Gezahegn Berecha

Genetic variation and risks of introgression in the wild Coffea arabica gene pool in south-western Ethiopian montane rainforests

The montane rainforests of SW Ethiopia are the primary centre of diversity of Coffea arabica and the origin of all Arabica coffee cultivated worldwide. This wild gene pool is potentially threatened by forest fragmentation and degradation, and by introgressive hybridization with locally improved coffee varieties. We genotyped 703 coffee shrubs from unmanaged and managed coffee populations, using 24 microsatellite loci. Additionally, we genotyped 90 individuals representing 23 Ethiopian cultivars resistant to coffee berry disease (CBD). We determined population genetic diversity, genetic structure, and admixture of cultivar alleles in the in situ gene pool. We found strong genetic differentiation between managed and unmanaged coffee populations, but without significant differences in within‐population genetic diversity. The widespread planting of coffee seedlings including CBD‐resistant cultivars most likely offsets losses of genetic variation attributable to genetic drift and inbreeding. Mixing cultivars with original coffee genotypes, however, leaves ample opportunity for hybridization and replacement of the original coffee gene pool, which already shows signs of admixture. In situ conservation of the wild gene pool of C. arabica must therefore focus on limiting coffee production in the remaining wild populations, as intensification threatens the genetic integrity of the gene pool by exposing wild genotypes to cultivars.

Protecting coffee from intensification.

![Figure][1] Coffee beans PHOTO: TONY OQUIAS/[ISTOCKPHOTO.COM][2] Sustainable agricultural intensification is one approach to meet food security and biodiversity conservation goals simultaneously ([ 1 ][3], [ 2 ][4]). The yield increases required to achieve these goals can be facilitated by

Fragmentation and management of Ethiopian moist evergreen forest drive compositional shifts of insect communities visiting wild Arabica coffee flowers.

Coffea arabica is an indigenous understorey shrub of the moist evergreen Afromontane forest of SW Ethiopia. Coffee cultivation here occurs under different forest management intensities, ranging from almost no intervention in the ‘forest coffee’ system to far-reaching interventions that include the removal of competing shrubs and selective thinning of the upper canopy in the ‘semi-forest coffee’ system. We investigated whether increasing forest management intensity and fragmentation result in impacts upon potential coffee pollination services through examining shifts in insect communities that visit coffee flowers. Overall, we netted 2,976 insect individuals on C. arabica flowers, belonging to sixteen taxonomic groups, comprising 10 insect orders. Taxonomic richness of the flower-visiting insects significantly decreased and pollinator community changed with increasing forest management intensity and fragmentation. The relative abundance of honey bees significantly increased with increasing forest management intensity and fragmentation, likely resulting from the introduction of bee hives in the most intensively managed forests. The impoverishment of the insect communities through increased forest management intensity and fragmentation potentially decreases the resilience of the coffee production system as pollination increasingly relies on honey bees alone. This may negatively affect coffee productivity in the long term as global pollination services by managed honey bees are expected to decline under current climate change scenarios. Coffee agroforestry management practices should urgently integrate pollinator conservation measures.

Distribution and Importance of Maize Grey Leaf Spot Cercospora zeaemaydis(Tehon and Daniels) in South and Southwest Ethiopia

Maize (Zea mays L.) is one of the most important cereal crops used in the human diet in large parts of the world as well as in Ethiopia and its production are limited by diseases such as grey leaf spot caused by a fungus Cercospora zeae-maydis. Currently grey leaf spot has become the most important threat to maize production in maize belt areas of Ethiopia causing significant yield loss. The objective of this study was therefore, to assess the distribution and importance of maize grey leaf spot in south and southwest Ethiopia. The field assessments were conducted during the year of 2014 cropping seasons by sampling 110 farmer fields in 11 districts selected from two zones of Oromia region and two zones of Southern Nation, Nationalities and People region (SNNPR). The result revealed that the disease occurs in the entire assessed districts having different agro-ecological zones. Maize grey leaf spot was prevalent in all surveyed farms of south and southwest Ethiopia, 74% of maize fields were infected by grey leaf spot. However, the mean incidence and severity of grey leaf spot on maize was significantly varied from district to district. The highest grey leaf spot incidence (71.2%) and severity (46.2%) was recorded in Boricha district, while Damote Gale had the lowest mean incidence (51.8) and severity (33.5%). Among the surveyed four zones in two regions, the highest incidence was found in Sidama (65.6%) and Illubabore (63.1%) followed by Jimma (62.5%) and Wolaita (57.6%). The highest mean severity of maize grey leaf spot was observed in Sidama (44.5%) followed by Illubabore (43.7%) and Jimma (42.63%) while the lowest severity was recorded in Wolaita (36.4%) zone. The disease was more severe in intermediate/humid areas with intermediate annual rainfall. The current study revealed maize grey leaf spot pressure in maize farms of south and southwest Ethiopia and the need to design an efficient, inexpensive and sustainable management approaches against the pests.

