Microbes assisted management of bacterial wilt of brinjal in pesticide contaminated soil

Abstract

Abstract Growing brinjal (Solanum melongena L.) in a soil polluted with organophosphorus pesticide (OP) residues coupled with an additional threat of wilt disease caused by Ralstonia solanacearum (Rs), pose a formidable management challenge for residue free crop production . Our study aimed at identifying efficient OP-degrading bacteria (OPDB) and their compatibility with microbial bio-control agents (MBCA) for twin objective of microbial degradation of OP -residues and reduction in incidence of bacterial wilt of brinjal in OP- contaminated soil. As many, ten bacterial isolates showing OP- degrading potential were recovered through colony growth in mineral salt (MS) -medium treated with 25 ppm chlorpyriphos. Efficient isolates displaying growth up to 700ppm chlorpyriphos were further screened for OP-degradation, leading to identification of two most efficient OPDB, Acromobacter marplatensis [MW397524] (Am) and Pseudomonas azotoformans [MW397525] (Pa). These two isolates having in vitro compatibility with each other, showed further compatibility with two most widely used MBCA, viz., Pseudomonas flourescens [KT258013] (Pf) and Trichoderma harzianum [ON364138] (Th), facilitating the development of consortium having extended functional corridor. The response of combination of OPDB + MBCA(Am +Pa + Pf + Th) showed 80% lower percent wilt incidence (PWI), 2.8 times higher fruit yield ofbrinjal, and 15-25% lower OP-residues over un-inoculated control treatment. Our studies, hence, put forward a strong unified delivery mechanism of OPDB and MBCA as a part of green technology for chemical residue -free vegetable production in contaminated soils.