GURURAJ SUNKAD ¹, AKSHATA GOUR ¹, RANJANA JOSHI ², MEGHANA PATIL ¹

Affiliations
1 Department of Plant Pathology, University of Agricultural Sciences, Raichur-584104, India ., IN
2 Department of Plant Pathology, University of Agricultural Sciences, Raichur-584104, India., IN

Abstract

Rice (Oryza sativa L.), as a cereal grain, is the most widely consumed staple food for a large part of the world’s human population, especially in Asia and Africa. Rice production is often subjected to several biotic and abiotic stresses. Rice sheath blight is one of the most destructive diseases causing economic losses in rice yields and affecting quality worldwide. Twenty soil samples were collected from the rhizosphere of rice crop from different regions of Northern Karnataka. Trichoderma spp. were isolated from the rhizospheric soil samples. The antagonistic potential of Trichoderma spp. was studied using dual culture technique. Among twenty strains of Trichoderma the highest inhibition (>50%) was recorded in nine strains which ranged from 54.20 to 65.10 per cent. Trichoderma harzianum recorded highest seed germination (100%), root length (13.73 cm), shoot length (8.64 cm) and seedling vigour index. In pot culture experiment, the Trichoderma strains significantly improved the growth parameters such as root length, shoot length and number of tillers per plant. Among the different treatments, seed treatment + root dipping + foliar spray with T. harzianum strain was highly effective in increasing the shoot length, root length and seedling vigour index at 30, 60 and 90 days after sowing. This strain was found highly effective in inhibiting the pathogen and promoting the growth of rice plants.

Keywords

Plant growth promotion, rice, sheath blight, Trichoderma strains

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GURURAJ SUNKAD ¹, KHADARBI ¹, RANJANA JOSHI ¹, MEGHANA S. PATIL ¹

Affiliations
1 Department of Pathology, University of Agricultural Sciences, Raichur - 584104, Karnataka, India ., IN

Abstract

Stem and pod rot of groundnut is an economically important soil borne disease caused by Sclerotium rolfsii Sacc. The present study aimed to evaluate the indigenous bacterial bio control agent Pseudomonas fluorescens strains having multiple traits related to bio control and plant growth promoting activity. Healthy rhizospheric soil from groundnut field was collected from different North Karnataka districts. Nineteen strains of P. fluorescens were isolated by serial dilution technique on King’s B medium. The antagonistic potential of nineteen strains was tested against S. rolfsii by using dual culture technique. The per cent inhibition was highly variable among the nineteen strains of P. fluorescens ranging from 2.59 to 75.18 per cent. Maximum mycelial inhibition of S. rolfsii was recorded by the strain PF-2 (75.18%) followed by PF-3 (72.96%), PF-6 (69.62%) and least inhibition was recorded by PF-13 (2.59%). Five superior strains of P. fluorescens showed fluorescens under UV light, yellowish green pigmentation, rod shaped cells under microscope. Five superior strains were subjected for various biochemical tests and all the isolates were positive for biochemical characterization such as Gram staining, endospore production, catalase, starch hydrolysis, urease test, casein hydrolysis and gelatin liquefy action and negative for KOH and in dole test. Further, these strains were subjected for plant growth promoting traits such as HCN production, IAA production, siderophore production and volatile compounds production. Among these, the strainsviz., PF-2 and PF-3 were scored as strong with respect to antagonism and growth promotion. The strainsPF-6, PF-7 and PF-10 were scored as moderate with light brown colour. Among the tested strains of P. fluorescens, the isolates PF-2 and PF-3 were recorded higher production of siderophore, isolates PF-6, PF-7 and PF-10 showed moderate production of siderophore. The strain PF-2 of P. fluorescens showed highest per cent of mycelial inhibition of S. rolfsii indicating higher production of volatile compounds, followed by PF-3 and PF-6. Whereas, the least mycelial inhibition was recorded by the isolate PF-10 indicating less production of volatile compounds.

Keywords

Groundnut, management, Pseudomonas, sclerotium rot

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GURURAJ SUNKAD ¹, MEGHANA S. PATIL  ¹, RANJANA JOSHI ¹

Affiliations
1 Department of Plant Pathology,   University of Agricultural Sciences, Raichur – 584104, Karnataka, IN

Abstract

Chickpea (Cicer arietinum L.) is grown in more than 50 countries. India is the largest chickpea-producing country accounting for 64% of the global chickpea production. However, the production is contrained by the dry root rot disease caused by Rhizoctonia bataticola. Considering this problem, the investigation was carried out to isolate, characterize and the antagonistic potential of indigenous endophytic PGPMs for one of the components in the integrated management of dry root rot of chickpeas in eco-friendly manner. Hence, the isolation of thirty endophytic PGPMs was carried from chickpea by using the spread plate technique. The cultural characters and Gram’s staining reaction confirmed that the endophytic PGPMs isolated from chickpea plant tissues were bacteria. Among thirty bacterial strains, eight showed more than 50% of mycelial inhibition of the pathogen. Out of eight strains, five highly superior strains were selected and subjected for 16S rDNA gene sequencing using the universal primers (16Sr DNA F and 16Sr DNA R), which produced amplified products of size 1500 bp. nBLAST results of 16S rDNA gene sequence revealed that all the endophytic bacterial PGPMs showed homology with genus Bacillus but with different species. The five potential strains namely, BEPGPM-5, BEPGPM-9, BEPGPM-27, BEPGPM-28, and BEPGPM-30 were identified and confirmed as B. tropicus, B. pacificus, B. cereus, B. subtilis, respectively, based on molecular technique.

Keywords

Bacillus cereus, B. pacificus, B. subtilis, B. tropicus, chickpea, dry root rot

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