Phenotypic diversity and plant growth promoting characteristics of Mesorhizobium species isolated from chickpea (Cicer arietinum L.) growing areas of Ethiopia

Chickpea (Cicer arietinum L.) is one of the major sources of dietary protein for majority of Ethiopian population. It also maintains soil fertility through its symbiotic nitrogen-fixation in association with Mesorhizobium species. Therefore, this study was aimed at isolation, characterization and selection of symbiotically effective native chickpea nodulating rhizobia endowed with different plant growth promoting (PGP) characteristics. Hence, phenotypic and plant growth promoting characteristics of thirty-six rhizobia isolates recovered from root nodules of chickpea grown in soils collected from different chickpea producing areas found in Central and Northern part of Ethiopia were investigated. The result of our study indicated that chickpea rhizobial isolates have shown wide diversity in their different C and N-sources utilization pattern and tolerance to salinity, high temperatures, acid and alkaline pH, heavy metals and antibiotics. Symbiotic and morphological characterization also showed a wide diversity among tested isolates. Moreover, screening for PGP characteristics indicated that 44.4% of the isolates were phosphate solubilizer while 27.8% of them were found to be indole-3-acetic acid (IAA) producer. Furthermore, 19.4% tested isolates showed antagonistic activity against Fusarium oxysporum in dual culture assay. Generally, the present study indicates that Ethiopian soils contain symbiotically effective chickpea nodulating rhizobia which are endowed with different PGP characteristics.Keywords: Chickpea, Mesorhizobium, plant growth promoting, Ethiopia, symbiotic nitrogen fixationAfrican Journal of Biotechnology Vol. 11(29), pp. 7483-7493, 10 April, 201

Phenotypic, Host Range and Symbiotic

AbstractSoybean is an exotic crop to Ethiopia and may not necessarily have a specific endosymbiont in the soil. However, since it is a promiscuous host, nodulated by cross nodulating rhizobia, it is likely that some compatible endosymbionts exist from heterologous hosts that could nodulate it with effective nitrogen fixation. This necessitated the search for effective indigenous rhizobia isolates and/or compatible and effective cross-inoculating rhizobia that are already adapted to local conditions. To this end, a total of 67 bacterial isolates were trapped from different soil samples using two soybean varieties (Clark-63K and Awassa-95) and one cowpea variety (Bole), to evaluate their diversity and screen for their symbiotic effectiveness. Accordingly, the majority of isolates (93%) were tentatively categorized into alkali producing slow growing Bradyrhiobium spp. and the others (7%) were fast growing and acid producing rhizobia. The isolates showed differences in utilizing various carbon and nitrogen sources and tolerance to acidity, salinity and temperature. The isolates were also diverse in their inherent antibiotic and heavy metal resistance. All the isolates were able to nodulate soybean variety Clark-63K with significant difference in their capacity to infect and effectively fix nitrogen evidenced from variations in nodulation parameters and shoot dry weights. Accordingly, the isolates induced nodulation with nodule number ranging from 2 to 49 nodules plant-1; nodule dry weight of 16 mg plant-1 to 94 mg plant-1 and shoot dry weight between 585 and 1012 mg plant-1. Using shoot dry weight as an indicator of the relative effectiveness of the isolates, 12% of the isolates were highly effective (SE > 80%) and 88% were effective (SE from 50 to 80%) on soybean. Furthermore, the isolates showed narrow and broad host ranges on four legume species viz., cowpea, mung bean, pigeon pea, and peanut. Accordingly, many isolates (67%) formed nodules with effective nitrogen fixation with cowpea (Vigna unguiculata), pigeon pea (Cajanus cajan) (47%), and on few cases with mung bean (Vigna radiata) showing different level of effectiveness. However, the data showed very narrow host range on peanut (Arachis hypogaea) where, only one isolate formed effective nodules

Diversity and abundance of arbuscular mycorrhizal fungi associated with acacia trees from different land use sysetms in Ethiopia

