PREVALENCE OF Ralstonia solanacearum AS LATENT INFECTION IN POTATO TUBERS AT SELECTED COLD STORAGES OF NARAYANGANJ DISTRICT

Abstract

An experiment was conducted in the Molecular Phytobacteriology Laboratory of Department of Plant Pathology at Sher-e-Bangla Agricultural University, Dhaka during the period of May, 2018- October, 2018 to observe the prevalence of Ralstonia solanacearum in stored potato tuber collected from Narayanganj District of Bangladesh viz- Hazi Rahmatullah cold storage, Sahin cold storage and Ma cold storage. Ralstonia solanacearum was isolated from collected potato tubers and it’s morphological, biochemical and cultural features were studied. On NA medium, circular, mucoid, convex, lucid coloured colonies of bacterium were formed. It produced highly fluidal, slightly raised and creamy white colonies with light pink or pinkish red centre and irregular margin after 48 hrs of incubation at 30 o C on TTC medium. The bacterium was gram negative, rod shaped and showed positive result in KOH solubility test, levan production test, catalase test, oxidase test and pectolytic test. Incidence of Ralstonia solanacearum is significantly influenced by temperature, relative humidity, ammonia supply and O 2 supply & CO removal. Incidence varied significantly from one cold storage to another cold storage with increase of temperature. Maxmium incidence was 2 found in the month of October (26.21%) at temperature 4.44 ammonia supply 9 hours and O 2 supply & CO 2 o C, relative humidity 90%, removal 1hour at Ma cold storage. Lowest incidence was found 12.42% in May at temperature 1.67 o C, relative humidity 86%, ammonia supply 13 hours and O 2 supply & CO removal 1hour at Sahin cold storage. By correlation regression analysis confirmed that Maximum incidence was occurred at highest temperature (4.44 o C).