VARIABILITY AMONG DIFFERENT ISOLATES OF Xanthomonas axonopodis pv. malvacearum
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Date
2019-08-07
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Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra.
Abstract
Bacterial blight disease of cotton caused by Xanthomonas axonopodis pv. malvacearum is one of the most destructive disease of cotton inflicting considerable quantitative and qualitative losses. Mostly the disease occurred on leaves, stems. Considering the economic importance of the crop as well as disease, present study was undertaken to conduct collection of samples , isolation, identification, pathogenicity, study of different characters of pathogen, morphological variability, cultural variability and biochemical variability of selected isolates and in vitro evaluation and sensitivity test of different antibiotics, bioagents and fungicides against the disease.
The isolations were made from the symptomatic samples collected from different districts of Maharashtra viz. Beed (Xam-1), Parbhani (Xam-2), Akola (Xam-3), Budhana (Xam-4), Yavatmal (Xam-5), Nanded (Xam-6), Amaravati (Xam-7) and Aurangabad (Xam-8).
Bacterium Xanthomonas axonopodis pv. malvacearum was successfully isolated on Nutrient Agar basal culture medium. It produced pale yellow mucoid, shiny, glistering, bacterial colonies.
Pathogenicity of Xanthomonas axonopodis pv. malvacearum was proved by spray inoculation of the bacterial suspension on cotton variety Jaadoo, BG-II, (PLATE III) (A) in pots at ten to twelve leaf stage, after predisposition to humid condition for 24 h. The leaves were inoculated with the homogenized culture of Xanthomonas axonopodis pv. malvacearum. Prior to automization of the culture on leaf, the leaves were slightly injured with carborendum/celite powder. Seedlings were then retained under humid condition for 24 hrs. by covering the pots with plastic bag. Pots were adequately watered. Simultaneously uninoculated plants were maintained as control.
Cultural and morphological characters and variability such as colony colour and colony shape, colony size, cell shape, appearance, colony margin elevation and texture of X. axonopodis pv. malvacearum were studied on different culture media.
The studies on biochemical characteristics of Xanthomonas axonopodis pv. malvacearum showed their positive reactions for potassium hydroxide (KOH) solubility test, Gelatin liquification, H2S Production, catalase test, Tolerance to 5% NaCl whereas, negative response for Gram staining, indole production, Arginine test and Methyl red test.
The antibiotic sensitivity against eight isolates was studied by paper disk method. Copper hydroxide 500 ppm was significantly superior than all the treatments showing maximum inhibition zone in all 8 isolates of Xanthomonas axonopodis pv. malvacearum.
Description
The present study was carried out during academic year 2018-19 at Department Of Pllant pathology, Dr. P.D.K.V. Akola. This study deals with the cultural, morphological and biochemical variability and in vitro evaluation and sensitivity test of antibiotics and fungicides in the management Xanthomonas axonopodis pv. malvacearum.
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Citation
CHOLE RAMDAS NAMDEO. (2019). VARIABILITY AMONG DIFFERENT ISOLATES OF Xanthomonas axonopodis pv. malvacearum.Department of Plant Pathology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. M. Sc. 2019. Print. xiv, 76p. (Unpublished).