Authors; CM Ayyub, Saqib Ayyub, Muhammad Ahsan Shakeel, Karim Yar Abbasi (IHS, UAF)
Innovations are going on in agricultural crop production. Developed countries are utilizing recent advances in mushroom production to meet the high demands of the growing population. Mushrooms are basically fungi and have various types. Morels are one of the popular types.
Morels
These are praised for their flavor, texture, and appearance. The part that we eat is the fruiting body of the underground organism called mycelium which has a complex symbiotic relationship with trees. Every spring mushroom enthusiasts, foraging chefs, and an ever-growing group of commercial harvesters hunt these little forest treasures.
Morels vary tremendously in appearance. Their shape can be oblong to bulbous. Their color can be blonde to grey. Their size can be smaller than your fingertip to larger than your hand. Their most identifiable characteristic is what’s typically described as a honeycomb-like exterior. The ‘combs’ or pits on the outside of morels can be tight or loose and form an irregular pattern/corrugation. The inside of morels is hollow and white and up close you can detect a goosebump-like texture. The base of the cap joins to a whitish stem which can be short or tall and the hollow of the cap runs continuously into the stem (this is important to distinguish it from some false morels).
Words can only go so far. They are often described as earthy and nutty, woodsy and toasted. The flavor is rich and deep as opposed, to strong and distinct but not pungent. Their texture is meaty but in a tender way. Certainly a satisfying morsel of protein but not squishy or chewy. Morels don’t offend palates or overpower dishes, and yet they stand above and apart. Every bite of a meal with morels is the best bite.
Absolutely. Morels are loaded with all kinds of nourishment not listed by the required nutrition facts table of Canadian Food labels. As morels tend to grow in rich soils they come packed with vitamins and minerals. While the nutrition can vary based on the soil they are found in, morels will generally contain significant amounts of Iron, Copper, Manganese, Phosphorus, Zinc, Vitamin D, Folate, Niacin, Riboflavin, and a decent dose of Potassium, Magnesium, Calcium, Selenium, Thiamine, Vitamins E and B6.
Morels are not farmed. The complex, symbiotic relationship that the morel mycelium has with trees is difficult to replicate in an artificial environment. It is frequently attempted, even at the commercial level, but if there were a truly reliable method to cultivate morels, global supply would have increased, demand would drop, and the wild morel industry fall apart.
This means that every morel that you eat has been picked by hand in its natural environment. And most likely that someone has traveled a great distance, hiked a great deal, perhaps camped remotely for weeks, battled the elements (mosquitoes, horseflies, rain, drought, etc.), and somehow managed to get that delicate specimen back to the city in decent condition for you to be able to purchase.
Key techniques in the field cultivation of morels
The artificial cultivation of morels has attracted an increasing number of farmers and is receiving the enthusiastic support of governmental organizations and policies in China. To date, the cultivation in farmlands and forest farming is the main morel cultivation patterns in China Cultivation can be performed in various terrains, including plain-hills zones, plateau zones, and mountain zones. Given that dim light is needed and direct sunlight is harmful to the growth of morels, a canopy is necessary. The cultivation process includes spawn production, land preparation, and spawning, an exogenous nutrition supply, fruiting management, and harvesting
Spawn production
Spawn is called seed of mushroom. Similar to the cultivation of numerous other mushrooms, the starter culture (or mother culture), mother spawn, and final spawn are used for morel cultivation. The starter culture can be made from fresh and healthy fruit bodies of morels or obtained from a spawn producer or a laboratory. More agar cultures are then made from this starter culture. These cultures serve to inoculate larger containers (bottles or bags), which can be used to inoculate the final spawn substrate.
The medium used for the morel starter culture is typically potato dextrose agar (PDA) or PDA with hummus. The same or a similar substrate can be used for the mother spawn and the final spawn. The most widely used raw substrate materials include sawdust, wheat, wheat bran, quicklime, and humus. The following recipe can be used: wheat 46%, husk 20%, wheat bran 18%, sawdust 10%, gypsum 1%, precipitated calcium carbonate (PCC) 1%, and humus 4%.
-Glass or heat-resistant plastic bottles are often used for the mother spawn, and heat-resistant bags are used for the final spawn for convenient transportation. Approximately 4500 bags (14 × 28 cm) of the final spawn (∼3000–3375 kg) are used per ha. Numerous spawn producers have recently emerged in China, and the majority of morel growers directly purchased the final spawns. The cost of the spawn is ∼52,500–75,000 RMB per ha (≡US$7620-10880).
Spawning
Morels are aerobic, and loose soil is good for their growth. Soil plowing and removing sundries, such as rocks, are necessary before spawning. Occasionally, quicklime can be used in soil to kill some pests and adjust the pH. The mushroom bed should be ∼80–150 cm wide and 15 cm deep. The distance between the neighboring beds is ∼30 cm.
The spawning for morel cultivation is different from that for most mushrooms given that the morel spawn is sown directly into the cropland or forest, which is similar to the seeding of wheat crops. The season for morel spawning changes based on the different elevations and is mainly from October to the middle of December. Spawning typically begins when the highest local temperature is <20 °C. The soil humidity is maintained at 50–70%. Both sowings in trenches and strewing are used.
