Development of tomato hybrids with multiple disease tolerance

Four lines and six testers were crossed to produce 24 F1 hybrids following Line x Tester technique to screen the material tolerant to blight and cucumber mosaic virus using integrated protocols of whole plant assay, mechanical inoculation and breeding. Check hybrid T-1359 was highly susceptible to late blight (LB) and early blight (EB) to the mark of 94 and 74 percent respectively and cucumber mosaic virus (CMV) with a 2.8 severity index. One hybrid Nagina x LB5 was scored tolerant to late blight with 35 percent infection, while four genotypes viz. LB3, LB2, LB4, LB7 and one hybrid Naqeeb x LB5 were tolerant to early blight with 28-30 percent infection and tolerant to cucumber mosaic virus with 2.1 severity index. Non-additive gene action was pre-dominant in genetic control of blights, viral diseases, yield and all yield related traits. Genotype Roma, LB5 and LB6 were found to be good general combiner for late blight while Roma, Nagina and LB2 for early blight. A high yielding hybrid Naqeeb x LB6 was the best one with 37.55 percent tolerance to late blight and 33.33 percent high yielder than T-1359. Most of the hybrids showed better tolerance to CMV as compared to T-1359. Identified good combiners can be used in heterosis and recombination breeding to develop high yielding and disease tolerant tomato genotypes. (author)