Assessment of farmers' knowledge and perceptions of coffee yield reduction due to weeds and their management in Ethiopia.

The home of Coffea arabica is in Ethiopia, where it has high genetic diversity and suitable growing conditions; unfortunately, the national average yields of coffee remain low due to no technical advancements and diverse, complex biotic and abiotic constraints. Hence, this study was conducted in eight major coffee-growing zones of Ethiopia to assess farmers' knowledge and perceptions of coffee yield reduction due to weeds and the farmers' weed control practices. A purposive and random sampling technique was used to generate primary data from coffee growers (N = 320) using a semi-structured questionnaire. Quantitative data were analyzed using a three-stage nested design, and the dependent and independent variables data were subjected to canonical correlation analysis. This study revealed variation in coffee yield (t ha-1) among the assessed areas based on farmers' knowledge of estimating coffee yield. The average yield level ha-1 was very low (0.37 t ha-1) and different among the surveyed areas. The average coffee yield gap as compared to the current national level (0.64 t ha-1) was observed to be 42%, and this low yield was highly correlated with weed infestation (r = 0.879) and type of weeds r = -0.528). This investigation indicated a single factor or association of different factors contributing to the low yield level of coffee in the study areas. Thus, it is concluded that predictor variables accounting for the low yield levels need to be considered when planning future strategies to attain the yield potential of C. arabica in Ethiopia.

Evaluation of the herbicidal potential of some fungal species against Bidens pilosa, the coffee farming weeds.

Weeds are the most productive limiting factor, especially in organic farming systems where the uses of synthetic herbicides are not allowed due to their negative impacts. Hence, synthetic herbicides need to be replaced with biological herbicides for weed management. Thus, the present study was designed to evaluate the herbicidal activity of conidia suspensions from Aspergillus niger, Trichoderma asperlium, Trichoderma atroviride, Trichoderma hamatum, Trichoderma harzanium, Trichoderma longibrachatum and Trichoderma viride against Bidens pilosa weed via a series of laboratory and lath-house conditions that laid out in a CRD and RCBD, respectively, with three replications for each bioassay. The results revealed that all fungi, except T. longibrachatum, had significantly reduced seed germination as well as early growth of the target weed compared to the untreated control. The inhibitory effects were measured to be varied among the types of conidia suspensions of fungal species and their level of concentration. The highest rate of inhibition was observed for conidia suspension from A. niger which suppressed with the maximum seed germination inhibitory level (65%) over control. Likewise, the plumule and radicle growth length of the target weed also significantly inhibited by the tested fungi (ranging from 10 to 85% and 34 to 97%) compared to the control, respectively. Based on their efficacy in the laboratory bioassay, the herbicidal potential of selected fungi was further evaluated in pot experiments. In contrarily to laboratory observations, the effect of different fungal conidia suspensions on various growth parameters of the targeted weed was insignificant in the lath-house experiments. In conclusion, the application of A. niger displayed some potential green light to be investigated as a biocontrol agent with promising retarding in the germination and early growth of B. pilosa. Hence, we recommend further investigation of those fungi under field conditions on different coffee weed species.

Antidiabetic activity and phytochemical screening of extracts of the leaves of Ajuga remota Benth on alloxan-induced diabetic mice.

BACKGROUND: Ajuga remota Benth is traditionally used in Ethiopia for the management of diabetes mellitus. Since this claim has not been investigated scientifically, the aim of this study was to evaluate the antidiabetic effect and phytochemical screening of the aqueous and 70% ethanol extracts on alloxan-induced diabetic mice. METHODS: After acute toxicity test, the Swiss albino mice were induced with alloxan to get experimental diabetes animals. The fasting mean blood glucose level before and after treatment for two weeks in normal, diabetic untreated and diabetic mice treated with aqueous and 70% ethanol extracts were performed. Data were statistically evaluated by using Statistical Package for the Social Sciences software version 20. P-value <0.05 was considered statistically significant. RESULTS: The medium lethal doses (LD50) of both extracts were higher than 5000 mg/kg, indicating the extracts are not toxic under the observable condition. Aqueous extracts of A.remota (300 mg/kg and 500 mg/kg body weight) reduced elevated blood glucose levels by 27.83 ± 2.96% and 38.98 ± 0.67% (P < 0.0001), respectively while the 70% ethanol extract caused a reduction of 27.94 ± 1.92% (300 mg/kg) & 28.26 ± 1.82% (500 mg/kg). Treatment with the antidiabetic drug, Glibenclamide (10 mg/kg body weight) lowered blood glucose level by 51.06% (p < 0.05). Phytochemical screening of both extracts indicated the presence of phenolic compounds, flavonoids, saponins, tannins, and steroids, which might contribute to the antidiabetic activity. The extracts, however, did not contain alkaloids and anthraquinones. CONCLUSION: The aqueous extract (500 mg/kg) showed the highest percentage reduction in blood glucose levels and the ability of A. remota extracts in reducing blood glucose levels presumably due to the presence of antioxidant constituents such as flavonoids. The effect of the extract supported the traditional claim of the plant.