201

Reaction of some rumen micro flora to different supplementary feeds in rumen fistulated animals

Ruminant animals lack enzymes to break down fibrous feeds but they harbor microorganisms capable of degrading their feeds. Rumen microbes are affected by feed substrates. The purpose of this study was to evaluate rumen microbial changes as the function of varying supplementary feeds. Two protein supplements (cottonseed cake and tree lucerne) and two energy supplements (wheat bran and molasses) were offered to rumen fistulated oxen of two groups varying in age. The supplements vary mainly in protein and fibre contents. Switch over design was used in the experiment and the oxen were switched to another supplement after one week to avoid the carryover effect. Microbial populations, correlations with feed nutrient composition and enzyme assays in each case were studied and JMP 5.1 computer software was used for the analysis. Both the bacterial and fungal populations were the highest in oxen supplemented with cottonseed cake (10.7x1011cfu/ml bacteria & 10.8x105cfu/ml fungi) in both young and older oxen (7.4x1010cfu/ml bacteria and 7x105cfu/ml fungi), respectively. The total microbial populations were higher in younger groups supplemented with similar supplement than the older groups of oxen and the least microbial count was observed in those supplemented with tree lucerne (Chamaecytisus palmensis). The enzyme activities were also compared and showed significant variations and linear relation with the nutrient compositions of the feeds. A supplement rich in both fibre and protein supported dynamic rumen microbial population and is very important for the production of quality animal products

Effect of phosphate solubilizing bio-inoculants and vermicompost application on mineral uptake and growth of coffee (Coffea arbica L.) seedlings under greenhouse condition

Arabica coffee (Coffea Arabica L.) is an economically important crop with the highest export revenue in Ethiopia. This study was designed to evaluate the bacterial and fungal phosphate solublization efficacy and to determine yield attributes of coffee seedlings under glasshouse conditions. The study was conducted at Jimma Agricultural Research Center.  The experiment was done with completely randomized design (crd) in three (3) replications. Three potent bacterial isolates viz., rchvcb1, RScB1.19 and RMaB2.11 and three potent fungal isolates viz., rscf1.19 rlvcf2 and rchvcf2 were obtained from Jimma University, Veterinary Medicine, Microbiology Laboratory. The three bacterial isolates were tested for antimicrobial resistance pattern and for their potential to serve as bio-control agents. All the bacterial isolates showed 100% resistance to all the six antimicrobials tested. The growth of pathogenic Fusarium xyloriodes was slightly inhibited by rscf1.19. Single inoculation of rscf1.19+Phosphate  fertilizer and dual inoculation of rscf1.19 and rchvcb1 with P fertilizer significantly (p<0.05)  increased plant height, root length, stem girth, leaf number, leaf area, fresh and dry weights of coffee seedlings. However, all the treatments combined with vermicompost showed suppressive characteristics with no   seedlings emergency at all. rscf1.19 and rchvcb1 can be recommended as bio-fertilizers after conducting necessary field trials in order to    reduce the cost required for chemical fertilizers

Arbuscular mycorrhizal fungi associated with shade trees and Coffea arabica L. in a coffee-based agroforestry system in Bonga, Southwestern Ethiopia

