Biocontrol of phytopathogenic fungi of rice crop using plant growth-promoting rhizobacteria

Abstract

Rice is widely affected by quite a number of diseases caused by fungi, bacteria, viruses, and mycoplasma that result in high yield loss. Among the fungal diseases, aggregate sheath spot caused by Rhizoctonia oryzae-sativae is an important disease affecting the rice production. Application of beneficial bacteria as seed coat or seedling root dip to protect from these diseases may be an alternative strategy to chemical control. In the present study, out of 200 bacterial strains isolated from plant rhizosphere of cereal crops, one bacterial strain Pseudomonas aurogenosa “NEIST 003” was selected for its antagonistic ability against different rice fungal pathogens under in vitro conditions. The per cent inhibition of mycelial growth of different rice fungal pathogens namely “R. oryzae-sativae, Fusarium moniliforme, Rhizoctonia solani, Curvularia oryzae, Fusarium oxysporium, and Pyricularia grisea by P. aurogenosa “NEIST 003” was 35.11, 21.33, 33.11, 25, 34.22, and 41.67%, respectively. Under greenhouse conditions, P. aurogenosa “NEIST 003” promoted plant growth besides inhibiting rice fungal pathogen R. oryzae'sativae and gave highly significant growth improvement compared to the other treatments for all parameters including shoot height, root length, tiller number, number of leaves, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, moisture content, chlorophyll content, and disease incidence at different days of seedlings infection. P. aurogenosa “NEIST 003” has the ability to promote plant growth and suppressed most of the rice fungal pathogens.