Kernel morphometric characteristics and oil content among Shea tree genotypes in Uganda

Shea tree (Vitellaria paradoxa subsp. nilotica) is an important commercial tree for domestic oil and industrial products of cosmetics, chocolate and other confectionaries traded grown worldwide. We studied seed morphometric characteristics and crude oil content of Shea nuts in Uganda. Five populations, comprising of 16 ethnovarieties, were selected from Eastern, Northern and West Nile Sub-regions of Uganda, based on their attributes as judged by the farmers. Fresh kernel weight ranged from 2 to 18.85 mg per seed. Kernel weight increased with Shea fruit weight (y = 0.1499x + 6.1887, R² = 0.306). Moyo district had the highest oil content (54.37 ± 0.32%); while Amuru district had the lowest oil content (50.5 ± 1.32%). Oil content decreased with increasing kernel size (y = -0.4541x + 57.303, R² = 0.2116) and dry matter content (y = 0.635x - 9.863, R²= 0.011); and varied between ethnovarieties and Shea tree populations, p = 0.003 and P< 0.001, respectively. Tinny seeded (45.7 - 65.49%), Round fruited (45.41 - 65.91%), Dwarf tree (45.19 - 64.19%), Elliptical fruited (45.32 - 64.19%) and Soft pulped (42.16 - 69.77%) ethnovarieties had the highest oil content. Narrow sense heritability (h2) for oil yield was 1.72; while response to selection (R) was 16.48 with genetic gain (Gs) of 2.21%, given 10% top selection intensity

Tree species composition, structure and utilisation in Maruzi Hills Forest Reserve in Uganda

The study investigated the tree species composition, vegetation structure and harvesting pattern to guide management of the Maruzi Hills Forest Reserve. Stratified random sampling was used to site six (100 m × 100 m) permanent sample plots in the woodland, bushland and grassland vegetation types identified in the reserve. Rényi diversity profiles indicated that bushland vegetation had a lower Shannon diversity index (H = 2.054) than grassland (H = 2.38) and woodland vegetation (H = 2.319). Grassland and woodland vegetation also had lower proportions of the dominant species (α∞ = 1.15 and 1.66, respectively) than bushland vegetation (α∞ = 3.25). However, the mean stem density of the woodland, bushland and grassland vegetation was 214 stems ha-1, 191 stems ha-1 and 114 stems ha-1, respectively. Bray-Curtis and Jaccard ecological distance matrices showed that, although the three vegetation types shared some common species, the ecological distances were relatively high suggesting significant species composition variation between the vegetation types, particularly between the bushland and the other vegetation types. The species with the highest proportional abundance in the survey were Combretum molle (23%), Acacia hockii (17.7%), Combretum collinum (16.1%), Grewia mollis (6.5%) and Lannea barteri (6.5%). Diameter size-class distribution of woody perennials and tree stumps indicated higher frequencies of the smaller-diameter size classes. The stump records were indicative of charcoal burning and firewood collection as major causes of tree/shrub harvesting. The Maruzi Hills woodland conservation strategy should consider the differences in species composition between vegetation types if the highest number of species is to be conserved. Keywords: diameter class distribution, species diversity, stump characteristicsSouthern Forests 2010, 72(2): 112–11

Variation in Seedling Germinationand Growth in Five Populations Ofvitellariaparadoxa C.F. Gaertn.subsp. Nilotica: A Threatenedusefulfruit Tree Species in Uganda

We studied seedlings germination and growth performance in an economically and socially important fruit tree species of Vitellaria paradoxaC.F. Gaertn.subsp. nilotica (Kotschy) in Uganda. The study aimed at determining variability in germination of the five shea tree seed lots and seedlings growth performance based on their growth traits. Five populations were considered from four agroecological zones of Uganda and 180 candidates plus trees (16 ethnovarieties) selected as seed trees based on their traits for faster growth and high oil yield. A total of 1204 biological seeds were collected and sown in a general tree nursery at Ngetta Zonal Agricultural Research and Development Institute (NgeZARDI)during the month of June 2018 in a randomized incomplete block design with three replications. Significant variation (χ = 526; p < 0.01) was observed in seedling phenotypic traits within and between populations. Regression equation for height growth and leaf size index were given asy = 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 (19.69 cm)compared to the population average (19.04 cm). Red seeded; thin pulped and hairy fruited shea tree ethnovarieties assumed faster growth than the rest. The phenotypic analysis of shea tree seedlings revealed some fast-growing genotypes from the five studied populations. Thesegenotypes can be selected for faster growth for shea tree breeding in Uganda