Assessment of the durability of a lesser known species (Borassus aethiopum Mart.) against termite and fungi from different ecozones in Nigeria
O O Yekin, A R Ojo
Scarcity of choice timber species in Nigeria necessitates research into alternative species. Efficient utilisation of alternative species such as Borassus aethiopum requires adequate understanding of their wood properties and within tree variations. However, information on potential of B. aethiopum as alternative to choice timber has not been adequately documented especially in the area of durability. This study was therefore conducted to evaluate variations in the natural durability of B. aethiopum in different ecological zones in Nigeria
Five B. aethiopum trees each from Sudan, Guinea and Derived savanna zones in Nigeria were sampled at the base (10%), middle (50%) and top (90%) of the merchantable length and partitioned into outerwood, centrewood and innerwood along the radial plane. Weight loss (WL) experiment was used to assess natural durability by exposing wood samples to termite (Macrotermis bellicosus) for 12 months in a graveyard experiment. Wood samples were also inoculated with Sclerotium rolfsii (Brown rot fungi) and Pleurotus florida (White rot fungi) for 24 weeks in an accelerated durability test (ADT) using standard procedure. Data were analysed using descriptive statistics and ANOVA at α0.05.
The highest WL of 41.0±0.83% was obtained for innerwood. Brown rot degraded wood by 5.0±0.07%, 26.6±1.2% and 81.9±2.8%, while white rot degraded it by 4.0±0.01%, 19.4±2.2% and 76.9±5.1% in the outerwood, centrewood and innerwood, respectively.
Evidently from this research work, it was observed that termite and fungi will naturally visit the wood of B. aethiopum but the outerwood is resistant to termite and fungi while other parts (centre and inner wood) are susceptible to termite and fungi attack