In a first step to understand the interactions between Coffea arabica L. trees and mycorrhizae in Ethiopia, an investigation of the current mycorrhizal colonization status of roots was undertaken. We sampled 14 shade tree species occurring in coffee populations in Bonga forest, Ethiopia. Milletia ferruginea, Scheffiera abyssinica, Croton macrostachyus, Ficus vasta, F. sur, Albizia gummifera, Olea capensis, Cordia africana, Ehretia abyssinica, Pouteria adolfi-friederici, Pavetta oliveriana, Prunus africana, Phoenix reclinata and Polyscias fulva. Coffee trees sampled under each shade tree were all shown to be colonized by arbuscular mycorrhizal fungi (AM fungi). Four genera and 9 different species of AM fungi were found in the soils. Glomus (Sp1, Sp2, & Sp3 & Sp4), Scutellospora (Sp1 & Sp2) and Gigaspora (Sp1 & Sp2) were found under all 14 shade tree species, whereas Acaulospora (Sp1) occurred only in slightly acidic soils, within a pH range of 4.93-5.75. Generally, roots of the coffee trees were colonized by arbuscules to a greater degree than those of their shade trees, the arbuscular colonization percentage (AC%) of the former being higher than the latter (signifIcant difference at 0.05 level). Though differences were not statistically signifIcant, the overall hyphal colonization percentage (HC%) and mycorrhizal hyphal colonization percentage (MHC%) were shown to be slightly higher under coffee trees than under their shade trees. However, the differences were statistically significant at 0.05 level in the case of HC% values of coffee trees under Pouteria adolf-friederici and MHC% under Cordia africana. Spore density and all types of proportional root colonization parameters (HC%, MHC%, AC% and vesicular colonization percentage, VC%) for both coffee and shade trees were negatively and significantly correlated with organic soil carbon, total N, available P, EC and Zn. Correlation between arbuscular colonization for coffee (AC%) and organic carbon was not significantly positive at a 0.05 level. Incidence of specific spore morphotypes was also correlated with physical and chemical soil properties. Results indicate that AM fungi could potentially be important in aforestation and help to promote coffee production activities in Ethiopia providing an alternative to expensive chemical fertilizer use, and would offer management methods that take advantage of natural systems dynamics that could potentially preserve and enhance coffee production. Key words: aforestation; agroforestry, coffee groves, ecology, integrated production systems, rhizosphere, sustainable agriculture, symbiosi

Phytobeneficial traits of Rhizobacteria isolated from degraded soil and evaluate their effect in augmentation of Acacia (Acacia abyssinica Hochst. Ex Benth) seeds germination

Microbes are an integral component of the soil ecosystem but degraded soil has few native beneficial microbes. This necessitates the characterization of phytobeneficial bacteria having numerous features. The study was initiated to evaluate rhizobacteria enhancing Acacia (Acacia abyssinica) seed germination. Isolates were selected based primarily on phosphate solubilization activity and other traits hydrogen cyanide (hcn), phytohormone, hydrolytic enzyme, siderophore, ammonia. Among isolates, 45% each was categorized as high and medium phosphate solubilizers and the amount was found to range from 195 to 373 µg/mL. The highest solubilization index (SI) 7 was recorded for Acinetobacter BS-27 and 6 for Pantoea BS-38. The maximum P and iaa were produced by Pseudomonas FB-49 (373 and 659.07µg/mL), respectively. Isolates with multiple traits were chosen for seed germination. Accordingly, Agrobacterium RS-79 and Pseudomonas BS-26 showed 100% activity. A 100% seed germination and vigor index (343.33 and 306.67) were observed in Pseudomonas BS-26 and FB-49. Degraded soil is considered a source for phosphate solubilizing and other beneficial bacteria with many traits to be used for seed germination assay

Phosphate solubilization and multiple plant growth promoting properties of rhizobacteria isolated from chickpea (Cicer aeritinum L.) producing areas of Ethiopia

