Yield, mushroom size and time to production of Pleurotus cornucopiae (oyster mushroom) grown on switch grass substrate spawned and supplemented at various rates.

To find a cost effective alternative substrate, Pleurotus cornucopiae 608 (yellow basidiomata) was grown on: (1) chopped, pasteurized switch grass (Panicum virgatum, 99%) with 1% ground limestone and (2) a mixture of pasteurized cottonseed hulls (75% dry wt.), 24% chopped wheat straw, and 1% ground limestone (all ingredients wt./wt.). The substrates were spawned at various levels (2.5%, 3.75% or 5% wet wt., crop I) and non-supplemented or supplemented with commercial delayed release nutrient (Campbell's S-41) at various levels (0%, 1.5%, 3%, 4.5%, 6%, 7.5% and 9% dry wt., crop II). Maximum yield (weight of fresh mushrooms harvested at maturity) was obtained on cottonseed hull/wheat straw substrate at a 3.75-5% spawn level and 6% S-41 supplement. On switch grass substrate, increasing spawn levels and supplement levels stimulated yields in a linear fashion. However, maximum yields were only 46% or less for those of similar treatments on cottonseed hull/wheat straw substrate. Yields were three times higher on switch grass that was harvested after the grass had senesced (winter; beige color) compared to material that was harvested when the grass was green (summer; time of flowering). Additional physical processing of the material, such as milling, may improve yield potential of this material.

Vacuum-soaking of wood chip shiitake (Lentinula edodes) logs to reduce soak time and log weight variability and to stimulate mushroom yield.

Synthetic logs were vacuum-soaked or regular-soaked to determine the effects of soaking on yield and mushroom size, log weight variability and water distribution within the log. Yields (g/log) from substrates vacuum-soaked were higher by 26.7%, 18.6% and 35.8% (mean = 27.2%) for crops I, II and III, respectively, when compared with regular-soaked. However, mushroom size averaged only 11.2 g for vacuum-soaked logs vs 17 g for regular-soaked logs (51.8% larger for regular-soaked). The time required for vacuum-soaking logs was generally less than 3 min, compared with regular-soaking times ranging over 3-15 h. Water tended to accumulate more in the outside zone in the vacuum-soaked logs, compared with regular-soaked logs. Mean moisture contents for crops I and II for outside, middle and interior zones of vacuum-soaked logs were 66%, 47.5% and 42.2%, respectively, while regular-soaked logs for the same zones were 62.4%, 52.1% and 50.9%, respectively. Vacuum-soaked log weights had lower standard deviations than weights for regular-soaked logs in four out of six soaks, indicating a more uniform soaking process.