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SCREENING OF LOCAL RHIZOBIAL ISOLATES FOR PLANT GROWTH PROMOTION Siderophore production Siderophores were detected quantitatively by CAS Shuttle Assay (Schwyn and Neilands, 1987). 0.5% of cell free culture supernatant was added to 0.5% CAS (Chrome Azurol Sulphate) assay solution and absorbance was measured at 630nm against a reference consisting of 0.5ml uninoculated broth and 0.5ml CAS reagent. Siderophore content in the aliquot was calculated by using the following formula: % siderophore units = Where, A r = Absorbance of reference at 630nm A s = Absorbance of sample at 630nm. Antagonistic activity against fungal pathogens Antagonism against the fungal pathogens was performed by dual culture assay (Skidmore and Dickinson, 1976). One loopful of bacterial suspension was streaked on potato dextrose agar plate at one end, which was pre-inoculated with 5days old, 5mm mycelial discs of test pathogen at the other end. Control plate was maintained by placing only pathogen mycelial disc on the plate without bacteria. The assay plates were incubated at 28 1 0 C for 5 days and observations were made on inhibition of mycelial growth of the test pathogens. For each bacterial isolate three replications were maintained with suitable controls. The per cent growth inhibition over control was calculated by using the formula: Percent Inhibition = Growth of Pathogen in control (mm)- Growth of Pathogen in treatment (mm) Growth of Pathogen in control (mm) (In this the percent inhibition in control was taken as zero percent). RESULTS AND DISCUSSION Isolation of Rhizobium isolates X 100 Fifteen soil samples were collected from different places of Rangareddy district for the isolation of Rhizobium isolates. The soil samples were mainly collected from the rhizosphere of groundnut and redgram crop plants. All the soil samples were inoculated on the YEMA (Yeast Extract Mannitol Agar), based on the colony morphology and cultural characteristics of the isolates on the above media, about ten colonies from above plates were selected, purified on respective media and subjected to gram staining for morphological examination. The isolates were named according to village, crop and cultural characters as SFGR to CFGR. All the isolates were gram-ve, single isolated rods with gummy white, round, non spreading, smooth, raised, translucent mucoid colony and no pigmentation. Kumar et al., (2010) isolated root nodulating Sinorhizobium fredii KCC5 from nodules of Cajanus cajan and disease suppressive soil of tomato rhizosphere, respectively and studied their physiological and biochemical characterization which confirms the purity of these isolates. Joseph et al., (2007) isolated a total of one hundred and fifty isolates from different soils of chickpea from the vicinity of Allahabad and among them thirty five isolates were identified as Rhizobium on the basis of morphological and biochemical characterization. Deka and Azad (2006) isolated one hundred and fifty seven isolates of Rhizobium from six pulse crops Cowpea, Green gram, Black gram, Pigeon pea, Soybean, Groundnut and studied their physiological and biochemical characterization which confirms the purity of these isolates. Screening of pure Rhizobium isolates for Phosphate solubilization, production of indole acetic acid, hydrogen cyanide and siderophores All the ten Rhizobium isolates showed zone of phosphate solubilization activity on Pikovskya’s medium. Out of ten, SFGR showed highest zone of 16mm with 60% Solubilization Efficiency (SE), followed by AGR, KRR and CFGR which showed 14mm zone with 40% S.E. Remaining isolates showed SE of 20% with 12mm of solubilization zone. All the Rhizobium isolates were identified as IAA producers, of which SFRR was found to be strong. Two isolates (DGR and CFGR) produced IAA in fewer amounts, while the remaining showed moderate production of IAA. In case of HCN production, all the isolates showed positive results, of which AGR and KRR showed strong production. SFGR, SFRR, ARR, DRR, KGR, SBGR showed moderate production, while other two (DGR and CFGR) showed weak production. 47
