Benefits of ammonium fertilization for plant-PGPM interactions

Joint Conference on 6^th Annual Conference on Microbiology & Annual Conference on Microbes and Beneficial Microbes

October 16-17, 2017 Baltimore, USA

I K Mpanga, N Gomez, J Geistlinger, U Ludewig, N Moradtalab, F Freytag, S Wanke and G Neumann

Universit�¤t Hohenheim, Germany
Anhalt University of Applied Sciences, Germany

Scientific Tracks Abstracts: J Med Microb Diagn

Abstract :

Attempts to use soil microorganisms with potential for nutrient mobilization as inoculants to improve nutrient acquisition of crops have a long history. However, a major limitation of these approaches is a frequently limited reproducibility of effects under practical conditions. Testing a range of commercial products based on Bacillus, Pseudomonas, Trichoderma and Penicillium strains, revealed that the expression of their plant growth promoting potential on maize was strongly dependent on the form of nitrogen supply. Superior performance was recorded in combination with ammonium-based fertilizers, stabilized by nitrification inhibitors instead of nitrate dominated fertilization. A closer examination of the ammonium effects revealed a stronger stimulation of root growth induced by the inoculants, associated with an ammonium-induced elongation of root hairs. Accordingly, ammoniumfertilized maize plants showed higher endogenous auxin (IAA) levels and increased auxin-production potential was demonstrated for Bacillus and Pseudomonas strains in presence of stabilized ammonium, both, on artificial growth media and after-isolation from the rhizosphere. Higher root colonization of maize plants supplied with stabilized ammonium was recorded for a Trichoderma harzianum strain. Moreover, the synergistic effect of microbial and ammonium-induced root growth promotion resulted in a larger root surface area, involved in rhizosphere acidification due to proton-extrusion in response to ammonium uptake, mediating the mobilization of Ca-phosphates and micronutrients such as Zn and Mn. Finally, ammonium fertilization suppressed root infection by the seed-borne pathogenic fungus Fusarium proliferatum. The findings demonstrated that plant-PGPM interactions are strongly dependent on the form of N fertilization offering management options, which have been recently patented.

Biography :

I K Mpanga is currently a PhD Student at the University of Hohenheim, Germany, where he obtained his MSc in Crop Sciences. His work focuses on fertilization strategies to improve plant-growth promotion of microorganisms which is under the just ended European Union Project called Bioeffector chaired by Guenter Neumann at University of Hohenheim, Germany.