National Academy of Agricultural Sciences (NAAS)
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PRINT ISSN : 2319-7692 Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com / submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
Onion (Allium cepa L.) is one of the most important commercial vegetable crops which have significant nutritional value to the human diet besides possessing medicinal properties. It is affected by various diseases among which soft rot incited by Pectobacterium carotovorum subsp carotovorum (Pcc) is an economically important disease in the field and storage. In the present study, survey carried out in Madurai, Perambalur and Salem districts of Tamil Nadu revealed that the maximum incidence of onion soft rot (63.25 %) was noticed in Muthampatti of Salem district of Tamil Nadu whereas lowest incidence (16.39 %) was noticed in Arasakulam of Madurai district. Ten bacterial isolates were isolated from symptomatic onion which produced grey and convex slimy colonies on nutrient agar medium. Biochemical characterization revealed that all the isolates were tested positive for potato soft rot test, catalase production, OF test, gelatin liquefaction, KOH solubility, methyl red test, and growth in 5% NaCl and negative for gram reaction, oxidase and gas formation. In vitro pathogenicity tests showed that, the isolate PCC 6 was found to be high virulent which developed typical water-soaked symptoms in onion bulbs after 2 days and soft rot symptoms were expressed on 4 days after inoculation. The presence of deep pits and cavities zone in agar plates confirmed that all the isolates were Pectobacterium spp. Based on the phenotypic, and biochemical characterization, the isolates were identiï¬ed as Pectobacterium carotovorum subsp. carotovorum.
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