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Keywords:

  • Actinomycetes;
  • plant growth promoting rhizobacteria;
  • rhizosphere;
  • soil enzymes;
  • solid state fermentation;
  • wheat growth

Abstract

Aim

To evaluate the plant growth promotion (PGP) potential and soil enzyme production under solid state fermentation (SSF) by most abundant Streptomyces spp. isolated from the wheat rhizosphere and to evaluate their effect on plant growth parameters.

Methods and Results

Actinomycetes were isolated from wheat rhizosphere and screened for PGP activities. Three actinomycete isolates having significantly higher PGP activities (Streptomyces rochei IDWR19, Streptomyces carpinensis IDWR53, Streptomyces thermolilacinus IDWR81) were selected. The soil enzymes production potential of these isolates using soil extract and wheat straw under ssf was assessed. Utilization of soil extract as a fermentation medium for soil enzyme production by Actinomycetes has been reported first time in this study. Maximum chitinase (S. rochei IDWR19 12·2 U mg−1 protein) and phytase activity (S. carpinensis IDWR53 5·2 U mg−1 protein) was produced on 7th day of incubation, whereas maximum alkaline protease (S. rochei IDWR19 3·2 U mg−1 protein) was produced on 6th day of incubation. For cellulase (S. rochei IDWR19 7·4 U mg−1 protein) and invertase (S. carpinensis IDWR53 451 U mg−1 protein) maximum activity was observed on 4th as well as 5th day of incubation. On the basis of PGP activity and enzyme production, two actinomycete isolates (S. rochei IDWR19 and S. thermolilacinus IDRWR81) were selected for plant growth experiment. An increase of 12·2 and 24·5% in shoot length of plants inoculated with S. rochei IDWR19 and S. thermolilacinus IDWR81 was observed, respectively. A similar increase in biomass of 1·8- and 2·3-fold was also recorded for the two isolates, respectively.

Conclusions

It could be concluded that Streptomyces sp. with high PGP activities and soil enzyme production capability significantly improved growth and development of wheat cv.

Significance and Impact of the Study

The abundant Actinomycetes obtained in this study (S. rochei IDWR19 and S. thermolilacinus IDWR81) are rhizosphere competent and effective strains.