Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 347444
Title Genetic diversity of rhizobia associated with common bean (Phaseolus vulgaris L.) grown under no-tillage and conventional systems in Southern Brazil
Author(s) Kaschuk, G.; Hungria, M.; Andrade, D.S.; Campo, R.J.
Source Applied Soil Ecology 32 (2006)2. - ISSN 0929-1393 - p. 210 - 220.
Department(s) Plant Production Systems
Publication type Refereed Article in a scientific journal
Publication year 2006
Keyword(s) polymerase-chain-reaction - symbiotic nitrogen-fixation - management-systems - microbial biomass - soil - strains - nodulation - populations - host - bradyrhizobium
Abstract Brazil is the largest producer and consumer of the common bean (Phaseolus vulgaris L.), but yields are often low and may be improved by a higher N supply through symbiosis with rhizobia. One main limitation to the N2-fixation process is the susceptibility of the symbiosis to environmental stresses frequent in the tropics, such as high soil temperatures and low soil moisture contents. Among other benefits, the no-tillage (NT) system reduces those stresses resulting in higher N2 fixation rates and yields; however, the effects of NT on rhizobial diversity are poorly understood. This study evaluated the diversity of rhizobia compatible with common bean in cropping areas under the NT or the conventional tillage (CT) systems in Ponta Grossa, State of Paraná, Southern Brazil. Genetic diversity was assessed by DNA analyses using the methodologies of BOX-PCR and RFLP-PCR of the 16S rDNA region. A high level of diversity was observed among the strains and the DNA profiles from the CT system were quite different from those from the NT system. Twenty-three RFLP-PCR profiles were obtained, indicating that many tropical rhizobial species remain to be described. Strain differentiation was achieved in the BOX-PCR analysis; diversity was slightly higher under the NT when compared with the CT system. Surprisingly, the rhizobial grouping based on cluster analysis of the RFLP-PCR of the 16S rDNA region indicated a higher diversity of species under the CT. It could be that the environmental stability offered by the NT system has led to a decrease in the number of species, with the predominance of the most successful ones, although genetic diversity within each species has increased. The results obtained in this study show that we still understand poorly the relation between microbial diversity and soil sustainability and that the complexity of the ecosystems require the evaluation of several parameters to define and monitor soil quality
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