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Articles by Gezahegn Berecha
Total Records ( 9 ) for Gezahegn Berecha
  Melkamu Tiru , Diriba Muleta , Gezahegn Berecha and Girma Adugna
  This study was designed to evaluate the antagonistic effects of rhizobacterial antagonists against Coffee Wilt Disease (CWD) caused by Gibberella xylarioides under in vitro and in vivo conditions. Arabica coffee is Ethiopia’s main export crop. However, the production and productivity of coffee is being challenged primarily by coffee vascular disease (tracheomycosis).The greenhouse antagonism study was conducted with four antagonistic bacteria of one Bacillus (JU544) and three Pseudomonas spp. (JU941, JU13 and JU23). Out of 81 rhizobacterial antagonists tested on Half Strength King’s B (HSKB) medium against G. xylarioides, 13.6% of them significantly (p<0.0001) reduced the radial mycelial growth of the pathogen. From 11 rhizobacterial isolates tested for their phytobeneficial traits, eight of them produced protease. Nevertheless, five of them produced Hydrogen Cyanide (HCN) and other lytic enzymes. The bio-control agents, time of applications and the interaction of the two were significantly (p<0.0001) reduced the CWD severity and incidence under greenhouse conditions. The CWD control efficiency was significant (p<0.0001) and the highest bio-control efficiency was 72.64% when the coffee seedlings were treated with Bacillus spp. (JU544) seven days before the pathogen. The bacterial antagonists, time of applications and interaction of the two significantly (p<0.001) reduced the progression of CWD incidence. The rhizobacterial antagonists especially Bacillus spp. (JU544) effectively reduced CWD severity and incidence under greenhouse condition and can be further evaluated under field condition to ascertain their future applicability for inoculum development.
  Hinsene Garuma , Gezahegn Berecha and Chemeda Abedeta
  In Ethiopia, coffee production system can mainly be categorized as; garden, plantation, semi-forest and forest coffee production systems which are assumed to vary in the intensity of management. But, little is known whether these production systems and the associated management practices have effect on coffee beans abnormalities. Besides, the role of pea berry on cup quality parameters has not been documented under Ethiopian condition. Therefore, the study was carried out to assess the influence of coffee production systems on the occurrence of bean abnormality and cup quality. The study was carried out in the landscape matrix of forest and agricultural lands near Jimma, in South-western Ethiopia. A total of 24 study sites in four production systems were sampled. Coffee cherries were prepared following the standard procedure for wet method of processing. The beans sensory quality was tested with and without pea berry (the major bean abnormality observed in this study). Coffee production system showed significant influence on the occurrence of bean abnormality. Plantation coffee production system showed significantly higher proportion of pea berry which accounts for higher portion of bean abnormality than the rest of production systems (p<0.001). There was no significant difference between the coffee beans tested with and without pea berry in all of the production systems except body in the garden coffee production system, where the coffee tested with pea berry gave the lower grade while coffee tested without pea berry scored the highest grade. In conclusion, an evidence was not generated for the negative effect of pea berry on coffee quality. However, future study was recommended on the causes of bean abnormalities in coffee across coffee production systems as occurrence of pea berry may have yield implication.
  Mulatu Wakjira , Gezahegn Berecha and Befekadu Bulti
  The current study was conducted to test the inhibitory potential of aqueous extracts and dry shoot residues of four multipurpose tree species (Albizia gummifera, Azadirachta indica, Melia azedarach and Sesbania sesban) on seed germination and seedling growth of an invasive alien weed Parthenium hysterophorus under laboratory and greenhouse conditions. Leaf aqueous extracts and dry residues of all the multi-purpose tree species drastically inhibited germination and seedling growth of parthenium. Parthenium radicle was more inhibited than plumule in Petri dishes. Inhibitory effects increased with increasing aqueous extract concentration and residue amount. Soil surface-placed leaf residues exerted strong reduction on germination and growth of parthenium than soil-incorporated residues. In contrast to the higher inhibitory effects in Petri dishes, lower inhibitory effects were observed by the aqueous extracts of the multi-purpose tree species in pot-culture. Therefore, further investigations will be required under greenhouse and field conditions for pragmatic recommendation of species selection in the frame of multi-purpose tree species-mediated ecological management of parthenium weed.
  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.
  Shiferaw Demissie , Diriba Muleta and Gezahegn Berecha
  The aim of this study was to evaluate effect of phosphate solubilizing bacteria on seed germination and seedling growth of Faba bean (Vicia faba L.) under lath-house condition. Phosphorous is an essential macronutrient next to nitrogen required by the plants for vital biosynthesis. But often unavailable for plants because of adsorbed by Ca2+, Mg2+, Fe2+ and Al3+ ions through legend exchange. Although there is mounting information that phosphorus solubilizing bacteria as inoculants increases P uptake of plants. This was not yet tested on Faba bean in Ethiopia. A total of 183 phosphate solubilizing bacteria were isolated from 150 samples collected from rhizosphere soil and root nodules. From these isolates based on their solublization index and mobilization efficacy, two isolates (JURB48 and JURMB69) were selected and tested on Faba bean. The co-inoculants (JURB48+JURMB69) increased the percentage of seed germination (21.4%), vigor index (46.2%), radicle (25.3%) and plumule (50%) lengths of germinated seeds of Faba bean over the non-inoculated. Faba bean shoot fresh, root weight, leaf number, flower number, root dry weight and total dry matter were significantly increased compared to non-inoculated as a result of co-inoculants (JURB48+JURMB69). Plant height, root length, phosphorus content, P uptake and Nodule number and weight were enhanced due to inoculation with JURB48 and JURMB69, respectively, compared to non-inoculated either in the presence or absence of phosphate sources. The present study suggests the potential of JURB48 and JURMB69 isolates as biofertilizers for Faba bean cultivation.
  Bayu Dume , Gezahegn Berecha and Solomon Tulu
  Physical and chemical properties of the biochar varied as a function of feedstock selection and pyrolysis temperatures. Biochar additions to acidic soils have the potential to improve soil fertility and crop yield. Biochar materials were produced from coffee husk and corn cob at temperatures of 350 and 500°C and characterized by their physical and chemical properties. These were mixed with acidic soil at the rates of 0, 5, 10 and 15 t ha–1 and were laboratory incubated for 2 months at ambient temperature to examine changes in soil properties. Types of feedstock used at two different pyrolysis temperatures and application rate had no significant effects on soil textural classes but showed highly significant effects (p<0.01) on soil pH, Electrical Conductivity (EC), Cation Exchange Capacity (CEC), Organic Carbon (OC), Organic Matter (OM), Total Nitrogen (TN), exchangeable cations and available phosphorous. Application of coffee husk biochar showed relatively better improvement in soil chemical properties (pH, EC, CEC, OC, OM, TN, exchangeable cations and available phosphorous) than corn cob biochar at all application rates. The highest values of chemical properties were recorded when coffee husk biochar produced at 500°C temperature was applied at a rate of 15 t ha–1. Therefore, we generated an evidence that application of biochar is very important to improve physical and chemical properties of acidic soil.
  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.
  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.
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