Effects of Streptomycets on colonization and growth of white clover inoculated with arbuscular mycorrhiza

The presence of some microorganisms including actinomycetes or their metabolites increase the growth of fungal mycelium, roots colonization and plant growth indices. In this study, an experiment was carried out in a completely random design (CRD) with three replications. The effects of four actinomycete species (S. griseus, S. albogriseus, S.sp1 and S.sp2) were examined on the frequency of hyphae, vesicles and colonization of clover root (Trifolium alexandrinum) inoculated by Rhizophagus irregularis. Wet and dry weight and phosphorus concentrations were measured in shoot and root of clover. The results showed that mycorrhizal symbiosis greatly stimulated by S. albogriseus and root and shoot growth and phosphorus absorption significantly increased in shoot and root of clover. Three species of actinomycetes considerably improved the fungal organs frequency in clover root, and the percentage of root colonization increased from 48.61% (in control) to 86.59, 72.93% and 66.90% in S. albogriseus, S. griseus, and S. sp2 treatments respectively. The frequencies of hyphae in clover roots increased from 45.32% (in control) to 92.55, 85.48 and 71.47% S. albogriseus, S. griseus, and S. sp2 treatments respectively. Inoculation of mycorrhizal roots of clover with S. albogriseus significantly increased the wet and dry weight and phosphorus concentrations of clover roots and shoots but S. griseus and S. sp2 treatments increased shoot dry weight and phosphorus concentration in the roots and shoot of clover root. S. albogriseus could possibly be used in the production and preparation of R. irregularis inoculant.