Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Graduate School, College of Agricultural Sciences at the Pennsylvania State University
Commercial production of Agaricus bisporus is dependent upon a substrate prepared by composting. Traditional composting is associated with a number of environmental problems such as the emission of offensive odors and waste water run-off during handling. In addition, after the production of a crop of mushrooms, there is the problem of disposal of spent mushroom substrate (SMS). Thus, preparation of a suitable substrate for mushroom production without the generation of offensive odors and the possible re-use of SMS for the production of a second crop of mushrooms are desirable. The goals of this research were to evaluate two substrates for the production of A. bisporus: a) non-composted substrate (NCS) consisting of red oak sawdust (28%), millet (29%), rye (8%), peat (8%), ground alfalfa (4%), ground soybean meal (4%), wheat bran (9%) and CaCO3 (10%) and b) SMS. Treatments included 1) NCS and SMS alone and in combination, 2) spawn carriers, 3) strains, 4) supplements, 5) time of supplementation, and 6) substrate moisture content. The substrates were sterilized in very high porosity filter plastic bags and then spawned and incubated. Mushrooms were harvested for two flushes and yield, biological efficiency (BE) and mushroom size were determined. The highest yield and BE (27.2 kg/m2, 144.3%) were from 1:1 NCS/SMS spawned with casing inoculum (CI) and supplemented with 10% Target® at casing. The largest mushrooms were obtained from NCS spawned with CI and supplemented at spawning with 3,000 mg/kg Micromax® (57.3 g/mushroom). Mushrooms containing the highest solids content (9.9%) were harvested from NCS spawned with CI (60% moisture content). Supplementation of NCS/SMS with Micromax®, a commercial micronutrient,
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had no significant effect on yield and BE. However, the addition of 0.9% Micromax® (d.w.) to NCS significantly increased yield by 72% (from 8.5 kg/m2 to 14.6 kg/m2). This work shows the potential to produce relatively high yields on NCS or on mixtures of NCS/SMS and that a combination of supplements that contain protein, carbohydrate and micronutrients added at spawning or at casing resulted in improved mushroom yields.