Breeding of promising tomato genotypes and hybrids against bacterial wilt.
Tomato cultivation was set back in Chongqing (China) due to severe incidence of bacterial wilt caused by Ralstonia solanacearum. Hence, studies were initiated to identify the pathogen, screen resistant resources, and breed hybrids with resistance to the disease. A total of 68 isolates of pathogen of tomato bacterial wilt was obtained during 2000-03. The morphological characteristics, cultural characteristics, biochemical properties and pathogenicity of the isolates indicated that they were R. solanacearum, race 1, and biovar III. Studied of methods of seedlings inoculation revealed that cutting and dipping method was the best one, compared with root-stabbing and leaf-clipping. Four tomato lines, which had high resistance to bacterial wilt, had been screened out from 184 genotypes. Among 12 hybrids that crossed from the 4 resistances, 4012 showed high yield, good qualities, and promising resistance.