Development of mycelial systems of Stropharia caerulea and Phanerochaete velutina on soil: Effect of temperature and water potential

Effect of temperature and water potential on extension rate, extra-resource biomass and fractal dimension of Stropharia caerulea and Phanerochaete velutina growing in trays of soil was determined non-destructively with time, by image analysis. S. caerulea responded differently from P. velutina, mycelial extension and biomass production rates of the former being considerably affected by changes in temperature and water potential, with greater aggregation of mycelia into cords at 25 degrees C and at and below -0.02 MPa. These morphological changes were reflect-ed in the fractal dimension values. Mycelial extension of S. caerulea on agar was sensitive to temperatures above 25 degrees and water potentials below -1.3 MPa. This is the first reported work on abiotic effects on fractal dimension of cord-forming fungi on soil, and these results are discussed in terms of the function of mycelial cords and foraging strategies.