Late blight is a serious disease affecting tomato production especially in tropical and subtropical regions. Twenty-five crosses were generated from ten diverse parents to combine both the horizontal and vertical late blight resistance genes of late blight. Five inbred lines with polygenic resistance genes derived from interspecific cross Solanum lycopersicum x S. habrochaites f. glabratum were used as testers. The cultivars CN1 and CN2 CELBR as a source for vertical resistance genes Ph-2 and Ph-3. The genotypes were artificially inoculated with mixed isolates of Phytopthora infestans. Predominance of GCA effects suggested that additive effects were more important than non-additive effects. The testers lines were highly stable with respect to late blight resistance confirming the presence of polygenic resistance. The analysis of resistance in the inbred lines indicated that the resistance is controlled by recessive genes. The best combinations were NC2 CELBR x 64B and NC1 CELBR x 64B combined the bothgenetic makeup of resistant genes. The cross CELBR NC2 x 163A was the most suitable for intra-population breeding programs to late blight. The extensive background of resistance genes is promising to maintain its effect through the advanced backcross generations.
Key words: Solanum lycopersicum L., Phytophthora infestans, combining ability, interspecific cross.
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