SELECTION OF PLUS TREES FOR GENETICALLY IMPROVED TEAK VARIETIES PRODUCED IN BENIN AND TOGO

Abstract

The aim of this study is to select “Plus Trees” based on dendrometric character- istics and wood properties in teak plan- tations in Benin and Togo. For this pur- pose, growth performance was assessed in 569 trees in 5 forests in Togo and 90 trees in 3 forests in Benin, based on diameter at breast height, total height and bole height measurements. Wood properties – density, percentage of heart- wood and colour – were also measured for the final selection of Plus trees. Heart- wood natural durability, fibre saturation point, modulus of elasticity and shrink- age were assessed against previous near infrared spectroscopy models. The results showed that in Togo, inter-tree variability in the forests was relatively high for Annual Height (0.81 ± 0.27 m) and Annual Circumference Increments (2.95 ± 1.02 cm) and for bole heights (10.64 ± 3.51m). In Benin, while the dendrometric performance of the trees did not vary significantly between the forests, the coefficient of variation val- ues were higher (40%) for bole heights (10.99 ± 3.80 m) in Koto forest. The final multi-criteria selection including wood properties showed that the Avetonou and Tchorogo tree populations in Togo make up a homogenous group with the highest values for wood density and heartwood percentage. The trees in Haho-Baloe and Eto forests had lower natural durability and modulus of elasticity, a lower per- centage of heartwood and lower wood density. In Benin, the Agrimey forest trees had a higher wood density but the 3 forests were similar in terms of fibre saturation point, natural durability and shrinkage. Based on the variability of dendrometric performance and wood quality of the candidate trees, we were able to select 33 Plus trees