Six hundred and sixty F6 plants obtained from the crossing of cultivars CL5915-93 (moderately resistant) and IPA-6 (susceptible) were screened for resistance to bacterial wilt (Ralstonia solanacearum) under field conditions (28 ± 4ºC and RH 70 ± 5,5%) in March 1996 at UFRPE. Twenty-day-old seedlings were inoculated with biovar III of the pathogen by pouring 5 ml of a suspension (5x10(8) UFC/ml) at the base of each seedling, two hours prior to transplanting. Evaluations were performed at weekly intervals until 70 days after inoculation. At the end of the crop cycle, 151 symptomless plants were selected and from this material one progeny was backcrossed with the cultivar IPA-6. 40 progenies (F2) from this backcross were screened for resistance under greenhouse conditions (35 ± 5,5ºC and RH 77 ± 2,5%) in September 1997, using the inoculation method previously described. Evaluations of disease incidence and severity were made four, seven, ten, thirteen and 16 days after inoculation. The resistance reaction was also evaluated through incubation and latency periods. Twenty-eight days after inoculation the existence of latent infection in the resistant progenies was evaluated through vascular discoloration and pathogen isolation from processing material. Disease incidence was observed in 95% of the progenies. Eight progenies were ranked as moderately resistant and eight as resistant. The average incubation and latency periods were short (4.5 at 4.8 days) for control susceptible progenies and long (11.6 at 12.9 days) for resistant progenies. Latent infection was detected in 45% of resistant progenies.
Lycopersicon esculentum; Ralstonia solanacearum; Pseudomonas solanacearum; genetic resistance; inoculation; controlled conditions; incidence; severity; disease progress curve; breeding
