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

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


Plant growth promoting rhizobacteria (PGPR) is referred to a heterogeneous group of beneficial rhizosphere
bacteria that could enhance plant yield through one or more mechanisms. Flavobacterium has been noted as
PGPR in almost all review articles. However, there are a few studies regarding plant growth promotion imposed
by them. Some of Plant growth promoting characteristics such as Phosphate solubilizing capacity, ability to use
of 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 from
rhizosphere of wheat. Results showed that none of the isolates were able to produce siderophore, salicylic acid
and chitinase and they were not able to use ACC as well. Determining the siderophore showed that none isolates
did not grow on Chrome Azurol S (CAS) Agar medium. The results of this part were further analyzed using
CAS Agar Diffusion (CASAD) method, but the results were also negative. HCN production was observed in all
isolates, 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 was
a significant negative correlation (r = -0.81**) between solubilized P and the final pH of the growth medium. In
this 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 their
effect on growth and yield of different crop plants.

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