The specific environment, in which a tree grows particularly at the stage of germination and early growth, determines the extent to which it attains its potential development. The climatic, edaphic and biotic factors, all influence the expression of hereditary characteristics. The effects of depth of sowing using forest topsoil on germination of Ricinodendron heudelotii seeds, and those of varying the intensity of the climatic factor, light, on the seedlings were determined in this study. Experiments were conducted in a nursery, using soil-filled polyethylene bags where varying sowing depths (5.5, 11, 13.8 and 16.5 cm) were evaluated. Seedlings were grown under light intensity ratios of 1:0.99, 1:1.6, and 1:0.75 lux meters, respectively. The experimental design was a complete randomized design and data collected were subjected to analysis of variance, using LSD for the separation of means at 5% level of probability. Cumulative germination percentages for sowing depths were as follows: 16.5 cm (22%) > 5.5 cm (16%) > 11 cm (14%) > 13. 8 cm (10%) with interactive significant mean differences. Mean value at the depth of 16.5 cm was significantly different from those at the other depths. There was no significant difference among the parameters for early seedling growth under the different light regimes.
Key words: Sowing depth, edaphic, light intensity, Ricinodendron heudelotii germination, early growth.