Tillage method and crop rotation effects on the population sizes and diversity of bradyrhizobia nodulating soybean

• Published in: Soil biology & biochemistry Vol. 32; no. 5; pp. 627 - 637
• Main Authors: Ferreira, Magda C., de S. Andrade, Diva, de O. Chueire, Ligia Maria, Takemura, Solange M., Hungria, Mariangela
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2000; New York, NY Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Bacteria diversity; Biological and medical sciences; Bradyrhizobium; Crop rotation; Cropping systems. Cultivation. Soil tillage; Economic plant physiology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Glycine max; Nitrogen fixation; Soil tillage; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Tillage system; Tillage. Tending. Growth control; South America; Brazil; America; Bacteria diversity; Nitrogen fixation; Tillage system; Crop rotation; Bradyrhizobium; Genetic marker; Agricultural system; Tropical zone; Plant nodule; Sustainable agriculture; Dicotyledones; Angiospermae; Bacteria; Greenhouse study; Cultural practice; Symbionte; Soil tillage; Cropping system; Microbial biomass; Glycine max; Random amplified polymorphic DNA marker; Grain legume; Leguminosae; Morphology; Fingerprint method; Serological method; Isolate; Spermatophyta; Rhizobiaceae
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(99)00189-3

This study was conducted in an area of Brazil cultivated with soybean since the early 1960's but which for the last 17 yr was under different tillage (no-tillage, NT; conventional tillage, CT) and crop rotation (soybean, S/wheat, W/maize, M; S/W; M/W) systems. The area had not received any inoculant for the last 15 yr and our objective was to investigate the effects of tillage and cropping systems on the bradyrhizobia population. The NT system and crop rotations with soybean resulted in high populations of bradyrhizobia, but even in the treatment where soybean had not been cultivated for 17 yr (M/W) the number of viable cells in the soil was high. A total of 142 bradyrhizobia isolated from the different treatments were characterized based on colony morphology, serological reaction, DNA analysis by RAPD, protein and Nod factors profiles. The analyses resulted in grouping of the isolates into 16 DNA, five protein and three Nod factors profiles. A high proportion (37.5%) of the isolates did not react with any known serogroup. Both NT and crop rotations with soybean resulted in a higher bradyrhizobia diversity, with the lowest number of genomic patterns occurring in the CT with M/W rotation. However, there was no relationship between the treatment combinations and genetic relatedness. The evaluation of symbiotic performance under greenhouse conditions showed that the isolates with higher rates of N 2 fixation were also isolated from NT with S/W or S/W/M crop rotations. Consequently, the use of agronomic practices such as NT and crop rotation with legumes will not only contribute to agricultural sustainability, but also help to maintain bradyrhizobia population and diversity.