The importance of avocado (Persea americana Mill.) fruits anthracnose and factors influencing the disease in Mana district, south-western Ethiopia

Abstract Anthracnose disease surveys were conducted in 25 farmers’ orchards, wholesaler and retailer shops in south-west Ethiopia. In addition, harvesting and postharvest practices, and storage conditions influencing disease development were studied with observation and questionnaire. The assessment results indicated significant variation among farmers’ orchards with the highest incidence (84.0 ± 16.7%) and severity index (26.0 ± 5.4%). Anthracnose damage of fruit was higher at retailers (76.7 ± 20.8%) than in the wholesalers shop (56.7 ± 32.5%). The total number of isolates identified was 249 and Colletotrichum gloeosporioides was the predominant pathogen proved by pathogenecity test. Among the major factors, harvesting avocado fruits with children (88%) and climbing on the tree (72%) resulted in fruit dropping that caused substantial injury and bruise. Generally, anthracnose caused by C. gloeosporioides of avocado fruit was prevalent in producer orchards that aggravated by traditional harvest and postharvest practices coupled to inadequate transportation and storage facilities at wholesaler and retailer shops with subsequent decay and loss of avocado fruits.

Views from two mountains: exploring climate change impacts on traditional farming communities of Eastern Africa highlands through participatory scenarios

African mountains are characterized by high levels of biodiversity and provide ecosystem services to millions of people. Due to steep environmental gradients, growing human populations and geographical isolation, these coupled socio-ecological systems are highly vulnerable to climate change impacts. The capacity of local stakeholders to anticipate future changes and to assess their potential impacts is paramount for enhancing adaptation and resilience. Here we apply a participatory scenario development framework in two parts of the Eastern Afromontane Biodiversity Hotspot: Taita Hills in Kenya and Jimma rural area in Ethiopia. In each area, we facilitated local stakeholders in envisioning adaptation scenarios under projected climate changes by mid-21st century, and assessed the potential impacts of these pathways on land use and land cover. In the Taita Hills, under a business-as-usual scenario, human population and activities concentrate at high elevation, triggering cascade effects on remnant forest cover, biodiversity and ecosystem services. Alternative adaptation scenarios envisage reforestation associated with either improved agricultural practices or ecosystem restoration. In the Jimma area, rising temperatures are expected to disrupt traditional coffee production under a business-as-usual scenario, resulting in the loss of coffee-forest canopies and reduction of forest-dependent biodiversity. Alternative adaptation scenarios envisage either expansion of commercial coffee plantations or expansion of agroforestry, including traditional coffee farming. In the both Taita and Jimma, adaptation pathways present trade-offs between provisioning, supporting and regulating services, and between livelihoods and biodiversity conservation. Our findings encourage the use of multidisciplinary, bottom-up approaches for developing locally tailored, climate-smart and sustainable adaptation pathways.

Impacts of termites on selected soil physicochemical characteristics in the highlands of Southwest Ethiopia

ABSTRACT Termites are reported to improve soil physicochemical properties thereby enhance soil fertility of their mound and foraging areas. Empirical study pertaining to these effects is missing in Southwest Ethiopia. For this study, soil samples affected by termite activities were collected at 1 m interval within 0–3 m distance from the base of six termite mounds on gently sloping and sloping land and analyzed for physicochemical parameters. The result of the analysis depicted that soil bulk density (1.38–1.15 g cm−3) and moisture content (21.1–9.9%) decreased with increased distance from the mound base. While clay content decreased with increased distance from the mound base from72.0% to 45.5%, sand and silt contents increased from 8.0% to 21.3% and 19.3% to 28.5%, respectively. PH (6.23), organic carbon (3.85%), total nitrogen (0.4%), cation exchange capacity CEC (30.43 cmol kg−1), exchangeable Ca (13.73 cmol kg−1), Mg (3.15 cmol kg−1), and PBS (56.8%) were higher on termite mounds. While, electrical conductivity (0.03 dS m−1–0.06 dS m−1), exchangeable K (0.52–0.93 cmol kg−1) and Na (0.02–0.03 cmol kg−1) showed increasing trend with the distance from the mound base. Our results indicated that termite mounds are important sinks of organic matter and mineral nutrients, and hence contribute to the enhancement of soil fertility. Thus, for subsistent farmers the uses of termite mounds as a fertilizer present an opportunity to improve agricultural production.

Inhibitory effects of some invasive alien species leaf extracts against tomato (Lycopersicon esculentum Mill.) bacterial wilt (Ralstonia solanacearum)

The inhibitory activity of selected invasive alien species leaf extracts against tomato bacterial wilt was studied in vitro and greenhouse. In vitro inhibitory activity was undertaken in a disc diffusion sensitivity test. Furthermore, aqueous extracts of Eichhorina crassipes, Mimosa diplotricha and Lantana camara and methanolic extract of Prosopis juliflora which showed better inhibitory effect in vitro were evaluated against R. solanacearum in greenhouse on tomato. The plant extracts were applied and evaluated at three different times of application (at the time of inoculation; two days before pathogen inoculation; and two days after pathogen inoculation). The result showed that most of the treatment combinations significantly reduce disease incidence and area under disease progress curve and increase biomass of tomato plants, but the effectiveness of tested plant species depends on the type of plant species and application time. The application of plant extracts at the time of pathogen inoculation resulted in highest reduction of disease development on tomato plants. Aqueous extract of E. crassipes was found to be the most effective plant extract in disease suppression and increase above-ground biomass compared to inoculated control. The study revealed that the tested plant species have a potential of inhibiting the development of bacterial wilt on tomato.