BACTERIAL ANTAGONISTS FROM USED ROCKWOOL SOILLESS SUBSTRATES SUPPRESS FUSARIUM WILT OF TOMATO

K. Srinivasan, G. Gilardi, A. Garibaldi , M.L. Gullino

Abstract


Five bacterial strains (FC-6B, FC-7B, FC-8B, FC-9B and FC-24B) isolated from used rockwool soilless substrates were identified using 16S ribosomal DNA (16S rDNA) sequence analysis as belonging to the Pseudomonas genus. Seven glasshouse trials were conducted in order to evaluate the efficacy of these bacteria strains (Pseudomonas putida FC-6B, Pseudomonas sp. FC-7B, Pseudomonas putida FC-8B, Pseudomonas sp. FC-9B and Pseudomonas sp. FC-24B) together with Achromobacter sp. AM1 and Serratia sp. DM1 obtained from suppressive soil, against Fusarium wilt of tomato. Two commercial bioproducts, Trichoderma harzianum T22 (RootShield) and Pseudomonas chlororaphis MA 342 (Cedomon) were also evaluated. Different treatment strategies including soil application (107 and 108 cfu ml-1) were adopted in different glasshouse trials (Trial I to VI) to test the efficacy of the bacterial strains against Fusarium wilt. Root dipping was used in Trial VII (108 and 109 cfu ml-1). The lowest disease incidence (3.3) was recorded with a single application of P. putida FC-6B at 108 cfu ml-1. Similar results were obtained with the same bacteria when the concentration was decreased to 107 cfu ml-1 but an increasing number of applications was required. The highest plant biomass (50.3 g/plant) was recorded in the P. putida FC-8B treatment (Trial III). In conclusion, the current study showed the potential biocontrol activity of bacterial strains FC-6B, FC-7B, FC-8B, FC-9B and FC-24B isolated from re-used rockwool soilless substrates against Fusarium wilt disease, and the growth promoting activity of these strains on tomato plants.

Keywords


Biological control; suppressive soil; Fusarium oxysporum f. sp. lycopersici; Pseudomonas spp

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DOI: http://dx.doi.org/10.4454/jpp.v91i1.635

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