University of Arizona

Oyster mushrooms can be produced on a wide variety of organic substrates, which enables diverse agricultural crop residues to be recycled/repurposed as mushroom growth medium.  However, not all residues perform equally well and the bioefficiency from one substrate and by a specific mushroom species may not be equal to the bioefficiency from another substrate or by another mushroom species.  This work compares production bioefficiency of pearl oyster mushrooms grown on regionally procured residues from a number of crops around the west.  Substrates evaluated include material with less than 6% protein content, used as the principal carbon source, such as wheat straw, corn stalks and cobs, buffelgrass and other weeds, wood of mesquite, oak, and alder, rice hulls, almond hulls and shells, pecan shells,  Other substrates that are higher in protein, generally more than 12%, are blended into the lower protein content substrate to achieve a nutritious blend for optimal production. These include cotton seed, de-linted or pressed, mesquite pods, alfalfa pellets, sorghum bagasse, soy hulls, tomato vines (from hydroponic tomato production).  Results reveal that changes in the low protein content component of the mushroom substrate has little effect on resulting bioefficiency.  However, changes in the high protein content component has a significant effect and produced significantly more mushrooms with increasing protein content.  Other plant compounds may also have contributed to increasing bioefficiency, such as oil content in de-linted cotton seed.

Mushroom production does not require much lighting and typically production occurs under low lighting for energy conservation.  Often this lighting is supplied as incandescent or fluorescent.  However, CE plant production has converted most lighting to LED for both energy conservation and for production qualities that are affected by different LED spectra.  Fungi respond to similar photoreceptors as plants and likely have similar responses to LED lighting.  In this study, pearl oyster mushrooms were grown under 3 LED illuminations: red (600-650 nm), blue (400-500 nm), and white (broad spectrum).  Light intensity was 5 μmol m^-2 sec for all three illuminations.  Substrates used included straw, cotton seed, and mesquite pods.  At harvest, mushrooms were weighed to determine bioefficiency and caps were measured to determine physical dimensions.  Results revealed that growing P. ostreatus under red, blue, or white LED lights had no significant effect on bioefficiency, on either straw/cotton seed mix or straw/mesquite pod mix.  However, the average cap size for mushrooms produced under red light was less than 40% of the size of mushrooms produced under white or blue light.  Moreover, the mushrooms were produced in clusters that contained 3-4 X as many caps as clusters formed under white or blue light.  Thus, although the bioefficiency was not changed, the morphological characteristics of the resulting mushroom clusters were dramatically different.  This work demonstrates that LED illumination can have significant effects on mushroom qualities of cap size and shape and provides a means for growers to produce mushrooms with specific qualities to meet the demands of the consumer.

Environmental variables have important effects on the growth and development of edible mushrooms. However, published research on the specific effects of different cultural techniques is lacking. This project evaluated the effect of mycelium exposure during fruiting of lion’s mane mushroom,  Hericium erinaceus.  Varied mycelium exposure was created in fruiting bags with rings of PVC pipe of varied diameter; 0.5”, 1”, 1.5”, 2”, and an unrestricted opening (5”) on yield and the quality response variables of Hericium erinaceus in a commercial production setting. Results revealed a significant effect on bioefficiency such that all restricted openings had higher yields than the unrestricted. A further optimal effect was observed in the 1.5” treatment, which had the greatest bioefficiency at 68% after one flush, as well as the lowest variance among reps.  Results for size demonstrated an inverse correlation between average fruit size and hole size, i.e., smaller holes resulted in larger fruit. Optimizing both bioefficiency and fruit size will be of use to gourmet and medicinal mushroom growers. Increasing bioefficiency, reducing harvest variance, and achieving consistent average fruit sizes can all impact operations and sales of H. erinaceus crops.

Insect farming is a growing industry.  It is a principal food source in many cultures and has the potential to supplement food supplies world wide.  Farming insects that feed off of compost or compost-like material increases the economic and environmental sustainability of the industry. The green fig beetle (Cotinis mutabilis, Scarabaeidae) is a native to the Sonoran Desert in the United States and Mexico. This study explored the effects of ten organic waste diets differing in the ratios of four waste types, spent mushroom substrate (Pleurotus), dairy cow manure, spent brewer’s grain, and leaves, on the growth and survivorship of the larvae. Results show that this species yielded highest grub peak weights when fed a diet containing spent beer grains. However, these grubs also had low survivorship. Highest food efficiency conversions were found in grubs that were fed a diet dominated by spent mushroom media. Manure-based compost yielded poor growth and survivorship in these grubs, despite observations of wild beetles laying eggs in compost. A correlation between diet density and peak weight of the grubs suggests that a low-density diet like spent mushroom substrate is a more suitable substrate.