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Articles by Fikre Lemessa
Total Records ( 10 ) for Fikre Lemessa
  Gezahegn Berecha , Fikre Lemessa and Mulatu Wakjira
  The current study was designed to evaluate (1) the feasibility of replacing commercial growing media with the different rates (0, 10, 50%) of coffee pulp compost on the height and above ground biomass of tomato in greenhouse bioassay and (2) the effect of top soil amendment with different rates (1, 5, 10% v/v) of coffee pulp composted with grass (CPCG) on the plant biomass of tomato in lath-house. Our results demonstrated that substitution of pro-mix by 10% coffee pulp compost significantly increased aerial biomass, seedling height and number of nodes per plant. Substitution of pro-mix with 10 and 50% coffee pulp compost increased seedling height by 20 and 4%, respectively, compared to pure pro-mix media. Unamended peat moss and peat moss substituted with lower rate (10%) of compost gave the lowest result in all response variables assessed. Top soil amended with 10% CPCG gave remarkably higher root fresh and dry weight and AGFW per pot compared with unamended top soil and top soil amended with 1% CPCG. In conclusion, substitution of Pro-mix media with coffee pulp compost up to 50% and amendment of top soil with 5 and 10% CPCG were found to be a good option for greenhouse/nursery tomato seedling production and field production of tomato, respectively. Furthermore, the possibility of managing coffee byproducts by utilization is demonstrated. However, the effects of substituting commercial growing media with different rates of coffee pulp compost on other commercially important crops worth investigation.
  Amsalu Abera , Fikre Lemessa and Diriba Muleta
  This study was carried out with the objective of evaluating the antifungal potential of aqueous and ethanol extracts of eight different plant species in vitro and in vivo against Colletotrichum kahawae in completely randomized design with three replications. The extracts were from Hagenia abyssinica, Allium sativum, Phytolacca dodcandera, Croton macrostachyus, Maesa lanceolata, Eucalyptus globules, Eucalyptus citriodera and Lippia adoensis. Subsequently, two most effective plant extracts were tested in vivo against the disease on detached green coffee berries and seedling applying the extracts at 3 different times of application (at the time of inoculation and 48 h before and after inoculation) on the pathogen. The study indicated that the inhibitory effect of the extracts depended on the type of plant species used, method of extraction and time of application of the extracts. Generally, A. sativum and C. macrostachyus aqueous and ethanol extracts were the most effective plants that significantly reduced radial growth of the pathogen compared to the control. A. sativum reduced radial growth of the pathogen in ethanol and aqueous extracts by 83 and 100%, respectively and C. macrostchyus by 68 and 88%, respectively. Furthermore, A. sativum extracts consistently reduced disease severity on detached green berries and seedling in greenhouse at all times of application. Nevertheless, the efficacy of C. macrostachyus on detached green berries and seedlings was inconsistent and variable based on method of extraction and time of application of the extracts. The study indicated the possible use of extracts of A. sativum as an alternative means of CBD (coffee berry disease) management but further study at field conditions should be carried out to verify the result.
  Negesu Debere , Fikre Lemessa , Kaba Urgessa and Gezahegn Berecha
  A study was conducted to determine the effect of combined application of inorganic nitrogen and organic phosphorus fertilizers on growth of young tea plant (Camellia sinensis var. assamica). The field experiment was conducted in Gera district in Southwest (SW) Ethiopia during 2010/2011 and 2011/2012 cropping seasons. We used two fertilizers “Orga” and urea as sources of phosphorus and nitrogen, respectively. We tested four rates of nitrogen (75, 150, 225 and 300 kg N ha-1) combined with a constant rate of phosphorus (30 kg P ha-1) and one unfertilized control treatment. The experiment was laid down in a randomized complete block design with three replications. The results showed that combined application of inorganic nitrogen (urea) and organic P (Orga) significantly (p<0.01) enhanced plant height, number of leaves per plant, number of branches per plant, root length, leaf fresh and dry weight and root fresh and dry weight. Among the tested rates, combined application of 150 kg ha-1 N and 30 kg ha-1 P increased leaf number, plant height and branch number per plant by 164.3, 68.8 and 83.4%, respectively compared to control treatment. In conclusion, the use of inorganic nitrogen (urea) fertilizer at 150 kg N ha-1 combined with 30 kg P ha-1 (Orga) gave the best result in all assessed yield components variables and could be recommended for the study area for high yield and quality tea cultivation.
