eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2017-03-25 14 1 319 328 10.13005/bbra/2449 21552 article Stuti Sah 1 Manvika Sahgal 2 Rajni Singh 1 Amity Institute of Microbial Biotechnology, Amity University, Sector 125, Noida, UP, India. Department of Microbiology, CBSH, G. B. Pant University of Agriculture and Technology, Pantnagar, India. Insoluble iron present in soil severely restricts its bioavailability for plant growth. Microorganisms present in the rhizosphere release siderophore to make it available to the plants. Among others, fluorescent pseudomonads are known to exert extensive biocontrol action against soil and root borne phytopathogens through release of siderophores. A total of 172 rhizobacterial isolates were obtained from two different ecosystems viz. forests and agricultural soils, among these 34 were found to produce siderophore with an apparent decrease in siderophore production when supplemented with 20 µM iron. With the aim of utilizing siderophore production as an antagonist against Fusarium oxysporium, isolates, four Pseudomonas isolates namely RSP7 (KR051487), RSP8 (KR051488), RSP3 (KR051489) and RSP5 (KR051490) were selected. Paired t-test analysis resulted in showing antagonism of RSP5 as 48.5% on plate, and the paired t-test value as 14with a significance of P< 0.01. RSP showed an antagonism of 20% on plate with t value of 31.1 and P< 0.01. Paired t-test analysis proved a highly significant antagonism with isolate RSP7 (t = 37.37, P < 0.001). The results among the four isolates are comparable with RSP3 as best enhancer and antagonist followed by RSP5 > RSP7 > RSP8. Siderophore mediated antagonism when iron ≤ 20 µM and maximum shoot and root length and dry weight were observed with Pseudomonas as inoculants suggesting application of siderophore producing plant growth promoting rhizobacterial strains in crop productivity. https://www.biotech-asia.org/vol14no1/concomitant-ability-of-siderophore-against-iron-paucity-and-fusarium-wilt-in-lycopersicon-esculentum/ Antagonism Biocontrol; ; Fusarium wilt; Siderophore PGPR;