Evaluation of the adaptability and response of indigenous trees to assisted rehabilitation on the degraded hillsides of Kuriftu Lake Catchment(Debre Zeit,Ethiopia)

Removal of trees and shrubs from hillsides exposes a site to erosion that threatens soil aggregation and stability. The present study aimed at evaluating the performance of five indigenous tree species in rehabilitation of degraded hillsides of Kuriftu Lake Catchment and the role of water harvesting structures. Adaptability varied by tree species and water harvesting structures significantly augmented seedling es-tablishment for some tree species. Height ofAcacia abyssinicaplanted on steeper slopes （18%-27%） without infiltration pits was lower than for conspecifics planted with infiltration pits.Dodonaea angustifolia wasproved to be best adapted to the siteand showed no need for water harvesting regardless of planting position across the degraded hillside. Planting ofAcacia seyalshould be restricted to gentler slopes （0-17%） with infiltration pits： tree height declined significantly on steep slopes without infiltration pits.Olea africanaperformed better on gentle slopes with pits but also grew well on steeper slopes with pits.Euclea schim-periwasproved to be least effective of the species evaluated in this study.

Plant community and ecological analysis of woodland vegetation in Metema Area,Amhara National Regional State,Northwestern Ethiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia to determine plant community types and species distribution patterns and their relationships with environmental variables, including altitude, pH, cation exchange capacity, electrical conductivity （EC）, and moisture. We used a selective approach with a systematic sampling design. A total of 74 quadrats, each 25m × 25m at intervals of 150-200 m were sampled along the established transect lines. For herbaceous vegetation and soil data collection, five subquadrats each lm x lm were established at the four corners and the center of each quadrat. Three community types were identified using TWINSPAN analysis. All three community types showed high diversity （Shannon-Weiner index）, the highest in community type II at 3.55. The highest similarity coefficient was 0.49 （49%） between community types II and III, reflecting 0.51 （51%） dissimilarity in their species richness. The canonical correspondence ordination diagram revealed that the distribution pattern of community type I was explained by moisture while that of community types III and II was explained by EC and altitude and moisture, respectively. Altitude was the most statistically significant environmental variable, followed by moisture and EC in determining the total variation in species composition and distribution patterns while pH and cation exchange capacity were non significant. In conclusion, we recommend that any intervention should take into account these three discrete community types and their environmental settings to make the intervention more successful.

Floristic diversity, regeneration status, and vegetation structure of woodlands in Metema Area, Amhara National Regional State, North-western Ethiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, re- generation status, and population structure by a selective approach with a systematic sampling design. A total of 74 quadrats （each for 25 m x 25 m, spaced at intervals of 150--200 m） were sampled along established tran- sect lines following the homogeneity of the vegetation. Vegetation data including cover-abundance, height, diameter at breast height （DBH）, and numbers of seedlings and saplings of woody species were analyzed using Excel spreadsheet, Shannon Weiner diversity index, and PAST version 1.62. A total of 87 vascular plant species of 74 genera and 36 families were recorded. The dominant family was Fabaceae represented by 16 （18.39 %） species of 13 genera. Shannon Weiner diversity and evenness were 3.67 and 0.82, respectively, which showed that the area was en- dowed with rich floral diversity evenly distributed. The vegetation structure, as quantified by cumulative diameter class frequency distribution, plotted as an interrupted inverted-J- shape pattern with a sharp decrease in the 2nd diameter class. This indicated poor vegetation structure. The diameter classes frequency distributions of selected species plotted in four general patterns i.e., interrupted Inverted-J-shape, J-shape, Bell-shape and Irregular-shape. In conclusion, although the area showed high floral diversity and evenness, woody species including Sterculea setigera, Boswellia papyrifera, and Pterocarpus lucens showed lowest recruitment of seedlings and saplings.

Management of <i>Helicoverpa armigera</i>(Lepidoptera: Noctuidae) by Nutritional Indices and Botanical Extracts of <i>Millettia ferruginea</i>and <i>Azadirachta indica</i>

