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Harikrishnan H.,Madurai Kamaraj University | Shanmugaiah V.,Madurai Kamaraj University | Balasubramanian N.,New University of Lisbon | Sharma M.P.,Directorate of Soybean Research DSR Indore ICAR | Kotchoni S.O.,Rutgers University
World Journal of Microbiology and Biotechnology | Year: 2014

A total of 132 actinomycetes was isolated from different rice rhizosphere soils of Tamil Nadu, India, among which 57 showed antagonistic activity towards Rhizoctonia solani, which is sheath blight (ShB) pathogen of rice and other fungal pathogens such as Macrophomina phaseolina, Fusarium oxysporum, Fusarium udum and Alternaria alternata with a variable zone of inhibition. Potential actinomycete strain VSMGT1014 was identified as Streptomyces aurantiogriseus VSMGT1014 based on the morphological, physiological, biochemical and 16S rRNA sequence analysis. The strain VSMGT1014 produced lytic enzymes, secondary metabolites, siderophore, volatile substance and indole acetic acid. Crude metabolites of VSMGT1014 showed activity against R. solani at 5 µg ml−1; however, the prominent inhibition zone was observed from 40 to 100 µg ml−1. Reduced lesion heights observed in culture, cells-free filtrate, crude metabolites and carbendazim on challenge with pathogen in the detached leaf assay. The high content screening test clearly indicated denucleation of R. solani at 5 µg ml−1 treatment of crude metabolite and carbendazim respectively. The results conclude that strain VSMGT1014 was found to be a potential candidate for the control of ShB of rice as a bio fungicide. © 2014, Springer Science+Business Media Dordrecht. Source

Sharma M.P.,Tata Energy Research Institute | Sharma M.P.,Directorate of Soybean Research DSR Indore ICAR | Adholeya A.,Tata Energy Research Institute
Experimental Agriculture | Year: 2011

The production potential of three arbuscular mycorrhizal fungi (AMF), AM-1004 (Glomus intraradices), AM-1209 (mixed indigenous AMF) and AM-1207 (Mycorise, commercial inocula), were examined separately in three fractions/forms (root-based, soil-based and mixture of roots + soil) at 40, 60, 80 and 105 days in raised beds. The beds were amended with organic matter to develop regression equations for predicting optimal AM production vis-a-vis time required for particular inocula using infectious propagules (IP) as the independent variable. The IP production observed in the system was found to vary among the different inocula used. AM-1004 and AM-1207 produced significantly higher propagule counts in root or soil-based samples and a mixture of both at 105 days as compared to AM-1209. Based on two-way ANOVA, irrespective of time, AM-1004 (root/soil-based) produced a significantly larger number of propagules, whereas propagules in the crude inoculum (roots + soil) of all three inocula were not significantly different. On the other hand, irrespective of AMF, significantly more propagules (in all forms) were observed at 105 days. Similarly, irrespective of time, AM-1004 produced significantly higher root colonization (MCP, mycorrhizal colonization percentage) in all three forms (roots: 65.95%; soil: 24.32; soil + roots: 58.03%). The MCP in roots was increased significantly with time of multiplication. However, there was not much improvement in the MCP of soil or in soil + roots fractions beyond 80 days. Further, prediction of the number of IP for the three AM inocula was mathematically derived separately from the Mitscherlish-Bray equation (Y = a-b*exp (-cD). Based on the maximum yield of propagules of the three inocula observed and fitted into equations, root-based AM-1004 and AM-1209 inocula were found to be more efficient in producing propagules in 65 days as compared to AM-1207, which produced propagules in 76 days. While comparing the overall combinations, AM-1004 and AM-1209 inocula used either as roots, soil or a mixture of both and have greater potential in producing more propagules in the shortest span of time. While taking into account the predicted values of AM-1209 crude inoculum, about 12 IP g?1 substrate can be achieved in 72 days. Therefore, if a farmer uses crude inocula (having zero time IP of about 0.8/g substrate) of AM 1209, a total production of about 12.12 million IP/m3 can be achieved in 72 days. These can be used for on-farm production. © Cambridge University Press 2011. Source

Manoharan P.T.,Vivekananda College | Shanmugaiah V.,University of Madras | Balasubramanian N.,University of Madras | Gomathinayagam S.,University of Madras | And 2 more authors.
European Journal of Soil Biology | Year: 2010

The present study investigated the effects of arbuscular mycorrhizal (AM) fungus, Glomus mosseae on the growth and physiology state of Erythrina variegata Linn, grown in sandy loam soil with four water stress levels viz. -0.06 MPa (well watered/control), -1.20 MPa (mild), -2.20 MPa (moderate) and -3.20 MPa (severe) in a completely randomized design. Plants were harvested after 90 days (60 days after stress induction) of growth. Growth parameters (root &, shoot, dry weight and, leaf area); physiological parameters (chlorophyll content, carotenoids, soluble starch, sugar, protein and proline in shoots); and microbiological parameter (percentage of mycorrhizal infection) were determined. AM fungal plants had significantly higher plant biomass, higher chlorophyll content (chlorophyll a and b), carotenoids and protein content in shoots than non-AM-plants. The AM-inoculation in stressed plants significantly declined the soluble sugar and starch in shoots. Moreover, AM-inoculation also reduced the proline accumulation in shoots and the reduction was significant when plants were severely stressed (-3.2 MPa). Mycorrhizal colonization in roots of E. variegata depressed significantly due to increased water stress. However, the AM colonization did not decline below 11% and enabled the plants to maintain osmotic adjustments and enhanced the plants tolerance against water stress. © 2010 Elsevier Masson SAS. All rights reserved. Source

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