INCIDENCE AND COLONISATION OF RALSTONIA SOLANACEARUM (SMITH) YABUUCHI ET AL. IN BRINJAL (SOLANUM MELONGENA L.) SEEDS IN RAJASTHAN, INDIA

Total seventy five seed samples of brinjal (Solanum melongena L.) collected from major areas of Jaipur districts of Rajasthan revealed 10-100% incidence of Ralstonia solanacearum (RS) on semi-selective TZC Agar medium. For the study all the seed samples were categorised into asymptomatic, shrivelled discoloured and heavily discoloured seeds. Dry seed examination of these samples revealed asymptomatic (07.75-97.5%), shrivelled discoloured (04.50-67.50%) and heavily discoloured (03.25-34.75%) seeds. Two naturally infected seed samples of brinjal carrying 100% incidence of RS were selected for histopathological studies. The heavily infected seeds were with or without epidermal appendages and with water-soaked symptoms. On bisecting such seeds the embryo and endosperm showed necrosis and browning. The pathogen was found confined to the outer seed coat layer particularly at funiculus in the asymptomatic seeds. In shrivelled discoloured seeds of brinjal it was found in seed coat, space in between seed coat and endosperm. It colonised in all the seed components including embryo and endosperm in heavily discoloured seeds. The pathogen caused necrosis, formation of lytic cavities, reduction in cell contents and aggregation of the bacterial cells. The pathogen was found extra- as well as intra embryonal.