Coffea arabica is native to the Afromontane forests of southwestern Ethiopia, the leading African country in Arabica coffee production. The intensity of coffee leaf rust (CLR), a fungal disease of growing concern to coffee farmers, was assessed in eight coffee berry disease-resistant C. arabica varieties planted at three different altitudes. Disease variables assessed were CLR prevalence (percent of infected plants), incidence (percent rusted leaves) and severity (percent leaf area affected) at four times within a year (Nov, Jan, Apr and Jun). The intensity of CLR epidemics was highest at the lowland and lowest at the highland location. We hypothesize that inoculum may be limited by cooling conditions that negatively affects fungal sporulation. CLR intensity was highest at harvest time (Nov) and decreased during the following dry season, reaching zero values in Apr and Jun. All coffee varieties were similarly susceptible to CLR. Our data suggest that more efforts should be employed by breeders to develop CLR-resistant coffee varieties, and that shifting cultivation from lower to higher altitudes may contribute to achieve to higher yields due to lower impact of CLR epidemics.

Purpose In this study, the composting and co-composting potential of coffee husk and pulp with source-separated municipal solid waste (SSMSW) was investigated. Methods Coffee husk and pulp were mixed independently with SSMSW in different proportions (0, 33, 50 and 100%), and composted in triplicates with a total of 24 composting piles for 3 months. From each compost type, different physicochemical parameters were analyzed. In addition, the seed germination, growth and fresh head weight yield of each compost type were investigated on each matured compost type using cabbage seed (Brassica oleracea). Results The results indicate that the two coffee by-products can be composted alone or co-composted with SSMSW yielding very mature and stable compost. The results indicated that the addition of 1/4th of local soil (wt/wt) on C8 compost type yields the optimum fresh head weight of the cabbage among all field experiments. In addition, when C8 compost type is mixed with local soil in 3:1 ratio, it could yield an optimum fresh head weight of the cabbage (572 ± 10 g/kg of compost). This could be due to the relatively higher concentration of total nitrogen in the C8 compost sample. Conclusions Generally, the final compost can be served for unrestricted type of agricultural purposes. Thus, co-composing of coffee husk and pulp with SSMSW can alleviate the multidimensional problems of rural and urban dwellers.

Lack of suitable varieties that exhibit stable yield performances across wide ranges of environments is the major factor among several production constraints contributing to low productivity of Arabica coffee in Ethiopia. Eleven advanced Limmu coffee genotypes were evaluated in eight environments (four locations over two years) to determine the existence of GEI and yield stability performances. The experiment was laid out in a randomized complete block design of two replications under all locations. Combined analysis of variance showed a highly significant effect of genotype by environment interaction indicating the differential yield response of genotypes across different environments. The major proportion of the variation explained by environments was 42.74% of the total variation. Nevertheless, the contribution of the genotypes to the total variance was much smaller than the environments, and the genotype by environment interaction. Different stability models such as additive main effect and multiplicative interaction (AMMI), AMMI stability value, cultivar superiority index and yield stability index were used for stability analysis. The first two Interaction Principal Component Axis (IPCAs) of AMMI exhibited a highly significant effect and cumulatively contributed about 63.21% of the total interaction sum of squares. Two high yielding genotypes, namely (L52/2001) and (L55/2001), on average, showed stable performance across environments. On the other hand, the study also illustrated the presence of location specific high yielding coffee genotype such as L56/2001. Regarding the test environments, Gera 2015/16 (E5) is considered as a more stable site over the rest environments, while Agaro 2015/16 (E7) was considered to be the most interactive environment. Based on the result of the study, coffee breeders or farmers would be recommended for wise selecting either for location specific or wider adaptable coffee genotypes leading to substantial yield increase under Limmu coffee growing areas.

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