosis,
high blood pressure, the common cold and to extend life expectancy. However,
it is also considered a delicacy and, prior to its cultivation, was affordable
only for the tables of the rich. For many years, it was believed that this
species was a wood decomposer as is the Shiitake and Ear Fungus. However,
it is now known to be a parasite on species of Ascomycota that are usually
found growing nearby on the same log as T. fuciformis. A fungus
that is parasitic on another fungus is said to be a mycoparasite.
Thus, in order to grow this species, the host fungus must first be inoculated
into the substrate and allowed to grow for a period of time and the T.
fuciformis is later inoculated and will derive its nutrition on the
host fungus and not from the woody material. This species occurs
in Hawaii, but not commonly.
Flammulina velutipes,
Enoki
The
Enoki is a very small, delicate mushroom. The species is whitish-yellow,
with a cap not more than ¼- ½ " in diameter. The stalk is
approximately 3-4" long and about ¼" thick. It is cultivated on
sawdust medium in large, urn-shaped containers. It would seem to be an
unlikely candidate for cultivation because of its small size, but is commonly
sold in the United States, in supermarkets.
The origin of cultivation of this species
is believed to be in Japan, but its history is even more obscure than other
species, which we have discussed. However, it has been cultivated for at
least several centuries.
Some "Cultivated" Ascomycota
Tuber melanosporum
(Black Truffle) and Related Species
 |
 |
| Tuber melanosporum, The Black Truffle |
Tuber magnatum, The White Truffle:
Sectioned fruiting body on left. |
The truffles are a category onto themselves.
They are undoubtedly the most sought after delicacy among the fungi, with
a market price of approximately $400 per pound . The gathering of
truffles has been recorded as far back as 1600 BC and many early scientist
speculated on their origin and nature in the universe. Theophrastus was
the credited as the first to hypothesize that truffles were "plants" and
came about as the result of rain from thunder storms. Unlike most mushrooms,
truffles are subterranean, i.e. they grow underground. This undoubtedly
led to confusion as to their origin and place in the universe. It would
not be until 1885 that Frank, a German plant pathologist, discovered the
true nature of truffles and their role in the mycorrhizal relationship
with the roots of trees. His theory, however, was not universally embraced
even in the early part of the 20th. Century. In 1903, de Gramont still
believed that truffles were a product of the trees with which they were
associated. Truffles are species of the genus Tuber, which belongs
in the Ascomycota rather than Basidiomycota, where the true mushrooms are
classified. The most highly prized species is Tuber melanosporum,
the black truffle, but other species while not as desirable are by no means
inexpensive. Among other species that are marketed are: T. magnatum,
the white truffle of Piemont and T. uncinatum, the Burgundy truffle.
Truffles are pricey not only because they are highly prized by connoisseur
of good food, but also because of our inability to cultivate them as we
do other mushrooms. The relationship of mycorrhizal fungi with their tree
host is a complex one, and even with the tremendous resources that have
been allocated in studying this relationship, mycologists still do not
understand the environmental conditions that induce fruiting bodies to
form. Various methods of cultivating truffles have been tried, but all
have failed. Thus, for centuries the truffle industry relied upon collections
from nature, but early this century, particularly during the world wars,
demand for truffles fell and prices dropped. Oak trees, which supported
the truffle fungus were cut down and land was developed for more profitable
crops. After World War II demand grew again, however supply was inadequate
and prices became exorbitant. It was the increase in demand that prompted
researchers to find a means for increasing the supply of truffles to meet
demand. It would not be until 1972 that Grente and Delmas proposed the
most logical means of propagating truffles, which was to inoculate the
fungus to the host tree.
In 1977, a great deal of land was put aside
in order to start plantations of various species of European oaks and hazel
trees, which were inoculated with the truffle mycelium. The time required
before the first harvest could be harvested was approximately ten years.
