Browsing by Author "Osei Ophelia"

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    Bacteria related to Bradyrhizobium yuanmingense from Ghana are effective groundnut micro-symbionts
    (Elsevier, 2018) Osei Ophelia; Abaidoo R. C; Ahiabor Benjamin D.K.; Boddey Robert M.; Rouws Luc F.M.
    The identification of locally-adapted rhizobia for effective inoculation of grain legumes in Africa’s semiarid regions is strategic for developing and optimizing cheap nitrogen fixation technologies for smallholder farmers. This study was aimed at selecting and characterising effective native rhizobia, from Ghanaian soils for groundnut (Arachis hypogaea L.) inoculation. From surface-disinfected root nodules of cowpea and groundnut plants grown on farmers’ fields, 150 bacterial isolates were obtained, 30 of which were eventually found to nodulate groundnut plants. After testing the symbiotic potential of these isolates on groundnut on sterilized substrate, seven of them, designated as KNUST 1001–1007, were evaluated in an open field pot experiment using 15N labelled soil. Although 15N dilution analyses did not indicate differences among treatments in the proportion of nitrogen (N) derived from the atmosphere (%Ndfa), all seven strains increased total N derived from N2 fixation by inoculated groundnut plants as compared to the non-inoculated control. Inoculation with KNUST 1002 led to total N accumulation as high as that of the groundnut reference strain 32H1. Genetic characterisation of the isolates by sequence analysis of 16S rRNA gene, 16S – 23S rRNA intergenic transcribed spacer (ITS) region and nodC gene revealed that isolates KNUST 1003 and 1007 were related to Rhizobium tropici, a common bean symbiont. The other five isolates, including KNUST 1002 belonged to the Bradyrhizobium genus, being closely related to Bradyrhizobium yuanmingense. Therefore, this study revealed novel native Ghanaian rhizobia with potential for the development of groundnut inoculants
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    Native Bradyrhizobium Strains From Ghana Can Enhance Grain Yields of Field-Grown Cowpea and Groundnut
    (Frontiers in Agronomy, 2020) Osei Ophelia; Abaidoo R. C; Opoku Andrews; Rouws Janaina R. C; Robert M. Boddey; . Ahiabor Benjamin D. K.
    The existence of large population of ineffective native rhizobia and inconsistent performance of exotic strains in Ghanaian soils necessitate the need to identify effective and locally adapted elite strains for enhanced legume-rhizobium symbiosis.This study was designed to test the suitability of two previously selected potential elite Bradyrhizobium strains for use as inoculants on cowpea (Vigna unguiculata L. Walp) and groundnut (Arachis hypogaea L.) in multilocation experiments. Field experiments were set up at 26 locations (12 planted with cowpea and 14 planted with groundnut) in the Northern region of Ghana. Four treatments were applied at each location: inoculation with Bradyrhizobium strains KNUST 1002 and KNUST 1006, a positive nitrogen (+N) control and a negative control (without nitrogen or inoculation) arranged in randomized complete blocks with four replications. The results showed that inoculation with strains KNUST 1002 and KNUST 1006 promoted significant increases in grain yields of both cowpea and groundnut. On average, inoculating cowpea with strains KNUST 1002 and KNUST 1006 resulted in 63 and 52% increases in grain yield when compared to the negative control. Pod yields of groundnut, on the other hand, were significantly (p < 0.05) increased at 57% of the study locations with one or both test strains. Responses to inoculation were, however, highly variable across the different study locations (i.e., significant Treatment Location Interaction, TLI). A detailed analysis of this significant TLI based on the genotype main effect (G) plus genotype-by-environment (GE) interaction (GGE) biplot analysis revealed that location contributed 71 and 88% of the variation observed in cowpea and groundnut, respectively, and grouped the locations into mega-environments for cowpea. These results demonstrate that native elite Bradyrhizobium strains KNUST 1002 and KNUST 1006 have potential for use as inoculants to increase cowpea and groundnut production in Northern Ghana.
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    Organic Manure Improves Soybean Response to Rhizobia Inoculant and P-Fertilizer in Northern Ghana
    (Frontiers in Agronomy,, 2020) Ulzen Jacob; Abaidoo R. C; Ewusi-Mensah Nana; Osei Ophelia; Masso Cargele; Opoku Andrews
    Inherently low concentrations of soil nutrients and erratic rainfall pattern in sub-Sahara Africa limit soybean response to rhizobia inoculant and P-fertilizer. The study was conducted to: (i) improve soybean response to rhizobia inoculation and P-fertilizer through the addition of organic manure; (ii) enhance rain water use efficiency and (iii) determine the economic viability of combined application of the three factors in soybean cropping systems in the Northern region of Ghana. A factorial experiment with two levels of rhizobia inoculant, two levels of Phosphorus, two different kinds organic manure [fertisoil (a commercially prepared compost from urban waste, rice husks, of poultry manure and shea butter waste) and cattle manure] and a control arranged in randomized complete block design with three replications was established on farmers’ fields. The combined application of rhizobia inoculant, P-fertilizer, and organic manure markedly increased nodulation, shoot biomass, haulms, harvest index (HI), P agronomic efficiency (P-AE), and rain water use efficiency (RUE) compared to the control. The combined application of rhizobia inoculant, P-fertilizer, and fertisoil increased grain yield by four-folds whereas the combined application of rhizobia inoculant, P-fertilizer, and cattle manure increased grain yield by three- folds. Harvest index, P-AE, and RUE were relatively higher with the fertisoil treatment combinations than with the cattle manure combinations and the control treatment. The application of rhizobia inoculant, P-fertilizer in combination with fertisoil was profitable with VCR of 2 as compared to the combination of cattle manure which had a VCR of 0.40. The results showed that fertisoil offers a better option of improving soybean response to rhizobia inoculant and P-fertilizer; and has the potential to enhance rain water use efficiency. However, the long term benefit must be quantified.
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    PCR assay for direct specific detection of Bradyrhizobium elite strain BR 3262 in root nodule extracts of soil-grown cowpea
    (Springer, 2017) Osei Ophelia; L. Jean; Araújo Simões; Zilli Jerri E.; Boddey Robert M.; Ahiabor Benjamin D. K.; Abaidoo R. C; Rouws Luc F. M.; 0000-0002-1235-2252
    Aims Successful inoculation of legume crops with rhizobia depends on dominating nodule occupancy with highly efficient strains. The aim of this study was to develop a rapid and reliable conventional PCR method ology to specifically detect an elite Bradyrhizobium strain in root nodule extracts from soil-grown cowpea plants. Methods The draft genome sequence of Bradyrhizobium pachyrhizi BR 3262 was compared to the closely related strain PAC 48T .BR 3262-specific regions were selected to design specific primer pairs, which were tested with respect to PCR amplification specificity and efficiency on extracted DNA, bacterial cells and root nodules from cowpea plants grown under gnotobiotic conditions and in soil. Results Eleven designed primer pairs were specific for BR 3262 amplification and two of them (pairs 2645 and 2736) were highly sensitive and selected for further analyses. Experiments with gnotobiotic and soil-grown plants showed that both primer pairs were suitable to reliably determine nodule occupancy and confirmed the competitiveness of strain BR 3262 in natural soil. Conclusions Primer pairs 2645 and 2736 are novel tools to accompany the fate of strain BR 3262 in inoculation experiments of cowpea in soil. This strategy should be applicable to other rhizobium/legume symbioses in the field.