Effects of the inoculation with Bacillus simplex, Pseudomonas fluorescens and Azospirillum brasilense on biomass production, grain yield and native microbial community of wheat plants.

ORTEGA M. DE LOS A.H.,; KADE M; DI SALVO L. P.,; ESCOBAR ORTEGA J. S.,; GARCÍA DE SALAMONE I. E.,; BARNEIX A. J.

Villa Carlos Paz, Córdoba

Congreso; VI CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL (SAMIGE); 2009

Inoculation with Bacillus Simplex, Pseudomonas  fluorescens and Azospirillum brasilense on biomass production, grain yield and native microbial community of wheat plants. Ortega, M. de los A., García de Salomone, I. E., Barneix, A. J.   Cátedra de Microbiología Agrícola, IBYF-CONICET, Facultad de Agronomía, UBA. Av. San Martín 4453 C1417DSE, Ciudad de Buenos Aires.   The prospect of manipulating crop rhizosphere microbial populations by inoculation of beneficial bacteria to increase plant growth has shown considerable promise. The potential environmental benefits of this approach, leading to a reduction in the use of agricultural chemicals and the fit with sustainable management practices, are driving this technology. Plant growth promoting rhizobacteria (PGPR) enhance plant growth by direct and indirect means, but the specific mechanisms involved have not all been well-characterized. PGPR have been reported to directly enhance plant growth by a variety of mechanisms: fixation of atmospheric nitrogen that is transferred to the plant, production of siderophores that chelate iron and make it available to the plant root, solubilization of minerals such as phosphorus, and synthesis of phytohormones, while indirect mechanisms involve the ability of PGPR to reduce the deleterious effects of plant pathogens on crop yield. The present work proposes to study the effect of wheat Triticum aestivum L. cv. ProINTA Isla Verde inoculation with PGPR strains on biomass, yield and native microbians community. The experiment was performed in a greenhouse in a completely randomized blocks design.  Inoculation treatments consisted of no inoculation, or Bacillus simplex BS BNM-10, Pseudomonas fluorescens Sp233 and Azospirillum brasilense Sp245. Three samplings were carried out: 100% emergent principal ear, 10 days after anthesis and harvest. Plant material was dried at 60ºC for 48hs. and weighed. Rhizosferic microbians community physiology was studied through profiles of use of carbon substrates (CLPPs).  Azospirillum increased root dry weight in the first sampled. In the second sampled, both treatments, Azospirillum and Peudomonas increased air, ears, and roots biomass. However grain yield was not increased. On the other hand, in the CLPPs analysis, the average of inoculation treatments were significantly different compared with no inoculation treatment in the first sampled, but not in the next sampled.   Our finding show that rhizobacterias impact was temporary, because probably these rhizobacterias were not competent and they could be quickly displaced for native microbians community, reverting like that the initial impact.