Vermicompost enhances performance of plant growth-promoting rhizobacteria in Cicer arietinum rhizosphere against Sclerotium rolfsii

Collar rot of chickpea (Cicer arietinum) is caused by the soil-borne pathogen Sclerotium rolfsii and management of this ubiquitous pathogen is not possible through a single approach. An integrated approach was adopted by using vermicompost and an antagonistic strain of Pseudomonas syringae (PUR46) possessing plant growth-promoting characteristics. Treatments with vermicompost (10%, 25%, and 50% v/v) and PUR46 alone and in combination reduced seedling mortality in chickpea under glasshouse conditions. The combined effect of 25% vermicompost substitution along with seed bacterization with PUR46 was the most effective treatment, which not only increased the availability and uptake of minerals like P, Mn, and Fe in chickpea seedlings, resulting in an increase in plant growth, but also reduced plant mortality. These effects are correlated with improvement in soil physical conditions and enhanced nutritional factors due to vermicompost substitution as well as plant growth promotion and the antagonistic activity of PUR46 against the pathogen. Dual cultures of PUR46 with the S. rolfsii isolate revealed a high degree of antagonism by PUR46 against the pathogen. Performance of PUR46 was enhanced in the presence of 25% vermicompost compared with its application alone and therefore this combination may be a useful tool to manage S. rolfsii under field conditions. (C) 2007 Elsevier Ltd. All rights reserved.