  Fikre Lemessa and Mulatu Wakjira
  Weeds are important biotic constraints in agroecosystems that interfere with crop plants and consequently reduce yield and quality of crops. An estimated world-wide crop yield loss of about 43% was reported when weeds are left uncontrolled. Agricultural intensification since the 1940s mainly focused on heavy reliance on chemical herbicides to control the weed problem. Nowadays, this is considered objectionable due to the potential negative impacts of herbicide compounds on food safety, non-target organisms, beneficial species, public health and the environment and development of herbicide resistant weeds. Therefore, systems-oriented approaches to weed management that make better use of alternative weed management tactics which are compatible with a specific production system need to be developed. One of such approaches is the use of plants with strong weed-suppressing ability as a component of integrated crop management. Cover crops are well-suited in such holistic approach as they provide many other agroecosystem services besides suppressing weeds. Living cover crops suppress the development of weed populations through niche pre-emption. Moreover, cover crop residues suppress or retard weed emergence and growth due to both allelopathic and physical effects. In this study, major mechanisms were reviewed through which cover crops serve as ecological weed management.
  Fikre Lemessa , Waktole Sori and Mulatu Wakjira
  Common bean (Phaseolus vulgaris) production in the tropics is usually limited by damage due to Angular Leaf Spot (ALS) caused by Phaeoisariopsis grisola. Field experiments were conducted in 2005, 2006 and 2007 at Jimma, Ethiopia, to determine the amount of yield loss due to ALS and to investigate the relationship between ALS and bean yield. Different levels of disease severity were created on two common bean varieties (GLPX-92 and ICA15541) using natural epidemics by spraying the fungicide benomyl at 7-14- 21 and 28-day intervals and by seed dressing. Generally, all fungicide sprays significantly reduced ALS severity and increased yield and seed weight but seed dressing did not affect significantly. The relative yield and seed weight losses to ALS ranged from 2 to 47 and 15 to 33%, respectively. Single-point regression models predicted that for each per cent increase in ALS severity, there was a seed yield loss of 18 to 124.5 kg ha-1 in GLPX and 12.9 to 103.9 kg ha-1 for ICA15541 and 100-seed weight loss per sample of 100 seeds of 10 to 13 g for GLPX-92 and 13 to 22 mg for ICA15541. The study suggests that fungicide sprays affect ALS epidemics and influence the amount of loss in yield attributable to ALS permitting the crop to reach physiological maturity without being under severe infection. Thus fungicide sprays can be used as a means to reduce ALS severity and increase common bean yield.
  Sihen Getachew , Girma Adugna , Fikre Lemessa and H. Hindorf
  Coffee diseases are presumed to be less important in the forest coffee as compared to the garden and plantation systems of coffee production in Ethiopia. In this article, the results of a study conducted on the occurrence and incidence of Coffee Wilt Disease (CWD) and the major factors influencing the disease in four major forests coffee sites in southwest and southeast Ethiopia are discussed. In each forest coffee site, coffee wilt syndrome was assessed in three systematically selected sample plots during dry and wet seasons of 2008 and 2009. Concurrently, three to four samples of infected coffee trees were randomly collected from each plot and the causal pathogen was isolated and identified in the laboratory. The result indicted that CWD was prevalent in the four forest coffee sites, with mean incidence of 27.1 and 29.2% in Harenna during 2008 and 2009 wet seasons, respectively, followed by Berhane-Kontir with mean incidences of 22.1 (2008) and 27.7% (2009). Whereas, Bonga and Yayu forest coffees had comparatively low wilt severity (<10%). The wood samples of most of the infected coffee trees (90.6%) yielded Gibberella xylarioides in the laboratory proving that this pathogen is the main cause of coffee tree death in the forest. The difference in incidence of CWD across the four sites and among fields was strongly associated with human factors and variations in coffee populations. The forest coffee trees in Harenna and Berhane-Kontir (high CWD) are almost transformed to semiforest type by sub-planting coffee seedlings after thinning the dense vegetation cover. These activities are known to create wound to the host and disseminate the fungus spores from tree to tree and from one field to the other. The two independent seedling inoculation tests in the greenhouse evidenced that there were significant variations among coffee accessions in reactions to CWD though most accessions were susceptible. The study showed that CWD is one of the potential biotic factors threatening the genetic diversity of Arabica coffee in most forest coffee sites and thus the disease management practices should duly be considered in planning and implementing forest coffee conservation strategy.