SARVANI et al Seven of the isolates showed positive results for siderophore production. Kumar et al. (2010) screened Sinorhizobium fredii KCC5 from Cajanus cajan and reported that the strain produced IAA, solubilized phosphorus and siderophore production. Verma et al., (2010) evaluated Rhizobium spp. for in vitro PGP properties and concluded that the bacterial strain was found to be positive for IAA and phosphate solubilization. Joseph et al., (2007) isolated thirty five Rhizobium spp. from the rhizosphere soils of chickpea crop plants and screened in vitro for their plant growth promoting characteristics. Results revealed that 85.7% of Rhizobium isolates showed IAA production. Similarly, Chandra et al., (2007) isolated Mesorhizobium loti MP6, from root nodules of Mimosa pudica which induced growth and yield of Brassica campestris through plant growth promoting attributes. The isolate MP6 showed production of IAA, HCN, phosphate solubilization and siderophore production. Nabi et al. (2005) identified ten strains of Rhizobium meliloti from the root nodules of Fenugreek (Trigonella foenum- graceum) and studied for PGP properties. They concluded that different strains of Rhizobium meliloti exhibited the properties of IAA, HCN and siderophore production. In the present study, the rhizobial isolates can be graded in the order SFGR>KRR=AGR>SFRR, based on efficiency. Antagonistic activity against fungal pathogens All the ten isolates inhibited Rhizoctonia solani except DGR, of which SBGR showed highest % inhibition with 12.6mm zone, followed by DRGR and CFGR with 44% inhibition and 11mm zone. Least % inhibition was shown by AGR (39.2%) with 5.6mm zone. Six of the ten Rhizobium isolates exhibited antagonistic activity against Sclerotium rolfsii viz., KRR (50.7%), SBGR (49.2%), SFGR (48%), AGR (48.8%), DGR (45.1%) and SFRR (38.8%). All the Rhizobium isolates showed potential in the biocontrol of Fusarium solani. Among which AGR recorded maximum inhibition of 44.6% with 25.3mm of inhibition zone. The isolates SFGR, SFRR and CFGR were on par with AGR. DGR showed least percent inhibition of 32.3% (14mm zone) inhibition. These findings were found to be similar with those of Shaban and El-Bramaway (2011) who studied the biological control of damping off and root rot causing fungi (Fusarium oxysporum, F. solani, Macrophomina phaseolina, Rhizoctonia solani and Sclerotium rolfsii) with antagonistic microorganism (Rhizobium spp and Trichoderma sp). They revealed that combined effect of both Rhizobium spp and Trichoderma sp was found to be beneficial in controlling the fungal diseases of legume crops. Akthar et al., (2010), reported that combined application of Bacillus pumilus and Pseudomonas alcaligenes with Rhizobium spp. resulted in the greatest increase in the plant growth, number of pods, nodulation and root colonization by rhizobacteria, in Lentil. Yuan et al., (2008) isolated Sinorhizobium freudii (L 396) from soybean root nodule and evaluated antagonistic activity against Heterodera glycines and pathogens of Soyabean (Glycine max) root rot. Hatching inhibition rate of cysts treated with the bacteria suspension at 7 days was 82.9%. L396 displayed antifungal activity to two soyabean root rot pathogens, especially to Fusarium solani, with 4 mm inhibition zone. In the present study, out of ten Rhizobium isolates tested, all the isolates exhibited inhibition potential against Rhizoctonia solani (Except DGR) and Fusarium solani. Only six of the isolates showed inhibition potential against Sclerotium rolfsii. The isolates that showed maximum inhibition potential against Rhizoctonia solani were also inhibitory to Sclerotium rolfsii and Fusarium solani, based on percent inhibition and vice-versa. Some of the isolates that showed inhibition to one pathogen were not inhibitory to the other two pathogens. All the ten isolates showed HCN production, whereas seven of the isolates produced siderophores. It can be inferred that the Rhizobium isolates SFGR, SBGR, AGR and KRR could be considered for their antagonistic activity against the three soil borne pathogens. Though KRR showed higher siderophore and HCN production, it showed better inhibition to Sclerotium rolfsii. Comparing the antagonistic activity against these pathogens and production of siderophores and HCN, the effectiveness of these isolates is in the order: SBGR> AGR> SFGR> KRR. 48
