Species richness and composition of arbuscular mycorrhizal fungi occurring on eucalypt trees (Eucalyptus camaldulensis Dehnh.) in rainy and dry season

Abstract

© Beijing Academy of Agriculture and Forestry Sciences. River red gum (Eucalyptus camaldulensis Dehnh.), the most commonly planted eucalypt species globally, has several advantages and is widely used for many purposes, which makes the tree important. Mycorrhizal establishment in eucalyptus has been known for many years, and the benefits of this symbiosis have been commercially explored. The main goal of this research was to assess the diversity and distribution of arbuscular mycorrhizal fungi (AMF) on eucalyptus planted in agricultural fields in the rainy and dry season. Fields were chosen in ten different sites located in four provinces in the northeast of Thailand. Rhizosphere soil and root samples were collected and the number of AMF spores and AMF root colonization were assessed. The number of AMF spores was higher in the rainy season than in the dry season, while AMF root colonization was higher in the dry season than in the rainy season. On the basis of morphological identification of AMF, a total of 35 AMF fungal taxa in eight genera were identified, ten belonging to Acaulospora, one to Dentiscutata, one to Entrophospora, 16 to Glomus, three to Gigaspora, one to Racocetra, two to Scutellospora, and one to Septoglomus. Glomus was the dominant genus followed by Acaulospora. Relative abundance, and frequency of occurrence were higher in the rainy season than in the dry season. Racocetra fulgida was the most common species with a frequency of occurrence of 90% in rainy season, and 80% in dry season. Species richness, Simpson's index of dominance and Shannon-Wiener index of diversity were not significantly different between both seasons.