Annals of Plant Protection Sciences

A pot study was carried out to assess the effect of chitin degrading bacteria, Pseudomonas spp. strain NS-1 and Bacillus spp. strain NS-22, on soil microbiological activities in the rhizosphere of pathogen (Fusarium udum) challenged pigeon pea crop. Soil microbial activities in terms of fluorescein diacetate hydrolysis (FDA), dehydrogenase, soil phosphatase and microbial biomass carbon (MBC) and population count of Fusarium pathogen was measured. Highest FDA hydrolysis (3.89 μg fluorescein released g⁻¹ soil hr⁻¹), soil phosphatase (0.177 μg pNP released g⁻¹ soil hr⁻¹), and dehydrogenase activity (8.94 μg TPF formed g⁻¹ soil hr⁻¹) were found in Pseudomonas spp. strain NS-1 treated treatment (T₄), while lowest FDA hydrolysis and dehydrogenase activity were observed in T₃ treatment (Fusarium udum only). Soil microbial biomass carbon value ranged from 36.28–74.34 g/kg⁻¹ soil and was found maximum in Bacillus spp. strain NS-22 + Fusarium udum treatment. Population count of Fusarium was estimated on selective Fusarium agar (SFA) media and it was found in the range of 1.2 to 5.7 × 10⁴ cfu g⁻¹ soil. Drastic reduction in F. udum population was observed at 30 DAS in T₄ pot treatment where seeds were sown after bacterization with Pseudomonas spp. strain NS-1 followed by treatment T₅. These rhizospheric bacteria (Pseudomonas spp. strain NS-1 & Bacillus spp. strain NS-22) revealed their potential as enhancer of soil microbial activities besides possessing biocontrol potential against Fusarium udum pathogen and plant growth promotion activities.