Bio-effective disease control and plant growth promotion in lentil by two pesticide degrading strains of Bacillus sp.

Abstract

Antagonistic bacteria are common soil inhabitants with potential to control several soil-borne diseases of various crops. In this study, two methomyl degrading Bacillus sp. were screened for their antagonistic potential against soil borne pathogen identified as Alternaria sp. which causes leaf spot and blight disease in lentil. Both the strains produced non-volatile and volatile organic compounds, extracellular enzymes, siderophore, indole acetic acid and solubilized phosphate which ascribed to the mechanism of bio-control and plant growth promotion. These bacterial strains produced indole acetic acid, chitinase and solubilized phosphate even in presence of pesticides (namely methomyl, carbendazim and imidacloprid). The production of chitinase increased by 51–140% in presence of different tested pesticides by the bacterial strains. However, phosphate solublization was only increased up to 79% in B. cereus and 87% in B. safensis in presence of methomyl. Both strains promoted plant growth and suppressed leaf spot and the incidence of blight in lentil plants under controlled conditions in green house. Application of B. cereus and B. safensis isolates to sterile rhizospheric soil increased the dry weight of plants by 40.8% and 43.2%, respectively as compared to control. In similar set of experiments the disease incidence was reduced by 67.7–81.6% in B. cereus and 57.2–78.8% in B. safensis in sterile condition and by 51.4–76.5% and 48.6–63.4%, respectively in non-sterile condition. The present investigation shows both B. cereus and B. safensis as potential plant growth promoting rhizobacteria that can be exploited as efficient bio-control organisms against soil borne plant pathogens as well as can be applied in plant growth enhancement even in pesticide infested soil.