Evaluation of eight tomato (Solanum lycopersicum L.) varieties for resistance to bacterial spot induced by Xanthomonas perforans

Abstract

The study was conducted to evaluate eight tomato varieties for their genetic resistance to bacterial spot, caused by Xanthomonas perforans(McCulloch &Pirone)with a view to identifying those which may be used for genetic improvement. In 2021, ten seeds each of the varieties were sown per pot and later thinned to two in the screen house. At 35 days after sowing (DAS), seedlings were inoculated with the suspension X. perforans. Plants treated with sterile distilled water served as control. Treatments consisting of the eight inoculated tomato varieties were arranged in a completely randomized design with four repetitions. Three days after inoculation (DAI), records were taken on symptoms appearance and subsequently at 48 hours interval until 31 DAI. Disease severity on leaves was assessed at each interval and between 70-80 DAS, disease incidence and severity on fruit was evaluated. Disease progress curve was drawn and area under disease progress curve was calculated. Records on the severity on leaves showed significant difference (P<0.05) among the varieties evaluated in this study with the highest (38.9%) and the least (25%) on Tima and RomaVF respectively. The highest incidence and severity on fruits (100%, 32.5%) were recorded on Tima variety, which were significantly higher than those recorded on other varieties (P<0.05). The least incidence and severity (15.0%, 12.5%) on fruit were recorded on Roma VF. Area under disease progress curve showed that Tima recorded the highest AUDPC (765), followed by UC82B (756) while the least was recorded on RomaVF variety (501). The study revealed that the tomato varieties evaluated varied in their responses to bacterial spot, with Roma VF been the least susceptible, none of the varieties was resistant to the disease.