  Derib Alemu , Fikre Lemessa , Mulatu Wakjira and Gezahegn Berecha
  Tomato (Lycopersicon esculentum Mill.) is one of the most widely grown vegetables in the world including Ethiopia. However, its production is constrained by different abiotic and biotic factors. Among biotic factors, bacterial wilt caused by Ralstonia solanacearum is one of the most important pathogens, threatening the production of tomato and potato in Ethiopia. So far there is no single means that would totally manage the disease and provide an absolute cure or fully protect host plants against the pathogen. Hence it is important to look for alternative mechanisms of disease management that can be used as an integrated disease management scheme. This study was, therefore, initiated with the objectives of evaluating the antibacterial activities of aqueous and solvent (acetone and methanol) extracts of five invasive alien species (Eichhorina crassipes, Mimosa diplotricha, Lantana camara and Prosopis juliflora) against R. solanacearum. In vitro antibacterial test was carried out in disc diffusion sensitivity test in a completely randomized design with three replications. It is evident from the result that most of the plant extracts exhibited significant inhibition of the bacterial growth compared with the control. Aqueous extract of E. crassipes provided the highest inhibition zone (26 mm), followed by M. diplotricha (14 mm). After in vitro screening, four promising invasive alien species extracts (aqueous extracts of E. crassipes, M. diplotricha, L. camara and methanolic extract of P. juliflora) with inhibition diameter>10 mm were selected and Minimum Inhibitory Concentration was assessed in vitro. They were also evaluated on tomato plants by applying the botanicals at three time of application (at the time of inoculation and 2-days before and after inoculation). The result of current study revealed that most of the treatment combinations significantly reduced percent disease severity index, but the inhibitory activities of tested plant species were reliant on type of plant species and their application time. More than 91% reduction in percent severity index of bacterial wilt was observed in tomato plants treated with leaf extract of E. crassipes when it was applied at a time of inoculation. The result suggested a need to continue research on invasive alien species extracts and determine their active principles to develop environmentally friendly management approach against bacterial wilt of tomato.
  Ayantu Tucho , Fikre Lemessa and Gezahegn Berecha
  Mango (Mangifera indica L.) is grown in different agro-ecologies of Ethiopia and its production and productivity is limited by several biotic and abiotic factors. Mango anthracnose, caused by Colletotrichum gloeosporioides is considered as the most important mango disease in the country that contribute significantly to pre and post harvest fruit losses. However, the distribution and occurrence of mango anthracnose both in the field and at market in mango producing areas of southwestern Ethiopia is not yet documented. In this study, distribution and occurrence of mango anthracnose in three potential mango producing districts and one urban area in Jimma region, SW Ethiopia were assessed. At the same time knowledge and attitude of farmers against mango anthracnose was also assessed. The results showed that mango anthracnose was 100% prevalent in the study area. Anthracnose incidence and severity varied across farmer’s field and market places. The disease incidence under farmer’s fields ranged from 41-72.1% on leaf and from 36.2-74% on fruit. We found higher (95.3 vs. 82%) and lower (70.7 vs. 64%) incidence and severity in the market, respectively. The disease was more severe in the market place than in the farmer’s fields. It was confirmed that the identified fungus was C. gloeosporioides. So, for better understanding of the prevalence and distribution of this disease and to design appropriate management options, similar assessments across different mango growing agro-ecologies and along mango value chain is crucial.
  Fikre Lemessa , Amsalu Abera , Girma Adunga and Weyessa Garedew
  Coffee (Coffea arabica L.) bean quality can be affected by a number of factors of which storage fungi are one of the major ones. In Ethiopia coffee is a number one export commodity supporting the national economy but there was little information about the association of mycoflora with coffee beans. Therefore, the objective of this study was to assess the associations of mycoflora with coffee seeds and their effect on coffee infection at Limmu Coffee Plantation. The comparison was done using two coffee berry disease resistant selections (74112 and 74110) with and without parchment and with and without surface treatment of coffee beans with 5% sodium hypochlorite and storing under two storage conditions (local cold house and corrugated iron warehouse). Thus, the experiment was laid down as 2×2×2×2 factorial experiment with four replications. The study showed the association of four fungal species (Fusarium spp., Aspergillus spp., Penicillium spp. and Mucor spp.) and some unidentified species in both blotting and agar plating techniques. In general, significantly higher infection percentage was found in coffee seeds without parchment and surface disinfection irrespective of the storage type and coffee selection. Thus, keeping coffee beans with parchment and disinfecting by disinfectants may reduce the association and prevalence of mycoflora on coffee and minimize postharvest problems.
  Binyam Tsedaley , Girma Adugna and Fikre Lemessa
  Background: Sorghum (Sorghum bicolor L., Moench) is the 5th most important food crop in the world. But its production in Ethiopia is adversely affected by different biotic and abiotic constraints among which sorghum anthracnose caused by Colletotrichum sublineolum is the major one. Methodology: In this perspective, it is imperative to assess the distribution and severity of sorghum anthracnose along varying agro-ecologies of Southwestern and Western Ethiopia. A total of 117 sorghum farms in 15 districts of 5 administrative zones within two regional states were assessed. Results: The disease was found to be widely distributed in all sorghum growing regions of the surveyed areas with 100% incidence. The severity of sorghum anthracnose varied significantly (p<0.001) among the 15 districts. The highest severity index of about 87.3 was recorded in Nejo while the lowest severity of about 59.5 was estimated in Leka Dulecha district. The disease was strongly influenced by altitudinal gradients, cropping system and weed management practices. Isolates of C. sublineolum collected from different areas showed variations in both cultural characteristics and conidia morphology, though all of them were pathogenic to sorghum but not to maize plants. Conclusion: Since, sorghum anthracnose is highly prevalent and very severe in all regions of Southwestern and Western parts of Ethiopia, giving due attention in developing effective management strategy is critical.
 
 
 
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