Variability in seed- and seedling-related traits of Millettia ferruginea, a potential agroforestry species

Millettia ferruginea (Hochst.) Baker is a potential agroforestry species endemic to Ethiopia. No documented information exists about genetic variation in this species, thus baseline information is needed to initiate improvement program. Here, we quantified variations in seed size, germination and seedling growth at nursery stage based on seeds collected from six sites across the natural range of distribution of the species in Ethiopia. All seed- and seedling-related traits exhibited highly significant differences among seed sources (P < 0.01), and the magnitude of genetic variation was substantially higher (77-99%) than the environmental variation. The genetic advance as percent of the mean was higher for germination capacity (69.4%) and seed weight (31.7%) than for other traits, suggesting that the population means for these traits may be changed considerably by selecting the superior 5% of the genotypes. There were strong phenotypic (r(p) = 0.81) and genotypic (r(g) = 0.89) correlations between seed width and seed weight, so also between seedling height and root collar diameter (r(p) = 0.95 and r(g) = 1.00). In conclusion, the results reveal the existence of substantial genetic variation, which can be utilized to initiate tree improvement program of the species and for gene conservation in seed banks.