Variation in microbial responses and Rhizoctonia solani AG2-2IIIB growth in soil under different organic amendment regimes

• Published in: Canadian journal of plant pathology Vol. 34; no. 2; pp. 268 - 276
• Main Authors: van Overbeek, Leonard S, Senechkin, Ilya V, van Bruggen, Ariena H. C
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 01.04.2012; Taylor & Francis Ltd
• Subjects: 16s ribosomal-rna; amendement organique; ammonia-oxidizing bacteria; bacteria; beta-Proteobacteria; Carbon; chemical analysis; communautés microbiennes; communities; composts; damping off; disease suppression; farms; fluorescent pseudomonads; fonte des semis; fungi; gradient gel-electrophoresis; microbial communities; multivariate analysis; nitrogen fertilizers; organic amendment; organic matter; pathogens; Pseudomonas; ralstonia-solanacearum biovar-2; Rhizoctonia solani; slurries; soil; soilborne diseases; sol; sugar beet; take-all; Thanatephorus cucumeris
• ISSN: 1715-2992; 0706-0661; 1715-2992
• DOI: 10.1080/07060661.2012.679622

Organic amendments influence chemical and microbial compositions in soils and also susceptibility to plant diseases. The purpose of this study was to establish different parameters that interfere with pathogen growth in soil. Four different organic-amendment regimes, i.e. slurry, compost, slurry-dung and compost-slurry-dung, were applied to two fields proximate to each other on the same farm and covered with the same grass-clover ley in the last two years preceding sampling. Before that period, there were differences in cropping and management practices between both fields. Chemical analyses of the soils revealed no differences between organic amendments, whereas significant differences were present between fields in all C, N and pH values. Growth of R. solani AG2-2IIIB in soil, measured by damping-off in sugar beet plants, was influenced by the interaction of organic amendment with field type. Diversity and evenness values of the microbial communities, studied by PCR-DGGEs specific for bacteria, fungi, Pseudomonas and ammonia-oxidizing β-proteobacteria, revealed different patterns, i.e. no differences between organic amendments, but clear differences between fields. Multivariate analyses done on individual species of the four groups, as represented by band location and size in PCR-DGGE fingerprints, and by inclusion of chemical and R. solani AG2-2IIIB growth parameters as ‘environmental’ variables, revealed strong and occasionally significant effects of organic matter content, water-dissolvable organic carbon and pH on microbial communities. It was therefore concluded that different organic amendments had different effects on pathogen growth in soils of both fields and that organic matter content and pH influenced soil microbial compositions most.