![]() Nevertheless, the interplay between light and calcium concentrations continues to be a subject of great interest. Just as strains of Shiitake differ n their fruitir.g cycles, I suspect that the "calcium factor" in triggering Shiitake formation may be strain specific. Calcium is naturally present in woods in sufficient quantifies to allow fruiting. Hg/mg.) levels, the wavelengths most stimulatory for primordia forma on were between 400-500 nanometers, what we know as blue to ultraviolet light. Lack of light causes Oyster mushrooms to malform into coral-like structures. Leatham and Stahlman (1987, 1989) con ducted trials with Shiitake on chemi :ally defined media which showed that the absence of calcium made the mycel:um unresponsive to light stimulation. growing room which also gets supplemental natural light through a row of diffusion panels.) For specific light requirements, please consult the growth parameters for the species being cul' wated. long, "Daylight'" 6500 Kelvin fluorescents to light each 1000 sq. For most species, light levels between and 50-1000 lux and 380-480 nanometers ¿great! to blue) seem most stimulatory to primordia formation. Modest light is not harmful to developing mushroom mycelium it seems unaffected by its presence Direct sunlight or high intensity exposure is harmful The fluorescent lights used in indoor facilities do not inhibit mycelial growth, and in some circumstances may simulate early pri mordia formation. ![]() In these cases, cultivators resort to providing the lighting necessary to the most sensitive of the gourmet mushrooms, the Pleurotus species. Specific photo-periods and spectral frequencies have not yet been established foi all mushroom species. Indirect natural light, or the dappled light filtering through a forest canopy, is considered ideal for woodland mushrooms. Ideal light conditions-intensity and wavelength-vary with each species and strain. Light controls stem elongation and cap development. Light: In nature, light acts as a signal alerting the mycelium to an open-air environment where, should mushrooms form, spores can be spread into the air. In most cases, the critical temperature plateau occurs within 2-4 inches of the surface, the region supporting the ere a.ion of primordia. Air temperature is adjusted upwards or downwards to affect the desired change When air temperature :s changec, a lag time follows, often for 24-72 hours, before the substrate temperature adjusts to he prerequisite level. Note that the temperature thresholds listed for each species are what cultivators call the bed. This s the i leal time to synchronize the other factors favor able to mushroom formation. After colonic on is complete, heat generation abates, and internal temperatures naturally dec :ie to nearly equal with air temperature. As a substrate is being colonized with mycelium, heat is released a a by-product. Since mush room formation is primarily a surface phenomena the atmosphere of the growing room has to be altered to affect a temperature change in the substrate. Temperature: Many strains will not form mushrooms unless temperate is dropped or raised to a critical plateau For most strains, a temperature drop is required. Air exchange should be adjusted specifically to lower CQ, to the specified levels outlined for each species in 'he following growth parameters. CO, levels should be belc / 1000 ppm, ideally below 500 ppm for maximum mushroom formation. Humidity should be measured in at least three locations in the free air spaces directly above the mycelium-pen neated substrateĪir Exchange: Air is exchanged to precipitously lower carbon dioxide and io suddenly provide oxygen. Once primordia form, a gradual reduction of humidity from 100% to 90-95% usually is beneficial. Important when aonal mycelium is first exposed to the growing room environment. ![]() A Magic Mushroom (Psuocybe cubensis) fruiting from casev' grain. Moisture: C"-ect watering is applied, coupled with a constant, controlled rate of evaporation to mahiain high humidity between 95-100%. The four major environmental factors operative in an initiation strategy are: moisture, air exchange, temperature and light. An r it ation strategy can be best described as a shift in environmental variables, triggering the formation of mushrooms. B y far the most crical step is that of primordia formation, called the initiation strategy.
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