Biocontrol potential of indigenous fluorescent pseudomonads against banded leaf and sheath blight of maize incited by Rhizoctonia solani f.sp. sasakii
| dc.contributor.advisor | Sahgal, Manvika | |
| dc.contributor.author | Brindhaa, N.T. | |
| dc.date.accessioned | 2019-08-27T06:58:39Z | |
| dc.date.available | 2019-08-27T06:58:39Z | |
| dc.date.issued | 2019-07 | |
| dc.description.abstract | Maize, the third most important cereal crop in the world is exposed to various abiotic and biotic stresses resulting in huge yield loss. The yield loss associated with fungal pathogens is estimated to be more than 10%. Of which, banded leaf and sheath blight (BL&SB) caused by Rhizoctonia solani f.sp.sasakii alone leads to 11-40 % yield loss. The aim of the study was to evaluate biocontrol potential of 22 indigenous (AS1-AS22) fluorescent pseudomonads (FLPs) (18 from Almora & 4 from Pithoragarh districts of Uttarakhand) against BL&SB. All the bacterial isolates were screened for in vitro antagonism against R.solani f.sp.sasakii coupled with hydrolytic enzyme production and plant growth promoting (PGP) traits. Out of these, two strains AS19 and AS21 showed the highest percent mycelial inhibition. The % mycelial inhibition with whole cell culture of AS19 and AS21 was 57.04 % & 54.07 respectively, whereas with cell free supernatant it was 67.41% & 65.74% respectively. Further, scanning electron micrographs revealed that hyphal cell wall at interaction zone of fungal mycelium with AS19 and AS21 was damaged. Both the FLP strains also inhibited the formation and germination of sclerotia in R.solani f.sp.sasakii and exhibited PGP traits like production of rhamnolipid, HCN, siderophore, IAA, ammonia and zinc and phosphate solubilization. They produced protease, chitinase, catalase, oxidase, gelatinase and H2S. Bacterial strains AS19 and AS21 were identified as Pseudomonas spp. through 16S rDNA sequence analysis with % similarity of 89.27 % and 86.62% respectively. The biocontrol efficacy of strains was evaluated in vivo through pot trial. The strains AS19 and AS21 significantly reduced the BL&SB disease incidence (DI). The reduction in DI ranged between 25-38.33%. Combined results of detached leaf assay and pot trial revealed that induced systemic resistance (ISR) was the mechanism of disease control. Foliar spray of two antagonistic isolates 48 hr before pathogen inoculation induced ISR and reduced the DI by half. The two strains AS19 and AS21 exhibited broad spectrum in vitro antifungal activity against Alternaria triticina, Bipolaris sorokiniana, Rhizoctonia maydis and Fusarium oxysporum f.sp.lentis. Future studies should focus on identification of the bacterial metabolite responsible for induced systemic resistance. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810124084 | |
| dc.keywords | biological control, Pseudomonas, leaves, blight, maize, Rhizoctonia solani f.sp. sasakii | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 135 | en_US |
| dc.publisher | G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand) | en_US |
| dc.research.problem | Maize | en_US |
| dc.sub | Microbiology | en_US |
| dc.subject | null | en_US |
| dc.theme | Biological Control | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | Biocontrol potential of indigenous fluorescent pseudomonads against banded leaf and sheath blight of maize incited by Rhizoctonia solani f.sp. sasakii | en_US |
| dc.type | Thesis | en_US |