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The rise in temperature is an important event during the composting of lignocellulosic materials and has to be controlled and regulated to improve the biodegradation. Phase I mushroom composts were incubated under environmentally controlled conditions. When the temperature was pre-set at 65°C and then later at around 80°C, the microbial respiration and the biodegradations were hardly affected. However residual activities due to thermoresistant bacteria were still measured after 68 h at a constant temperature of 80°C. Significant changes in nitrogen resources were observed: loss of nitrogen from microbial products, an increase in the proportion of nitrogen in non-hydrolysable and stable forms, and an increase in volatilisation of ammonia. These changes were mainly due to physico-chemical mechanisms associated with disturbances in the structure of the microbial community.

Summary — Eight fungicides used on wheat were checked for their toxic effect in vitro on the mycelial growth of 3 strains of the edible mushroom Agaricus bisporus and 3 isolates of thermophilic fungi active in mushroom composting. At concentrations < 2 ppm, captan, maneb and chlorothalonil were not found to be toxic. Only tebuconazol significantly limited the radial growth of A bisporus mycelium. The

The influence of cultivation substrate (compost) quality as an environmental factor was determined on three traits of interest in the selection of Agaricus bisporus strains. Induced variations in compost nitrogen and copper content were used to modify compost quality. Compost effect and strain × compost interaction were found to be significant for bacterial blotch susceptibility, natural cap colour and yield. Two classes of strain not affected by compost quality were identified in a group of commercial and wild strains: white mushrooms susceptible to bacterial blotch and brown resistant mushrooms. The relation between compost composition quality and mushroom quality traits are specific for each group of strain. Nitrogen and copper content of composts were of interest as indicators of compost quality but other factors have to be evaluated for better compost characterization.