This method of truffle cultivation was successful and has produced a reliable
source for the world's truffle supply. As long as the trees remain healthy,
truffles will continue to be produced without further inoculation of the
fungus. However, other countries desired truffle crops of their own. Capitalizing
on this method, some business people began selling saplings of these various
trees that have been inoculated with truffle mycelium. According to the
September 18, 1984 issue of the Wall Street Journal, this has become a
very competitive and even cut-throat business. Although, the establishment
of such saplings have been very successful in parts of Europe, this is
not always the case, elsewhere.
There have been numerous efforts tried
to grow the host trees, with the truffle mycelium inoculated in the roots,
but outside of Europe, until recently all efforts had failed. In 1987,
New Zealand attempted to grow truffles with imported trees inoculated with
T.
melanosporum. In five years, the first truffles were harvested. This
is half the amount of time required for plantations in France and Italy.
One explanation given as to the shorter waiting period for harvesting is
that New Zealand's unique flora has only a handful of species forming mycorrhizae
with mushrooms - the native beeches, sometimes manuka and some ferns. The
introduction of trees such as Monterey pines and Eucalyptus has increased
the incidence of mycorrhizal mushroom species, but there are still many
areas where such fungi are absent. It is believed that other mushroom species
might compete with the black truffle but because of their absence in New
Zealand, truffles do not compete with other mycorrhizal fungi for a host
and other resources required for their growth. With the success in New
Zealand, Australia began truffle cultivation in 1997.
An additional factor that has aided in
keeping the prices for truffles high, in new Zealand is the time in which
fruiting occurs. In the Norther Hemisphere, the truffles fruits from September
to November. However, because New Zealand is in the Southern Hemisphere,
their seasons are the reverse from ours. Thus, their truffles fruit from
December to February, during our mid-winter and does not compete with the
Périgord black truffle, which fruits from September to November.
In Northern California, where the climate
is similar to France’s oceanic climate (mild and hardly variable), there
was also once an effort to seek out native truffles. It was hoped that
because the similarity in climate, that perhaps T. melanosporum,
or an undiscovered native species of equal quality, would be found. Investors
of this scheme even went as far as to import truffle pigs, into these areas,
to sniff out the truffles. However, no truffles were ever found. Because
truffles grow underground, they must be dug out. The question is, "where
do you dig?" The best way to find truffles is to let pigs, and sometimes
dogs, "sniff" them out. Pigs are the animals of choice, but if they are
used, a choke collar is placed around its neck to prevent them from eating
the truffle once they have dug them out of the ground. After digging the
truffle out, the pig will invariably try to eat the truffle, but the owner
will give the leash a yank and make the pig cough up the truffle.
Morchella esculenta,
Morels
Another,
somewhat successful story involves morel. This is another species of fungi
that is highly prized, but until recently a means of cultivating it was
not known. In this case, all species are edible and apparently equal in
their desirability. For centuries, various methods of cultivation were
tried and failed. The first report of outdoor cultivation of morels was
in 1883, from France, by Roze, in association with Jerusalem artichokes.
This was followed in 1904, by Molliard, who claimed to have cultivated
morels in apple compost. However, there was never any evidence demonstrating
that these men did actually was responsible for the morels that grew, i.e.
they were believed to have arisen naturally. Some observations of specific
environmental conditions, linked to fruiting of morels were tried. For
example, fruiting of morels is often linked to "burned" areas, i.e. where
a forest fire had occurred, or associated with Cymbidium Orchids, or paper
mill sludge. However, attempts to duplicate these environmental conditions
have never yielded morels. Although difficult to fruit, the mycelium of
morels can easily be grown in culture, and in the early 1950’s, a great
deal of effort was spent in producing mycelium, for the "essence" of morel,
to be used as food flavoring. A patent was even taken out on this process,
followed by a number of publications dealing with various substrates that
could be used to grow the mycelium. However, this product was never as
satisfying as having true morels and, with time, lost much of its appeal.
In 1982, Ron Ower published his landmark
paper on the production of morel fruiting body in cultivation.
