IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

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17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Title Nitrogen fixation promotes accumulation of dietarily-important mineral nutrients in edible leaves of cowpea (Vigna unguiculata l. Walp.) Authors Alphonsus K. Belane 1 and Felix D. Dakora 2* Poster Board Number 29 1 Department of Crop Science, and 2 Department of Chemistry, Tshwane University of Technology Cowpea leaves are a major source of dietary mineral nutrients for many households in rural Africa. Little is however known of the relationship between cowpea symbiosis and mineral accumulation in its edible leaves. This study evaluated 30 field-grown cowpea genotypes at Wa and Manga in Ghana, and Taung in South Africa, for N2 fixation and mineral density using the 15 N natural abundance technique and inductively coupled plasma mass spectrometry respectively. The mean levels of leaf minerals presented here are for the highest and lowest N2-fixing cowpea material taken from a study of 30 genotypes. The results showed that, at Wa in Ghana, IT90K- 76, Bensogla and Glenda produced the largest biomass per hectare, fixed the highest amount of symbiotic N, and showed much higher concentrations and amounts of trace elements and macronutrients in edible cowpea leaves. In contrast, genotype ITH98-46, which recorded the least biomass, fixed the lowest amount of symbiotic N, and exhibited the lowest concentrations and amounts of mineral nutrients in its leaves. The data for Manga in Ghana and Taung in South Africa showed a similar pattern; the highest N2-fixing genotypes indicated better plant growth and greater mineral accumulation compared to their counterparts with little biomass and low N2 fixation. This observation was confirmed by correlation analysis which revealed a significantly positive relationship between mineral nutrients and symbiotic parameters such as δ 15 N, %Ndfa and amount of N-fixed. Thus, in addition to N contribution in cropping systems, the cowpea symbiosis also enhances mineral density in edible leaves for improved human nutrition and health. 144 2011
17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Title Diversity and phylogeny of Bradyrhizobium spp. Isolated from shrub and tree legumes in Ethiopia Authors Aregu Amsalu Aserse 1,2 , Leena.A.Räsänen 1 ,Fassil Assefa 2 , Asfaw Hailemariam 3 and Kristina Lindström 1 Poster Board Number 30 1 University of Helsinki, Department of Food and Environmental Sciences, 2 Addis Ababa University, Cellular, Microbial and Molecular Biology Program Unit 3 National Soil Testing Centre, In Eastern Africa including Ethiopia, crop production has been affected by recurrent drought, deforestation and losses of soil fertility. Soil fertility is the major constraint and nitrogen is considered as one of the most limiting nutrients in the region. Nitrogen-fixing shrubs and tree legumes, such as Crotalaria, Erythrina and Indigofera species have been used in agroforestry systems (home-gardens, fallows and land reclamation) to improve the availability of nitrogen in the soil. Soybean is an exotic crop legume in Ethiopia and its symbionts capable of forming nitrogen-fixing nodules do not exist in the soil. Inoculation of soybean has not always been successful. Therefore, effective rhizobial strains that are adapted to their local environments are required. Interestingly, indigenous rhizobial strains, which nodulate leguminous shrubs and trees have been found to infect soybean as well. However, knowledge on the symbionts of different leguminous plants in Ethiopia is scarce. Therefore, the aim of this study was to explore the diversity and phylogeny of indigenous Bradyrhizobium strains isolated from Crotalaria incana, Erythrina brucei, Indigofera arrecta and Gycine max. Fifty-five strains were isolated from nodules collected at 29 sites located mainly in southwestern Ethiopia. The diversity of the bacterial collection was studied using amplified fragment length polymorphism (AFLP) fingerprinting. The strains were preliminary identified by comparing the partial sequences of the 16S rRNA gene against a nucleotide database. For further phylogenetic studies, the housekeeping genes recA, rpoB and glnII were sequenced. Phylogenetic trees of these genes as well as phylogenies of the symbiotic genes nodA and nifH will be presented together with strains symbiotic capacity and plant growth promoting activities. 145 2011
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PrinciPal SPonSor: SPonSorS: Progra
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INVENTING THE FUTURE IN INOCULANTS
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17 ICNF Organising Committee Graham
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Cottesloe Beach © Tourism Western
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GeNeRAl INfoRmATIoN aTM’s Automat
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16:30 - 16:50 Felix Dakora Tshwane
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Thursday 1 December 2011 08:00 - 12
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