FACULDADE DE CIÊNCIAS AGRONÔMICAS CAMPUS DE ...

4
disk inoculation into culture medium colonized and non-colonized (control) by fungi. Evaluations
were performed at 30 and 60 days after inoculation based on the external and internal size of
lesions. In experiment 2, the mycelial growth of P. sanguineus, L. bertieri, Xylaria sp., L. edodes
and S. ostrea was evaluated in bran and sawdust-based substrate, as well as in three culture
media: Potato-Dextrose-Agar (PDA), Malt-Agar (MA) and Sawdust-Dextrose-Agar (SDA), and
at three incubation temperatures, at 23, 27 and 31ºC. In experiment 3, the production of lignolytic
enzymes lacase and cellulase, and other enzymes related to degradation of plant tissues, like
protease, pectinases and lipase was assessed in specific culture media. In experiment 4, mass loss
(%) and chemical features of eucalipt urograndis wood degraded by the soil block method were
evaluated by the P. sanguineus, L. bertieri, Xylaria sp. and L. edodes fungi. Thus, test specimens
were inoculated with the fungi and kept under two moisture regimes, 50 and 100%, and
incubated at 25 ±2ºC. Mass loss was assessed at 30, 60, 90 and 120 days after inoculation. The
chemical features of eucalipt urograndis test specimens were only analyzed at 120 days. External
lesions of plants inoculated with the fungi, assessed at 60 days, were smaller than the lesions at
30 days. The same behavior was noted for internal lesions at 30 and 60 days. A fast colonization
by P. sanguineus and L. bertieri was observed in sawdust substrate and in sawdust-based culture
medium, at 27 and 31ºC; L. edodes e S. ostrea had no growth in sawdust at 31ºC. All fungi
produced the enzymes lacase and cellulases; P. sanguineus was the only one that produced
proteases; only S. ostrea and Xylaria sp. produced lipases; no pectinases production was detected
only by Xylaria sp. In the 50% humidity, the wood eucalypti urograndis mass losses were lower
than 10%, for all the evaluated fungi; at 100% humidity, wood mass losses by P. sanguineus and
L. bertieri were 48,9 and 26 %, respectively; Xylaria sp. mass loss was less than 5%. Through
chemical analysis of decayed wood, it was observed that, in relation to lignin and cellulose, at
50% humidity, consumption by the fungus was in the following order: P. sanguineus, L. edodes,
L. bertieri and Xylaria sp. In 100% humidity, the use of lignin, cellulose and hemicelluloses was
in descending order: P. sanguineus, L. bertieri, L. edodes and Xylaria sp.
_________________________________
Keywords: natural stump removal, Eucalyptus spp., white rot fungus, wood decay.