Page 2 and 3: CONTENTS PART I : PLANT SCIENCE Ads
Page 4 and 5: J.Res. ANGRAU 41(2) 1-10, 2013 ADSO
Page 6 and 7: ADSORPTION DESORPTION OF PENDIMETHA
Page 14 and 15: J.Res. ANGRAU 41(2) 11-15, 2013 STU
Page 16 and 17: STUDIES ON THE EFFECT OF PLANT GROW
Page 18 and 19: STUDIES ON THE EFFECT OF PLANT GROW
Page 20 and 21: PERFORMANCE OF DRUM SEEDER IN DIREC
Page 22 and 23: PERFORMANCE OF DRUM SEEDER IN DIREC
Page 24 and 25: J.Res. ANGRAU 41(2) 21-25, 2013 EFF
Page 26 and 27: EFFECT OF GRADED LEVELS AND TIME OF
Page 28 and 29: EFFECT OF GRADED LEVELS AND TIME OF
Page 30 and 31: ASSESSMENT OF GENETIC DIVERSITY IN
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Page 38 and 39: ESTIMATION OF HETEROSIS FOR YIELD A
Page 46 and 47: INTEGRATED EFFECT OF ORGANIC MANURE
Page 48 and 49: INTEGRATED EFFECT OF ORGANIC MANURE
Page 52 and 53: SCREENING OF LOCAL RHIZOBIAL ISOLAT
Page 54 and 55: SCREENING OF LOCAL RHIZOBIAL ISOLAT
Page 56 and 57: CHARACTERIZATION AND CLASSIFICATION
Page 62 and 63: J.Res. ANGRAU 41(2) 59-67, 2013 IDE
Page 64 and 65: IDENTIFICATION OF SUPERIOR PARENTS
Page 72 and 73: EFFECT OF FRONT LINE DEMONSTRATIONS
Page 78 and 79: EFFECT OF FEEDING COMPLETE FEED CON
Page 80 and 81: EFFECT OF FEEDING COMPLETE FEED CON
Page 82 and 83: EFFICACY OF CONTROLLED INTERNAL DRU
Page 90 and 91: EFFECT OF NSP ENZYMES AND PREBIOTIC
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HAEMATOLOGICAL AND BIOCHEMICAL PROF
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HAEMATOLOGICAL AND BIOCHEMICAL PROF
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INDIAN BREAD MAKING TOOLS - CONSUME
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Research Notes J.Res. ANGRAU 41(2)
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CROP COEFFICIENTS FOR DRIP AND CHEC
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STUDY ON THE EFFECT OF IRRADIATION
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EVALUATION OF DEFOLIANTS ON MUNGBEA
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YIELD, NUTRIENT UPTAKE AND ECONOMIC
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YIELD, NUTRIENT UPTAKE AND ECONOMIC
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NANO FOOD COLOURS FOR PRODUCT FORMU
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EFFECT OF ORGANIC FERTILISERS ON GR
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EFFECT OF ORGANIC FERTILISERS ON GR
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NUTRIENT UPTAKE OF MICROSPRINKLER I
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EFFECT OF SYNERGIST, TRIPHENYL PHOS
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EFFECT OF SYNERGIST, TRIPHENYL PHOS
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EFFECT OF HARVESTING STAGES AND DRY
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RESPONSE OF AEROBIC RICE TO IRRIGAT
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RESPONSE OF AEROBIC RICE TO IRRIGAT
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DRIP IRRIGATION SCHEDULE FOR CASTOR
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CHARACTER ASSOCIATION AND PATH COEF
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CHARACTER ASSOCIATION AND PATH COEF
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Statement about ownership and other
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GUIDELINES FOR THE PREPARATION OF M
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ESSENTIAL REQUIREMENTS FOR CONSIDER
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