POTENTIAL OF RHIZOSPHERIC PSEUDOMONAS STRAINS TO MANAGE FUSARIUM WILT OF TOMATO

Abstract

Fusarium wilt induced by Fusarium oxysporum f. sp. lycopersici (FOL) has hampered tomato production worldwide. The present research work was conducted at the Institute of Agricultural Sciences, University of Punjab, Qauid-e-Azam Campus, Lahore, Pakistan during the year 2013-14 to search for a biological control strategy to combat this disease. For this purpose indigenous non-pathogenic rhizospheric isolates of Pseudomonas spp. were collected to test their potential to induce resistance in tomato against Fusarium wilt. On preliminary grounds 31 isolates of Pseudomonas spp. were tested for in vitro antibiosis. Eight isolates that efficiently inhibited the growth of F. oxysporum were selected for further experimentation. Greenhouse study revealed that two bacterial isolates i.e. PM12 and PM29 significantly reduced disease index ≥ 60% in two Fusarium wilt susceptible tomato varieties viz: Nagina and Rio- Grande. In addition these isolates resulted in higher accumulation of defense related enzymes and phenolic compounds in tomato plants. During the two growing seasons of 2013 and 2014, sugarcane pressmud based formulations were developed for field evaluations. Combined application of PM12 and PM29 gave the lowest disease index (18.17%) as compared to the pathogen control. Identification based on amplification of ITS region revealed PM12 and PM29 as P. aeruginosa and P. putida. Results clearly highlights the significance of Pseudomonas strains in suppression of F. oxysporum and promoting plant growth thus indicating their possible use for the management of Fusarium wilt in tomato cultivation.