INFLUENCES OF ETHYLENE STIMULATION OF RUBBER TREES (Hevea brasilliensis) ON THE EXTRACTIVES AND FUNGAL RESISTANCE OF LUMBER

INFLUÊNCIA DA ESTIMULAÇÃO COM ETILENO EM SERINGUEIRAS (HEVEA BRASILLIENSIS) SOBRE OS EXTRATIVOS E RESISTÊNCIA DA MADEIRA SERRADA

ABSTRACT

Ethylene stimulation increases the rubber latex yield of live rubberwood (Hevea brasiliensis). Lumber samples from ethylene treated rubberwood (TRW) and from untreated rubberwood (URW) were compared mainly for their resistance to fungi, differences in the chemical composition between TRW and URW, and the antifungal activities of their aqueous extracts. The TRW had significantly higher lignin and extractives contents than the URW, but the TRW had comparatively poor resistance to fungal rotting. The white rot fungus Ganoderma lucidum and the brown rot fungus Gloeophyllum striantum caused in vitro significantly higher mass loss in TRW than in URW. This might be related to the phenolic compounds 2,4-ditert-butylphenol and 4-hydroxy-3,5- dimethoxy-benzaldehyde. The aqueous wood extracts strongly inhibited growth of G. lucidum, with lesser effects on the other fungi tested. Caffeine was detected in the TRW, but not the URW. However, the caffeine degraded so quickly that it had no effect on the 6 and 12 weeks fungal resistances of wood samples.

Keywords:
Ethylene; Extractives; Fungi; Resistance; Rubberwood