EFFICIENCY OF ARBUSCULAR MYCORRHIZAL FUNGI IN PROMOTING GROWTH OF SEEDLINGS OF SOME CALCIFUGE EUCALYPTUS SPECIES IN A CALCAREOUS SOIL

These paper present informations on the role of soil microbiota with a special relevance to arbuscular mycorrhizal fungi on growth of eucalypt species in calcareous soil. Most species of this genus are calcifuge. Four Eucalyptus species were used in this study: three are calcifuge and one calcicole. Seedlings have been grown in soil sterilized or not. Soil was collected around mature trees, in a stand presenting a calcareous soil. Seedling growth (height, stem dry weight, root length and number of secondary roots) and mycorrhization were monitored over 80 days. Results revealed that growth of the calcifuge species was not affected in non sterilized soil but severely hampered in sterilized soil. Seedlings of the calcicole Eucalyptus species do not present chlorosis in sterilized soil but its growth was significantly enhanced in non-sterilized soil. All seedlings grown in non sterilized soil were mycorrhizal but rates were higher for calcifuge species. These results suggest that arbuscular mycorrhizal fungi have a beneficial impact on tolerance of calcifuge Eucalyptus. Species to soil calcium carbonate and promote their growth