Variation in seed and germination characteristics among Juniperus procera populations in Ethiopia

Variations in seed and germination characteristics among nine Juniperus procera populations in Ethiopia were evaluated. Bulk seed samples were collected and examined for variations in number of seeds per cone, seed length, width, 1000-seed weight and germination in the laboratory and nursery. In the laboratory, the effect of light conditions on seed germination was tested by incubating the seeds under continuous light or darkness. Significant variations (p < 0.05 for all traits) among J. procera populations were detected for all seed characters: number of seeds per cone, seed length, width and 1000-seed weight. Germination in the laboratory also varied significantly among populations (p = 0.012) as well as light conditions (p = 0.037). The overall germination performance of seeds incubated under continuous light was significantly higher than seeds incubated in darkness. However, seeds from some populations germinated equally well in light and darkness, suggesting that photo-dormancy in juniper seeds varies between populations. Germination of seeds sown on nursery beds was relatively lower than seeds germinated under continuous exposure to light in the laboratory. Among geo-climatic variables, the mean annual rainfall of seed collection sites displayed a significant correlation with number of seeds per cone (r = 0.71; p < 0.05) and seed length (r = 0.73, p < 0.05), and between longitude and rate of germination (r = 0.73, p < 0.05). A significant intercharacter correlation was also found between seed length and seed width (r = 0.78, p < 0.05), and between seed weight and number of seeds per cone (r = 0.91, p < 0.01). It can be concluded that the observed patterns of variation will have an important implication for gene conservation and tree improvement program of the species in the future.