Evaluation of Siderophore Production and Antimicrobial Activity by Fluorescent Pseudomonas Diversity Associated with Rhizosphere of Apple and Pear

Replant problem is very serious problem which suppresses growth and yield of apple and pear in all major fruit growing areas of the world. Fluorescent Pseudomonas has potential to synthesize different secondary metabolites with diverse PGPR activities which enhance soil fertility and promote plant growth. Under this study, twenty-six Pseudomonas strains were isolated from the rhizosphere of apple and pear plants from their normal and replant sites. All the isolates were positive for catalase, oxidase, denitrification test, ledthinase test and tween 80 hydrolysis. They were further screened for antifungal and siderophore production. Maximum siderophore production was recorded in isolates AN-l-UHF, AN-3-UHF, PN-7-UHF and PN-13-UHF whereas, maximum antifungal activity against Dematophora sp., Fusarium oxysporum, Alternaria sp. and Pythium sp. was recorded in isolates AN-l-UHF, AN-3-UHF and PN-13-UHF. It was found that Pseudomonas sp. isolated from the replant sites showed comparatively less siderophore and antifungal activities. These potential isolates could be further used as biocontrol agents against various fungal pathogens in apple and pear orchards.

AN-l-UHF, AN-3-UHF, PN-7-UHF and PN-13-UHF isolates showed maximum siderophore and antifungal activities.

Replant rhizosphere soil isolates showed greater activities than replant rhizophere soil isolate.