Management of brown spot disease of rice caused by Helminthosporium oryzae (Breda de Haan) in Allahabad agro-climatic conditions

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Date
2020
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Department of plant pathology Naini Agricultural Institute, Faculty of Agriculture, Sam Higginbottom University of Agriculture, Technology and Sciences (Formerly Allahabad Agricultural Institute) Prayagraj-11007 (U.P), India
Abstract
Five indigenous plants of Manipur viz., Flogacanthus thyrsiflorus, Mariandra benghalensis, Millettia pachycarpa, Alliumhookerii and Solanum incanum were screened in-vitro at different concentration i.e., 10%, 15% and 20% against the radial growth of Helminthosporium oryzae, and found maximum per cent inhibition on biomass production in broth media was at 20% concentration in S. incanum (58.58) followed by A. hookerii (44.72). In solid media maximum per cent reduction on radial growth was recorded in S. incanum (53.29) and A. hookerii (44.29) in compared with the control.The in-vivo test of consecutive two cropping seasons (2014-15) and (2015-16), found that maximum reduction in per cent disease incidence (PDI) of H. oryzae was in S. incanum (39.68) followed by A. hookerii (31.36) in compared o other treatments including control. Among the botanicals maximum grain yield were recorded in S. incanum3.37 (t/ha.), followed by A. hookerii (3.27 t/ha.). It was found that all treatments significantly increased yield in compared with the untreated control. Investigation were also carried out to evaluate the efficacy of selected fungicides viz., Thiophanate, Myclobutanil, Carbendazim, Propineb, Propiconazole and bio-agent (Pseudomonas fluorescens) against Helminthosporium oryzae. The in-vitro test results revealed that among the selected fungicides best per cent inhibition on fungal biomass production was recorded in Propiconazole (85.71) followed by Propineb (80) in broth media, in solid media test maximum per cent inhibition on radial growth was recorded in Propiconazole (74.26) followed by Propineb (73.04) over the control. The antagonistic effect of Pseudomonas fluorescens on dual culture test revealed maximum reduction on linear growth of H. oryzae was recorded in cell concentrations (1.37x10⁸)/ml, with (52.23%) reduction over control. The in-vivo trial revealed that maximum reduction of per cent disease incidence (PDI) was in Propiconazole (72.39) followed by Propineb (69.40), Myclobutanil (63.52) and bio-agent Pseudomonas fluorescens (59.58) and least per cent reduction among selected chemical fungicide was recorded in Thiophanate (39.41), however all treatments were found significantly different in compared with the untreated control. It is also observed that selected fungicides and Pseudomonas fluorescens treatment were found to have a significant effect on plant growth parameters being investigated i.e., plant height, flag leaf length and breadth, number of filled grain and the yield parameter in compare with the untreated control. Among the treatments maximum grain yield perunit area was recorded in Propiconazole (5.6 t/ha.), followed by Propineb (5.46 t/ha.), Myclobutanil (4.68 t/ha.), Pseudomonas fluorescens (4.63 t/ha.) and minimum yield among the treatments was recorded in Thiophanate (4.21 t/ha.), however, all treatments were found significantly higher in yield in comparison with the untreated control (3.46 t/ha.). Analysis on the weather data and correlation studies of disease incidence revealed temperature (Tmax), Win speed (WS) and relative humidity (Rhmax) are the key weather factors that influenced the disease incidence of brown spot of rice in the years of studies.
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Ph. D. Thesis
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