Coloniza??o micorrízica em plantios de eucalipto

摘要

Mycorrhyzal association is the symbiotic association among some soil fungus and most plant roots. Eucalyptus has the capacity of associating with two types of mychorrizal, arbuscular and ectomycorrhizal mycorrhizal,depending of its age. The objective of this work was to evaluate colonization rates by arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (ECM) and the number of spores of arbuscular mycorrhizal fungi in in commercial plantations of Eucalyptus grandis and Eucalyptus urophylla, at different ages and managements practices, from December 2002 to February, 2004, in eastern region of Minas Gerais, Brazil. In all periods of sampling and at all ages of the plant, it was found both AM and ECM and the colonization general mean by arbuscular mycorrhizal fungi (AMF) was 26%. The average number of spores of those fungi was 374.7 per 100 g of soil and colonization by ectomycorrhizal fungi (EMF) was 20.2 %. Most percentages of colonization by EMF were observed in areas with younger plantations, but it greatest diversity was observed in older plantation areas. It can be concluded that sampling period, age of the plantation and soil management practices affect mycorrhizal colonization and also ECM fungi diversity and succession of eucalyptus with AM-ECM is not a rule and it is strongly affected by management.