EARLY EVALUATION OF RACOSPERMA-AURICULIFORME AND RACOSPERMA-MANGIUM PROVENANCE TRIALS ON 4 SITES IN ZAIRE

We examined provenance variation in two Racosperma species (R. auricul iforme and R. mangium) on four test sites in Zaire. Seeds for the two species were obtained from Northern Territory and Queensland of Austra lia, Papua New Guinea, Indonesia, Congo and Zaire. Growth and morpholo gical characters (height, diameter, number of stems, branch angle, ste m straightness, volume and flowering), survival and wood specific grav ity were measured at ages 3, 9, 15 and 21 months. Site effects were si gnificant and significant provenance differences existed in all traits except branch angle. The rank of provenances changed across sites, in dicating significant genotype X environment interactions. Correlations of field growth traits (diameter, height and volume) at different age s were positive but negatively correlated with nursery results. Clinal variation was observed, especially for survival rate. The Racosperma provenances with the greatest volume production were from Papua New Gu inea, They are suited for reforestation programs in Zaire and other tr opical countries sharing similar biogeoclimatic conditions. Additional genetic gains in growth and wood density could be obtained through se lection and breeding of superior individuals from these provenances.