|San Francisco, Michael|
Submitted to: American Society of Microbiologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2008
Publication Date: 11/11/2008
Citation: Kumar, S., Dowd, S., Acosta Martinez, V., McMichael, B.L., Jeter, R.M., San Francisco, M., Zak, J. 2008. Bacterial diversity in peanut rhizosphere in a semi-arid climate: impacts of nitrogen fertilization. South Central Branches of the American Society of Microbiologists. November 9-11, 2008. Austin, Texas. Interpretive Summary:
Technical Abstract: Rhizobacteria can play important roles in agronomic ecosystems impacting nutrient availability, nutrient uptake, and drought responses of plants in many cropping systems. The ability of rhizosphere bacteria to impact plant growth can be negatively impacted through the application of nitrogen fertilizer, which can alter soil microbial diversity. In this study we analyzed the effect of nitrogen fertilizer on bacterial diversity of the peanut rhizosphere in semi-arid west Texas. The treatment consisted of 35 lb/acre (39.23 kg/ha) of ammonium nitrate added at the beginning of the growing season. Plants in control and fertilizer treatment plots were grown in each of two different tillage soils (stripped and conventional-where the previous crop residue was removed) and with no water stress. Soil was collected over a 5-month period (post-seedling stage) from the rhizosphere of peanut plants. DNA prepared from these samples was amplified using bacterial universal 16S-rRNA-encoding gene primers, and the products were subjected to pyrosequencing. Rarefaction analysis was used to determine the influence of added nitrogen on bacterial diversity as defined by Operational Taxonomic Units (OTUs). The number of OTUs was consistently lower in all the soil samples treated with nitrogen fertilizer. Nitrogen fertilization increased the dominance of certain bacteria thereby reducing overall bacterial diversity by suppressing bacteria that could not take advantage of the additional nitrogen. The most dominant bacterial class observed in this study was the actinobacteria (treatment as well as control).