Site and seasonal influences on the fungal community on leaves and stems of Pinus and Quercus seedlings in forest nurseries

摘要

Fungal assemblages present in nursery seedlings were surveyed, aimed to evaluate influences of site, season, host and plant part. Four sampling sites were selected; three of them were sampled twice, in spring and autumn. Needles/leaves and stems werecollected from five host species: Quercus ilex, Q. pyrenaica, Pinus pinea, P. nigra, and P. sylvestris and surface-sterilized with sodium hypochlorite. A total of 1557 fungal strains, pertaining to 59 'species' or morphological types, were recovered. Thedominant species, with higher isolation frequencies were Alternaria alternata complex, Cladosporium cladosporioides, Phoma sp., Clonostachys rosea, Ulocladium sp., Trichothecium roseum, Cytospora leucosperma, and Rhizopus sp. Median values of fungal species per observation differed significantly among the sites. The diversity of fungal species was significantly higher in the spring, and isolation frequencies for most of the dominant species were also dependent on the season, however the number of isolates per sampling was not influenced by the season. The results showed that the most frequent species (Alternaria alternata complex and Cladosporium cladosporioides) were associated with autumn observations, whereas higher frequencies of saprobic fungi (Aspergillus niger, Ulocladium sp. and Cytospora sp.) were found in spring.