ABSTRACT Restoration of degraded sites by using native plants like Plathymenia reticulata Benth. and Melanoxylon brauna Schot. is advisable. However, seedlings of both species, when raised on commercial substrates, may present low survival. This study aimed to evaluate the growth of seedlings under inoculation with arbuscular mycorrhizal fungi (AMF). The seedlings were raised on soil sampled from near an adult plant of the same species. The P. reticulata and M. brauna seedlings were grown with or without the inoculation of a mix of three species of AMF (Rhizophagus clarus, Claroideoglomus etunicatum, and Gigaspora albida), and five doses of P (0, 50, 150, 300, and 450 mg dm-3 of P). All seedlings were inoculated with Bradyrhizobium sp., isolated from each species. After 90 days, P. reticulata inoculated with AMF showed higher growth and nutrient content than those uninoculated, and the maximum plant growth was obtained when received 160 to 280 mg dm-3 of P. On the other hand, no effects of AMF inoculation or phosphate fertilization were observed on M. brauna. For both species, no effect of inoculation was observed on mycorrhizal colonization, and M. brauna, unlike P. reticulata presented a considerable number of nodules. We conclude that inoculation with AMF and P fertilization improves the growth of P. reticulata seedlings but does not promote the growth of M. brauna; presenting the necessity to investigate each species.

The mushroom Pleurotus ostreatus has nutritional and medicinal characteristics that depend on the growth substrate. In nature, this fungus grows on dead wood, but it can be artificially cultivated on agricultural wastes (coffee husks, eucalyptus sawdust, corncobs and sugar cane bagasse). The degradation of agricultural wastes involves some enzyme complexes made up of oxidative (laccase, manganese peroxidase and lignin peroxidase) and hydrolytic enzymes (cellulases, xylanases and tanases). Understanding how these enzymes work will help to improve the productivity of mushroom cultures and decrease the potential pollution that can be caused by inadequate discharge of the agroindustrial residues. The objective of this work was to assess the activity of the lignocellulolytic enzymes produced by two P. ostreatus strains (PLO 2 and PLO 6). These strains were used to inoculate samples of coffee husks, eucalyptus sawdust or eucalyptus bark add with or without 20 % rice bran. Every five days after substrate inoculation, the enzyme activity and soluble protein concentration were evaluated. The maximum activity of oxidative enzymes was observed at day 10 after inoculation, and the activity of the hydrolytic enzymes increased during the entire period of the experiment. The results show that substrate composition and colonization time influenced the activity of the lignocellulolytic enzymes.

A associação micorrízica é advinda da associação simbiótica entre alguns fungos do solos e da maioria das raízes das plantas. O eucalipto possui a capacidade de se associar com dois tipos de micorrizas, a micorriza arbuscular e a ectomicorriza, o que depende muito da sua idade. Este trabalho objetivou avaliar a taxa de colonização por fungos micorrízicos arbusculares (MA) e ectomicorrízicos (ECM) e o número de esporos de fungos micorrízicos arbusculares em plantios comerciais de Eucalyptus grandis e Eucalyptus urophylla, com diferentes idades e manejos, no período de dezembro de 2002 a fevereiro de 2004, na região leste de Minas Gerais, Brasil. Em todas as coletas e em todas as idades dos plantios, foram encontradas MA, e ECM e a média geral da colonização por fungos micorrízicos arbusculares (FMA) foi de 26%. O número médio de esporos desses fungos de 374,7 por 100 g de solo e a colonização por fungos ectomicorrízicos (FECM) de 20,2%. As maiores porcentagens de colonização por FECM foram observadas em áreas de plantios mais jovens, mas a sua maior diversidade foi observada nas áreas de plantios mais velhos. Conclui-se que a época de coleta, a idade do plantio e o manejo do solo afetam a colonização micorrízica e também a diversidade de fungos ECM e que a sucessão de eucalipto com FMA-FECM não é regra e é muito influenciada pelo tipo de manejo.

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.