Plant Growth Promoting Characteristics in Some Flavobacterium spp. Isolated from Soils of Iran

Ali-Ashraf Soltani,Hamed Mirhoseyni,Kazem Khavazi,Payman Abaszadeh Dahaji,Hadi Asadi-Rahmani,Mahtab Omidvari

doi:10.5539/jas.v2n4p106

Abstract

Plant growth promoting rhizobacteria (PGPR) is referred to a heterogeneous group of beneficial rhizospherebacteria that could enhance plant yield through one or more mechanisms. Flavobacterium has been noted asPGPR in almost all review articles. However, there are a few studies regarding plant growth promotion imposedby them. Some of Plant growth promoting characteristics such as Phosphate solubilizing capacity, ability to useof 1-Amino Cyclopropan-1-Carboxylate (ACC) as sole nitrogen source and production of auxin, siderophore,salicylic acid, chitinase and hydrogen cyanide were evaluated in forty-four flavobacteria isolated fromrhizosphere of wheat. Results showed that none of the isolates were able to produce siderophore, salicylic acidand chitinase and they were not able to use ACC as well. Determining the siderophore showed that none isolatesdid not grow on Chrome Azurol S (CAS) Agar medium. The results of this part were further analyzed usingCAS Agar Diffusion (CASAD) method, but the results were also negative. HCN production was observed in allisolates, but in lowest limit. Thirty-four isolates were capable to solubilize insoluble inorganic Phosphate (P)sources. The average rate of P-solubilization was 3.54 ?g Pml-1, ranging from zero to 37.48 ?gPml-1. There wasa significant negative correlation (r = -0.81**) between solubilized P and the final pH of the growth medium. Inthis study, all the isolates were able to produce auxin, ranging from 0.27 to 12.03 ?gml-1 averaged by 2.03.Considering the ability of the isolates to produce auxin and for P-solubilization, it is necessary to evaluate theireffect on growth and yield of different crop plants.

Highlights

The rhizosphere as defined by Boven and Rovira (1999) is a tender zone of soil surrounding a plant root where living organisms are influenced by root vital activities qualitatively and quantitatively
44 isolates of Flavobacterium were isolated from wheat rhizosphere were tested for their plant growth promoting qualities
Any isolate couldn’t generate chitinase while the culture media was suitable for responding against chitinase and some of bacteria which were isolated from soil, made a bright halo around themselves (Table 1)

Summary

Introduction

The rhizosphere as defined by Boven and Rovira (1999) is a tender zone (about 1-3mm) of soil surrounding a plant root where living organisms are influenced by root vital activities (like compounds exuded by the root and respiration) qualitatively and quantitatively. PGPR can promote plant development by the suppression of pathogens mediated by different mechanisms such as antibiosis (Milner et al, 1996), iron sequestration by siderophores ( Bar-ness et al, 1992), HCN ( Keremer and Souissi, 2001), vitamin excretion (Streit et al, 1996), and cell wall degrading enzymes like chitinase (Ajit et al, 2006). Plant growth is promoted through reducing or neutralizing pathogen activity

Methods

Results

Conclusion