Vol. 8, Issue 10 (2019)

Aim: The present study was conducted to investigate the biocontrol potential of fluorescent pseudomonads in- vitro and in-vivo responsible for causing sheath blight of rice.

Methodology: Indigenous isolates (20 nos.) of fluorescent pseudomonads, collected from the rhizosphere of basmati paddy fields from different locations of Jammu province, which were further characterized for their bio-control activity against Rhizoctonia solani causing sheath blight of rice under laboratory and glasshouse conditions at Division of Plant Pathology, Faculty of Agriculture, SKUAST- Jammu, Chatha

Results: On the basis of biochemical tests, isolate Fp1, Fp2, Fp4, Fp5, Fp6, Fp7, Fp9, Fp11, Fp17 and Fp18 were able to grow at 4°C and were identified as Pseudomonas fluorescens, whereas, isolate Fp3, Fp8, Fp10, Fp12, Fp13, Fp14, Fp15, Fp16, Fp19 and Fp20 which grew at 41°C and utilized the acetamide were identified as Pseudomonas aeruginosa. Under in vitro conditions, out of ten isolates (Fp1- Fp10), Fp6 showed maximum per cent inhibition (84.09 and 86.66) of mycelial growth of R. solani, followed by Fp1 (81.81and 84.89), whereas, minimum inhibition was observed by Fp8 (43.40 and 64.00) on PDA and NA media, respectively, using dual culture assay. All the isolates reduced the germination of R. solani sclerotia with range of 49.05-90.87% and also enhanced the vigour index of the rice seedlings ranging from 595.05 to 1683.27. In detached leaf assay rice leaves treated with suspension of Fp6 isolate significantly showed minimum lesion length (12.66 mm) with maximum per cent reduction of lesion (81.91%) as compared to untreated control (70.00 mm). The treatment T4 (P. fluorescens) and T8 (P. aeruginosa) (seed soaking + seedling dip +foliar spray) showed disease intensity of 10.94 and 14.06 per cent with 42.19 and 39.07 per cent disease reduction, respectively, as compared to untreated control.

Interpretation: Due to dominance of fluorescent pseudomonads (P. fluorescens and P. aeruginosa) in the rice rhizosphere and diverse mechanism of action, it had the potential for reducing sheath blight incidence of rice caused by R. solani.