Coffee production in Uganda is done on small-scale farms containing a very significant tree component. However, there is little information on how tree species abundance, richness and diversity change in coffee farms as distance from forest changes. The main objectives of this study, therefore, were to assess (a) abundance and (b) diversity of tree species in the coffee production systems in proximity to disturbed and undisturbed forest around Mabira forest, one of Uganda's Robusta coffee-growing areas. Seventy-nine 0.1 ha plots were established in nine villages close to undisturbed and disturbed forest, and over 5 km from the forest. A total of 875 trees belonging to 63 species were recorded. There was significant similarity in species composition among the three study sites (analysis of similarity R = 0.09, p < 0.01; analysis of variance: F3,12 = 0.353, p = 0.79). Non-metric dimensional scaling supported these findings (stress value = 0.224 at k = 2) and showed that tree species composition in the three proximity categories was very similar. These results demonstrate that tree species composition and diversity is similar in coffee farms regardless of their distance from the nearest natural forest and forest exploitation history. (Résumé d'auteur

Jatropha curcas Linn has been identified worldwide as one of the sources of biodiesel. Biodiesel has energy properties close to fossil diesel and can be a potential energy alternative. However, these properties may vary based on soils, plant genetics and agro-climatic conditions in a given geographical location. Several studies on biodiesel production under such conditions have been done elsewhere, but few have been done on J. curcas oil in Uganda. This study analysed the physicochemical properties of J. curcas L. oil for biodiesel production in Nebbi and Mukono districts using American Standards and Testing Methods (ASTM D6751) and European Standards (EN 14214). J. curcas seed kernel contained 51% w/w and 48% w/w of oil with high levels of Free Fatty Acids (1.52% and 1.93%) and acid values (35 and 36 mg KOH/g) for Nebbi and Mukono, respectively; the difference was significant (p ≤ 0.05). Generally, the quality and quantity of the oil from Nebbi were better than those of Mukono, based on the biodiesel standard values. Nevertheless, kinematic viscosity, acidity, potassium and phosphorus content values were found abnormally high (31.46 -33.23 mm 2 /s, 35.23 -36.66 mg KOH/g, 16.50 -20.52 mg/100g and 16.13 -26.02 mg/kg, respectively) for both regions as compared to the standard values (3.5 -5.0 mm 2 /s, 2 mg KOH/g, <5 mg/100g and <10 mg/kg, respectively) of biodiesel for diesel engine. Such properties are very important for engine fuels and if not considered well, may affect engine performance negatively. Therefore adequate treatment of the oil by degumming, etherification and transesterification before use in a diesel engine could avert this difficulty.

Local knowledge on maturity indicators is important in determining optimal time of harvesting fruits and vegetables. These farm products are increasingly becoming a valuable source of livelihood for many rural families through household consumption and trade. Unfortunately, there is a dearth of literature on the integration of local knowledge and practices in improving maturity assessment techniques with the view of promoting optimal harvesting and consumer acceptability of fruits and vegetables in Uganda. A study was undertaken between April and September 2014 to prioritize viable fruits and vegetables, ascertain socioeconomic characteristics influencing maturity assessments, assess local knowledge on maturity indicators and document maturity assessment challenges faced by fruit and vegetable farmers, transporters and traders in Kampala, Rubirizi and Sheema districts. A total of 102 respondents were interviewed as corroborative measure to field visits and focused group discussions involving 27 participants. The findings indicate that passion fruit, watermelon and pineapple were the most preferred fruits while tomato, cabbage and eggplant were highly ranked among vegetables. About 99% of the respondents were knowledgeable about fruit and vegetable maturity indicators. The knowledge of maturity indicators appears to be associated with gender, age, education level, marital status, household size and occupation of the respondents. The maturity indicators used include colour for pineapple (100%, N=102), passion fruit (100%), tomato (90%) and watermelon (11%). Size is used as a maturity indicator for pumpkin, eggplant and cabbage by 100%, 85% and 50% of the respondents, respectively. Respondents felt that the maturity indicators they use are inaccurate (53%) and are influenced by pest and disease infestation (40%), weather (5.8%) and soil (1.4%) conditions. To leverage adoption, participatory design and development of noninvasive maturity assessment tools is, therefore, recommended.