Structure and development of mycelial cord systems of Phanerochaete laevis in soil

Abstract

The total length of a mycelial cord system of Phanerochaete laevis , present in the surface soil and litter of a deciduous woodland, increased from 1415 to 1479 cm over a period of 13 months. This increase was accompanied by loss of 270 cm from the central parts, and a corresponding proliferation at the periphery of the system. Mycelial growth from colonized beech blocks (approx. 8 cm 3 ) into 30 cm long glass tubes containing γ-irradiated soil showed little differentiation of cords and usually ceased well before reaching the ends of the tubes. By contrast, in similar tubes containing unsterilized soil, well-defined cord systems were formed which reached the ends of the tubes within about 15 weeks. These developed from an advancing front of more or less constant width containing numerous finely-branched cords. Following lysis at the rear of this front a relatively few large cords remained which were still connected to the blocks. Light inhibited mycelial development in the tubes in both γ-irradiated and unsterilized soil. After 15 weeks in the tubes wood blocks from γ-irradiated soil had undergone a greater loss in dry weight (22–27% compared with about 15%) and had a higher nitrogen content than those from non-irradiated soil.