The development of hosts that are resistant and evaluation of botanical extracts to H. armigera Hübner (Lepidoptera: Noctuidae) is crucial for sustainable management, yet very limited in Ethiopia. Therefore, this study was done to identify alternative methods to insecticide control through host consumption study and botanical extracts. The performance of third-fifth larval stages of H. armigera on three host plant varieties including chickpea, tomato and faba bean and botanical extracts against the third larval instars and oviposition deterrence was studied under laboratory condition (22°C ± 2°C, 55% ± 5% RH, 12:12 L: D photoperiod). Significant differences were found in the efficiency of conversion of ingested food (ECI%) (F = 80.06;df = 6, 2;p H. armigera reared on the three host plant varieties of the whole larval instars. The minimum relative consumption rate (RCR) (11.271 ± 0.328) and maximum approximate digestibility (AD) (177.9 ± 1.928) values of the whole larval instars were on Dagaga and Koshari, respectively. The values of relative growth rate (RGR), ECI% and ECD% of the whole larval instars were highest on chickpea varieties and lowest on tomato Koshari. Among chickpea varieties, Habru was relatively resistant to larval instars of H. armigera. Botanical extracts at 50% neem oil (NO), 5% birbira seed extract (BSE) and 5% neem seed extract (NSE) (18.4%) resulted superior in larval mortality however, statistically not different. At both 5% and 2.5% concentration level of botanical extracts the minimum larval mortality was recorded from neem leaf extract (NLE). Maximum numbers of eggs were laid on control treatments and the minimum eggs were on 5% BSE. The deterrent effect of 50% neem oil was stronger (ODI = 17.66%) than that of 5% BSE (ODI = 14%) which is statistically similar value with 5% NSE (ODI = 13%). In conclusion, the result indicated that use of Habru chickpea variety with 50% NO was very effective in controlling both the larvae and deterring the adults of H. armigera from egg lying. These measures could be important in the wider managements of H. armigera by integrating host resistance and botanical extracts.

Grain yield stability analysis using parametric and nonparametric statistics in oat(Avena sativa L.)genotypes in Ethiopia

Background:The performance of oat genotypes differs across environments due to variations in biotic and abiotic factors.Thus,evaluation of oat genotypes across diverse environments is very important to identify superior and stable genotypes for yield improvement.Methods:The study aimed to assess the interaction(genotype-by-environment interaction;GEI)effect and determine the stability of grain yield in oat(Avena sativa L.)genotypes in Ethiopia using parametric and nonparametric stability statistics.Twenty-four oat genotypes were evaluated in nine environments using a randomized complete block design replicated three times.Results:The pooled analysis of the variance of grain yield showed significant variations among genotypes,environments,and their interaction effects.Significant GEI revealed the rank order change of genotypes across environments.The environment main effect captured 44.62%of the total grain yield variance,while genotype and GEI effects explained 28.84%and 26.54%of the total grain yield variance,respectively.The grain yield stability was assessed based on 12 parametric and two nonparametric stability statistics.The results indicated that genotypes with superior grain yield-showed stable performance on the basis of the stability parameters of the genotypic superiority index(P_(i)),the Perkins and Jinks adjusted linear regression coefficient(B_(i)),and the yield stability index(YSI),indicating that selection using these stability parameters would be efficient for grain yield enhancement in oat genotypes.Spearman's rank correlation coefficients also showed that the stability parameters of P_(i),B_(i),and YSI had a significant positive association with grain yield.However,grain yield had an inverse correlation with the stability parameters of standard deviation,deviation from regression (S_(di)^(2)),the Hernandez desirability index(D_(ji)),Wricke ecovalence(W_(i)),the Shukla stability variance(σ_(i)^(2)),the AMMI stability value(ASV),and environmental variance (S_(i)^((2))),indicating that oat genotype selection using these stability parameters would not be efficient for yield enhancement because these stability parameters favor low-yielding genotypes more,compared to high-yielding ones.Conclusions:Therefore,G5,G8,G11,G12,G14,G16,G17,G19,and G22 genotypes were adaptable in all nine environments based on stability parameters of Pi,Bi,and YSI,and selection of these superior genotypes would improve grain yield in oat genotypes.However,the validity of this result should be confirmed by repeating the experiment in the same environments over two or more years.

Symbiotic performance,shoot biomass and water-use efficiency of three groundnut(Arachis hypogaea L.)genotypes in response to phosphorus supply under field conditions in Ethiopia

Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism,respiration and photosynthesis and its supply at low levels can affect legume nodulation,N2 fixation,and C assimilation.A twoyear field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth,symbiotic N2 nutrition,grain yield and water-use efficiency of three groundnut genotypes.Supplying P to the genotypes significantly increased their shoot biomass,symbiotic performance,grain yield,and C accumulation.There was,however,no effect on shootδ13C values in either year.Compared to the zero-P control,supplying 40 kg$ha–1 P markedly increased shoot biomass by 77%and 66%in 2012 and 2013,respectively.In both years,groundnut grain yields were much higher at 20 and 30 kg$ha–1 P.Phosphorus supply markedly reduced shootδ15N values and increased the%Ndfa and amount of Nfixed,indicating the direct involvement of P in promoting N2 fixation in nodulated groundnut.The three genotypes differed significantly inδ15N,%Ndfa,N-fixed,grain yield,C concentration,andδ13C.The phosphorusgenotype interaction was also significant for shoot DM,N content,N-fixed and soil N uptake.