Author(s)

Juventine B. Odoi^1,2, Thomas L. Odong², Clement A. Okia^3,4, John Bosco Lamoris Okullo², Moses Okao⁵, Harriet Kabasindi⁶, Alice Mucugi³, Samson Gwali¹

¹National Forestry Resources Research Institute (NaFORRI), National Agricultural Research Organization (NARO), Kampala, Uganda.
²Department of Crop Production, College of Agricultural and Environmental Sciences, Makerere University, Kampala, Uganda.
³World Agroforestry (ICRAF), Nairobi, Kenya.
⁴Muni University, Arua, Uganda.
⁵Ngetta Zonal Agricultural Research and Development Institute (NettaZARDI), Lira, Uganda.
⁶Faculty of Natural Resources and Environmental Sciences, Busitema University, Busia, Uganda.

We studied seed germination and seedling growth performance in an economically and socially important fruit tree species Vitellaria paradoxa C.F. Gaertn. subsp. nilotica (shea tree) in Uganda. The study aimed at determining variations in germination among five shea tree seed provenances and seedling growth performance based on five growth traits (total height, root collar diameter, leaf length, leaf width and leaf petiole length). Five populations were considered from four agroecological zones comprising of 180 candidate “plus” trees. The seed trees consisted of 16 ethnovarieties selected based on their traits for fast growth and high oil yield. A total of 1,204 biological seeds were collected and sown in a tree nursery at Ngetta Zonal Agricultural Research and Development Institute during the month of June 2018 in a randomized incomplete block design with three replications. Significant variation (χ = 708; p < 0.01) was observed in seedling phenotypic traits within and between populations. Regression equation for height growth and leaf size index were given as y = 0.3787 + 12.671x and y = 0.6483 + 15.413x respectively. Root collar diameter was more correlated to leaf size index (0.425) than to height growth (0.30). Clustering of shea tree seedlings based on phenotypic growth traits revealed one aggregated cluster indicating that most of the seedlings from the five populations were similar (Jaccard index 0.92, p < 0.01). However, clustering based on SNP markers revealed three different populations. We recorded higher growth (χ = 708; p < 0.001) in Arua shea population. Red seeded; thin pulped and hairy fruited shea tree ethnovarieties recorded faster growth than the rest. The results reveal useful traits in selection for tree growth and further identified shea tree ethnovarieties that could be selected for fast growth.

Ethnovarieties, Plantlets, Root Collar Diameter, Leaf Size Index, Population, Cluster

Odoi, J. , Odong, T. , Okia, C. , Okullo, J. , Okao, M. , Kabasindi, H. , Mucugi, A. and Gwali, S. (2021) Variation in Seed Germination and Seedling Growth in Five Populations of Vitellaria paradoxa C.F. Gaertn. Subsp. Nilotica in Uganda. Agricultural Sciences, 12, 769-782. doi: 10.4236/as.2021.127050.