Die Bedeutung ektotropher Mykorrhiza fuer die Naehrstoffversorgung von Nothofagus obliqua. Untersuchungen unter Beruecksichtigung der Boden- und Naehrstoffbedingungen der Nothofagus-Waelder in Suedchile im Hinblick auf Wiederaufforstung und nachhaltige Forstwirtschaft

Abstract

Nothofagus species form the most important native constituents in the temperate humid forests of southern Chile. The presented work concentrates on the evaluation of the relevance of several specific and non-specific ectomycorrhiza for Nothofagus. First, a general survey of ectomycorrhiza found in association to N. obliqua and P. radiata near Valdivia (Chile) is presented. Further work concentrated on the mycorrhizal fungi Austropaxillus boletinoides, Boletus loyo, Austropaxillus statuum, Cenococcum geophilum, Paxillus involutus, Pisolithus tinctorius, and Descolea antartica. The extra-cellular and membrane bound phosphatase activity was determined in cultured mycelium, roots and entire mycorrhiza under different external parameters and growth conditions. Phosphatase activities of mycorrhiza-associations are of increased interest in areas of limited P supply. Extra-cellular and membrane bound phosphatase activity (PA) were quantified at different pH-values (3-7) in isolated cultures of A. boletinoides, P. involutus, P. tinctorius, D. antartica, and C. geophilum, which had been adapted to grow in media with varying concentrations of dissolved P. For the detection of membrane bound PA in fungal hyphae, we compared the pNPP-method with a newly developed method based on enzyme activated fluorescence of ELF-97 substrate and image processed confocal Laser-Scanning-Microscopy. For membrane bound PA, the fluorescence based method not only reproduced qualitatively the results obtained by pNPP, but additionally contributed valuable information about the structure and distribution of the phosphatase spots in the fungi. The ELF-97 method also provided reliable properties to be used for the determination of PA even in mycorrhizal and non-mycorrhizal roots of N. obliqua. In conclusion the observations underline that positive effects of mycorrhiza associations for the plant highly depend on the specific partners, the specific nutrient, and the specific external conditions (pH).