Nonnutritive casing soil is spread over the spawn evenly after spawning at a depth of ∼3–5 cm. Film mulching and a canopy can help maintain the temperature, humidity, and dim sunlight.
Exogenous nutrition aiding
The morel mycelia are colonized in the soil after the spawning under suitable temperature and humidity, i.e. <20 °C and 50–70% soil humidity. After 10–15 d, a vast expanse of whiteness appears on the surface of the mushroom bed, which is called a “powdery mildew”. In actuality, this white area is the morel mycelia and conidia that are produced on the soil. Then, an exogenous nutrition bag can be placed in the mushroom bed. The substrates used for the exogenous nutrition bag include wheat, chaff, sawdust, and cottonseed hull. The same recipe can be used as the final spawn, and some recipes are provided in many Chinese patents, e.g. wheat 67%, sawdust 28%, and lime 5% .The composition of exogenous nutrition does not appear to be very strict. The exogenous nutrition bag is filled with a heat-resistant plastic bag and is subsequently sterilized. Holes or a large cut on one side of the bag should be made, and the bag is placed tightly in the mushroom bed.
A 50-cm interval is maintained between each bag, and ∼22,500–30,000 bags per ha were placed. Under suitable temperature and humidity, morel mycelia will grow using the added nutrition and become full of the nutrition bag after 15–20 d. The bags can be removed when the nutrition bag is depleted, which occurs after ∼40–45 d. Exogenous nutrition aiding is necessary for the ascomata development of morels under the current technique. However, the mechanism remains unknown.
Fruiting management
The most important environmental factor during morel cultivation is soil moisture and air humidity. Micro-spray irrigation is necessary for morel cultivation. Timely draining of rainwater and supplementing water during drought should be performed. The humidity of the soil surface should be maintained at >50%.
Before fruiting, the soil and air humidity should be increased. When the temperature increases to 6–8 °C in the spring, the trench between the beds should be slowly flooded to maintain the air humidity at 85–90% and the soil moisture at 65–75%. These conditions will stimulate the differentiation of the primordium of the morels. Cotter also found that flooding is necessary for the outdoor cultivation of morels, and flooding stimulates the morels to feed on beneficial bacteria that are essential for fruiting. However, the flooding mechanism remains to be studied.
Temperature is also important for morel cultivation. The optimal temperature for primordium differentiation is 6–10 °C. Diurnal temperature variations >10 °C stimulate primordium differentiation. Morel fruit bodies cannot grow well at temperatures >20 °C. However, the temperature can only be adjusted by film mulching, a canopy, and spraying and ventilating in outdoor cultivation.
Another important management technique during morel cultivation is pest control. Competitive contaminants include Trichoderma, Aspergillus, Rhizopus, Mucor, Neurospora, Coprinus, and bacteria. Common insects include Limax, mites, springtail, and maggot. All chemical pesticides are absolutely prohibited, but physical and biological control techniques can be used.
Harvesting
When the ascocarp grows to 10–15 cm with an obvious ridge and sinus, the fruit body can be harvested. Fruit bodies can be dried at a low temperature.
Issues and perspectives
True morels are highly prized for their medicinal and nutritional values and are intensively collected around the world by mycophiles. Although outdoor artificial cultivation has been successful in China, knowledge regarding the factors controlling fruit body initiation and development remains far from sufficient. Along with the rapid expansion of morel artificial cultivation in China, several notable problems, including spawn aging and mechanisms of exogenous nutrition, are frustrating to morel farmers. The enhancement of biological research will be helpful for solving those problems and promoting technology for the development of artificial cultivation.
Life cycle and reproductive systems
Determining the life cycle and reproductive systems of Morchella will contribute to the understanding of sclerotia formation and ascocarp production. Morels have a complex life cycle that complicates the process of scaling up cultivation methods to efficient commercial procedures. Although numerous studies have been performed on the life cycle, the information to date is limited and inconclusive.
Conidia production seems to be necessary during outdoor cultivation. However, in pure culture under various conditions, no conidia production is observed. The conidia produced during outdoor cultivation basically cannot germinate. The mechanism by which morels produce the conidia and its function is puzzling.
Morels appear to require the intermediate stage of sclerotia formation before they produce fruit. Growth substrates and their nutritional composition affected mycelial characteristics and sclerotia formation. The presence of a sclerotial stage in morels may be a precursor for ascocarp formation but could also simply be a nutrient storage organ awaiting favorable conditions for ascocarp production. During outdoor cultivation in China, it is not clear whether sclerotia formation is necessary for fruit body development.
Sequencing morel genomes will provide unprecedented insights into fruiting-related genes, the mating system, and genes essential for the sexual reproduction of morels. To date, the genome of only two specie has been completed and reported in the 1000 Fungal Genomes project supported.
Spawn quality
Spawn quality is a key for almost all mushroom cultivation. The cultural morphology of Morchella isolation in different growing media is random and unstable, which highlights the difficulty in spawning quality evaluation. Currently, no quality standard is available for morel spawns in China, and growers empirically judge the quality exclusively based on the number of sclerotia. In fact, the relationship between sclerotia and ascocarp production has not been determined. The insufficient knowledge regarding morel biology, including genetics and life cycle, has resulted in many unsolved problems regarding its spawn.