Chickpea is one of the major legume crops widely grown in Ethiopia. The low availability of phosphorus in soil is among the stresses that constrain the production of this crop in the country. However, there are rhizobacteria capable of solubilizing insoluble forms of phosphorus in soil and make it available to the plant. Thus, this study was aimed at isolation and characterization of phosphate solubilizing bacteria from chickpea rhizosphere. Fifty phosphate solubilizing bacterial strains were isolated from the soil samples, characterized biochemically and identified by 16S rDNA sequences analysis. The results indicate the presence of genera Acinetobacter, Bacillus, Brevibacillus, Burkholderia, Empedobacter, Enterobacter, Pseudomonas, Ralstonia, Sphingomonas and Stenotrophomonas. Phosphate solubilizing efficiencies of the strains were analyzed using different insoluble phosphorus sources and the results show that most isolates released a substantial amount of soluble phosphate from tricalcium phosphate, rock phosphate and bone meal. Screening for multiple plant growth promoting attributes showed that 44 and 18% of them were capable of producing indole acetic acid and inhibiting the growth of Fusarium oxysporum under in vitro conditions, respectively. A direct impact of several strains (Bacillus flexus (PSBC17), Pseudomonas fluorescence (PSBC33), Enterobacter sp. (PSBC35), Enterobacter sakazaki (PSBC79) and Enterobacter sp. (PSBC81)) on the growth of chickpea in pot culture has been demonstrated by the increase in the number of root nodules, shoot dry matter, nitrogen and phosphorus concentration of shoot. Based on the results, we conclude that chickpea rhizosphere harbor phosphate solubilizing bacteria which are diverse in taxonomy and phosphate solubilizing efficiencies. Thus, consecutive studies should focus on field studies on those strains due to their potentially high importance for the phosphorus nutrition of crops in this area and in this context for the improvement of the sustainability of crop production in the country.Keywords: Plant growth promoting rhizobacteria (PGPR), indole acetic acid (IAA), rhizosphere soil, rock phosphate, bone mea

Guideline for soil biology data collection in Ethiopia: National standard

Recently, recognition has been growing of the power of data and information for better decisionmaking and service provision in agriculture. To ensure good data quality, an agreed standard to collect, store, and share data along the agricultural value chain is required. With this background, the purpose of this guideline is to provide guidance on standardizing soil biology data collection and thereby enhance temporal and spatial data interoperability. Standard field research design, data collection, and data reporting are required for well-informed meta-analyses and syntheses of agricultural research data as well as for making these data more accessible for calibration and evaluation of process-based models. Hence, this guideline is a contribution toward enabling meta-analysis of different data collected over years and/or space to accumulate evidence and generate new knowledge or insights to facilitate informed decision-making in the agricultural sector in general and in the crop development subsector. This guideline is compiled and intended for use by researchers, academicians, students, and other interested professionals in Ethiopia and beyond. The guideline is developed based on accepted standards and procedures in the field. Nevertheless, it is not exhaustive in its coverage of the soil biology data types and crops grown in the country. Hence, additions and updates depending on the development of research facilities, the ever-changing focus of agricultural research and production systems, and advances in technology are warranted

Phenotypic Diversity in Ethiopian Chickpea (Cicer arietinum L.) Germplasm Accessions for Phosphorus Uptake and Use Efficiency

Ethiopia is known as the secondary center of diversity for chickpea (Cicer arietinum L.). Plant breeders primarily interested in utilizing the available  germplasm for improving phosphorus uptake and use efficiency have no background information on the genetic diversity for this attribute. A field study  involving 155 chickpea genotypes was undertaken at Ambo and Ginchi, Ethiopia, in 2009/2010 to characterize the genotypes for nutrient uptake and use  efficiencies. Cluster analysis grouped the genotypes into five clusters in the absence and six clusters in the presence of phosphorus. The higher number  of clusters when the crop was grown with phosphorus may be a manifestation of more genetic diversity due to the application of phosphorus. The  Mahalanobis’s D2 statistics mostly showed significant genetic distances between clusters constituted local landraces on the one hand and introduced  genotypes on the other. This indicated that there were distinct multivariate differences between landraces and introduced genotypes. No clear  interrelationship was observed between the origins of the landraces within Ethiopia and the pattern of genetic diversity. Different characters had  different contribution to the total differentiation of the populations in all the cases. The result of this study suggests existence of adequate genetic  diversity for attributes of phosphorus uptake and use efficiency in these chickpea genotypes, which should be exploited in future breeding.&nbsp