Development of biocontrol agent against phytopathogenic fungi of tomato (Lycopersicon esculentum Mill.) crop.
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Date
2020-07
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CCSHAU, Hisar
Abstract
In the present study, seventy-eight bacterial isolates were retrieved from the tomato rhizosphere soil and screened for their antagonistic activity against Fusarium oxysporum f. sp. lycopersici, Alternaria solani and Rhizoctonia solani under in vitro conditions. Thirteen isolates, NAU5, NAU10, NAU13, NAU20, NAU21, NAU23, NAU29, NAU32, NAU36, NAA59, NAA60, KBA43 and KBA44 showed broad inhibition zones against A. solani measuring more than 20 mm. Six isolates, NAU19, NAU20, NAU23, NAU24, NAU27 and NAU30 resulted in broad inhibition zones against F. oxysporum f. sp. lycopersici measuring 10.1-20 mm. Six isolates, NAU20, NAU30, NAU35, LBV58, NAV66 and NAV73 resulted in broad inhibition zones against R. solani measuring 15.1-25 mm. Among the retrieved 78 isolates, 28% of rhizobacteria produced high amount of IAA and seven isolates, NAU4, NAU5, NAU10, NAU20, NAU28, KBA43 andKBV47 produced maximum IAA. The amount of IAA production by different isolates varied from 3.62μg/ml (NAV69) to 26.96μg/ml (NAU5). Among 78 isolates tested for chitinase assay, two isolates, NAU13 and NAV68 showed maximum activity. Out of 78 isolates, siderophore production was observed in 42% of retrieved bacteria and five isolates, NAU19, KBV45, KBV46, LBV56 and NAV75 produced maximum orange halo zone. HCN was produced by 10% of isolates and highest HCN was observed by 6 isolates, NAU4, NAU6, NAU20, NAU29, NAU41 and NAA59, qualitatively. Seven isolates, NAU5, NAU20, NAU30, NAU35, NAA59, NAV68 and NAV75 were selected and total of 27 treatments were prepared on the basis of antagonistic and plant growth promoting attributes tested in vitro for further evaluating under pot house conditions. Isolate NAU5 showed maximum shoot length, shoot weight, root weight, fruit yield and disease control (100%) against F. oxysporum f. sp. lycopesici. Isolate NAV75 showed maximum shoot length, shoot weight, root weight, fruit yield and disease control (87%) against A. solani. Isolate NAU35 showed maximum shoot length, shoot weight, root weight, fruit yield and disease control (100%) against R. solani. Irrespective of the fungi, isolate NAU5 showed biocontrol activity against all the three phytopathogens. The seven promising isolates showed the PGPR activities in the order NAV75> NAV68> NAA59> NAU5> NAU35> NAU20> NAU30 irrespective of the fungi in pot house studies. The isolates NAU5 against all the three fungi, NAU35 against R. solani and NAV75 against A. solani can be further tested on the tomato fields as potent biocontrol agents. On the basis of biochemical characterization isolate NAU5 was found to belong to Alcaligenes, NAU35 to Bacillus and NAV75 to Burkholderia genus.