Although, Ron’s paper generated a great
deal of interest because he was able to repeatedly grow morels, but was
purposely very vague as to the method used to grow the morel. Although
this was a big break through in the dream to cultivate morels, economically,
it was not useful because the yield was far little to be profitable. Gary
Mills, of the Neogene Corporation, in East Lansing Michigan, a Michigan
State University affiliate, who recognized the potential of this process
worked with Ron to try to increase the yield of the morels. After a great
deal of work, in 1985, a patent was granted on the process of morel cultivation.
Unfortunately, even though the process could be demonstrated, repeatedly,
at the Neogene Corporation, attempts to fruit morels in the quantities
necessary to make it economically feasible, have failed elsewhere.
Cultivation of Edible
Mushroom Terms
Agaricus bisporus: Scientific
name for the common “Button Mushroom”, the most commonly cultivated mushroom
in the world.
Button Mushroom: Common name for
A.bisporus
mushroom. Most cultivated mushroom, in the world.
Casing layer: Layer of soil that
covers the mycelium that has grown over the compost.
Crimini: Brown variety of A.
bisporus and differs from the white button mushroom only in its brown
color. It, too, is actually a button mushroom since it is harvested prior
to the opening of the cap of the mushroom.
Morel: Common name given to species
in the genus Morchella, in all known species are edible.
Mycoparasite: Used here to mean
a fungus that is parasitic on another fungus.
Mycorrhiza: The symbiotic relationship
between the roots of plants and a fungus. In the case of those involving
mushroom, the relationship is obligate on the part of the mushroom. If
the tree is not present which the fungus requires, the mushrooms will not
be there. Sometimes the relationship is also obligate in the case of the
host tree.
Oyster Mushroom: Common name for
P.
ostreatus, a cultivated mushroom of western origin. Species is cultivated
on wood or sawdust. Cultivation of this species began only recently, during
the early 20th Century.
Polypropylene bags: Heat resistant
plastic bags used in the cultivation of wood decomposing mushrooms. Sawdust
and a carbohydrate is mixed with water, placed in the bag and sterilized
prior to inoculation of the mushroom spawn.
Portobello: Another brown variety
of A. bisporus, but in this variety the mushrooms are allowed to
mature and are not harvested until the cap has opened and exposed the dark
brown gills.
Shiitake: Common name for cultivated
mushroom, Lentinus edodes, a species that is cultivated on wood
or sawdust. The mushroom is believed to be Chinese in origin and was first
cultivated, in China, about 800 years ago.
Spawn: Mushroom mycelium that is
inoculated into the substrate to begin cultivation of mushroom.
Truffle: Common name given to several
species of Ascomycota, belonging to the genus Tuber. The species
all grow underground and are associated with the roots of certain species
of hard wood trees, forming a mycorrhiza. Thought to be the most prized
and known to be the most expensive mushroom.
Volva: The cup-like remnant of the
universal veil at the base of the stalk of certain species of mushrooms,
e.g.,
Volvariella volvacea, the Paddy
Straw Mushroom.
Questions to Think
About
-
What is the advantage of growing A.bisporus
in caves as opposed to growing it in an open field?
-
What is the function of the casing layer in
the cultivation of A. bisporus?
-
In mushrooms that require wood as their substrate,
why is it better to use sterilized sawdust in polypropylene bags than cut
logs in the cultivation of these mushrooms?
-
The Shiitake has a far longer shelf life than
other cultivated mushrooms. Why?
-
Other than for food, what is another reason
that is given for eating Shiitake?
-
Economically speaking, what is a major problem
in the cultivation of the Paddy Straw Mushroom?
-
In every culture that utilizes Auricularia
polytricha or A. auricula for food, the common name that is
given to these species always includes the word "ear". Why is that?
-
Although Tremella fuciformis (the Silver
Ear) is found growing on logs, in nature, this is misleading. How is the
Silver Ear actually deriving its nutrition?
-
The method used to "cultivate" Truffles is
far different than those used by other species of fungi. Why is that the
case, and do you (in your opinion) think that this is really a method of
cultivation?
-
Although a method has been discovered to cultivate
one species of morels, economically speaking, what is the reason for not
having a full scale cultivation of this species?
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