¹Jimma Agricultural Research Center, P. O. Box 192, Jimma, Ethiopia.

²Institute of Crop Science and Resource Conservation-Plant Nutrition, University of Bonn, Karlrobert-Kreiten-Str.13, D-53115 Bonn, Germany.

*Corresponding author. E-mail: kufataye@yahoo.com. Tel: +251-912 0329 52. Fax: +251-471-11 19 99.

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The study was carried out with the objective to compare the variations in root growth characteristics of wild Coffea arabica populations in Ethiopia. A total of 24 wild coffee trees were used for in-situ root growth measurements under four natural coffee forests, viz., Harenna, Bonga, Birhane-Kontir and Yayu. Analysis of variance was performed to compare the variability among and within wild coffee population in root growth parameters. The results depicted significant variations among the wild coffee populations in the size and length of larger lateral roots (p < 0.01), taproot fresh and dry weights as well as taproot volume (p < 0.05). The populations also exhibited significant differences (p < 0.05) in total root fresh and dry weights. There were also significant site variations in the number of large and fine laterals as well as in the length of medium laterals. The frequency of small laterals varied significantly among sub-sites. In addition, sites significantly differed in the moisture contents of taproot (p < 0.05) and total root growth (p < 0.01). Meanwhile, significantly (p < 0.05) high proportions of coarse laterals were found in Bonga and Berhane-Kontir, whilst the proportions of fine and medium laterals were high in the Yayu and Harenna populations. In addition, the surface plate laterals were significantly (p < 0.01) thick and longest at Harenna and the next longest recorded at Berhane-Kontir. The significantly (p < 0.05) longest fine lateral roots was from the Berhane-Kontir population. Similarly, both lateral root fresh and dry weights were maximum at Berhane-Kontir and lowest at Yayu, intermediate at Herenna and Bonga forests. The results also depicted root variations within sites, largely due to the possible effects of varying intensities of human disturbance on site factors and plant growth response. The extent of variations in root growth also varied across geographical areas, demonstrating the strong link between coffee genetic and climatic factors. Hence, the present findings imply the need to consider root traits in developing coffee technologies and to support sustainable management of natural forest environments.