In the present study, a total of 92 phosphate solubilizing bacterial strains were isolated from the rhizospheric soil of Zea mays grown in Solan (H.P), India out of which 11 isolates showed more then 5 mm zone of solubilization. These 11 isolates were subjected for quantification of phosphate solubilization in NBRIP broth. From these 11 strains, isolate MZPSB58 showed highest solubilization (621.49 μg P/ml) followed by isolate MZPSB16 (571.24 μg P/ml) whereas, standard strain of Pseudomonas putida showed 547.89 μg P/ml of phosphate solubilization. These 11 isolates were further tested for the production of IAA, ammonia and siderophore and eight, ten and seven isolates were found to produce these compounds respectively. The isolates MZPSB16 and MZPSB58 produced 74.95 μg/ml, 86.39 μg/ml of IAA respectively, which was significantly higher than the standard strain (62.83 μg/ml). Antifungal activity against Fusarium oxysporum and Rhizoctonia solani was observed only in five isolates out of 11. Isolate MZPSB16 showed more zone of inhibition as compared to isolate MZPSB58. These two isolates were also tested for the production of hydrolytic enzymes when MZPSB58 and MZPSB16 were found positive for chitinase and protease activity but standard strain was found negative. The ACC deaminase activity of isolates MZPSB16 and MZPSB58 were tested and MZPSB16 showed 1.14 μm αKB mg−1 h−1 enzyme activity whereas the isolate MZPSB58 showed 1.82 μm αKB mg−1 h−1 enzyme activity. The standard strain also showed 1.02 μm αKB mg−1 h−1 enzyme activity. On the basis of 16S rRNA gene sequencing the isolate MZPSB16 was identified as Bacillus subtilis whereas, isolate MZPSB58 was identified as Pseudomonas putida. These native isolates will be more useful as bio-fertilizer and in biological control.

Phosphate Solubilizing Bacterial Diversity From The Rhizospheric Soils of Sub-Temperate Region of Himachal Pradesh

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, ChathaResults: 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.

https://www.thepharmajournal.com/archives/2019/vol8issue10/PartE/8-9-108-185.pdf

SA Ganie

Papers

Bio-control potential of fluorescent pseudomonads against sheath blight of rice