Identification of tomato cultivars resistant to Ralstonia pseudosolanacearum

Abstract

The bacterium Ralstonia pseudosolanacearum is responsible for one of the main tomato diseases, bacterial wilt. The only effective control measure for this disease is the use of resistant cultivars. The aim of this study was to identify tomato cultivars resistant to Ralstonia pseudosolanacearum. The experiment was conducted in a greenhouse at the Federal Institute of Alagoas - Piranhas Campus. The experimental design used was entirely randomized in a factorial scheme (10 x 2), containing 10 tomato cultivars and two isolates of the species Ralstonia pseudosolanacearum, totaling 20 treatments in three replications, resulting in 60 experimental plots, each containing four plants. Using the diagrammatic scale of bacterial wilt scores, phytopathometry of the disease was carried out using the following variables: Incidence (INC), Bacterial Wilt Index (BWI), Disease Index (DI), Latency Period (LP50), Area Under the Disease Progress Curve (AUDPC) and Infection Rate (IR). These variables were obtained for the 5th − 10th and 15th − 20th day of evaluation. There was a significant interaction between Cultivars x Isolates for the following variables: BWI, AUDPC, IR (5th − 10th day of evaluation) and for BWI, DI and IR (15th − 20th day of evaluation). The variables LP50, INC, IR and AUDPC characterized the start of the bacterial wilt epidemic from the first evaluation interval, regardless of the cultivars and isolates. The cultivar Havaí 7996 was classified as resistant to the isolate CRMRs108, and the cultivar Bartô was classified as moderately resistant to both isolates.