617-625Bacterial wilt caused by Ralstonia solanacearum is the most devastating disease of tomato resulting in huge yield loss in commercial growing pockets of Himachal Pradesh, India. Cold tolerant strains of this pathogen evolved in the recent past, particularly pathotype IIB, are responsible for causing bacterial wilt in cold and temperate regions. High temperature and humidity favours the incidence of disease. Resistant genotypes have been developed at various research centers, located within the country and abroad but these genotypes were not found suitable for growing in Himachal Pradesh as these are lacking in one or other characteristics. Therefore, 18 bacterial wilt resistant F4 progenies of tomato were evaluated along with two bacterial wilt resistant checks to identify the most promising progenies on the basis of nature and extent of genetic variability and heritability coupled with genetic gain. To ascertain the variability source structure, computation of principal component analysis (PCA) was also done. Estimates for phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability and genetic gain were found to be high for average fruit weight, total fruits per plant, marketable fruits per plant, marketable yield per plant, gross yield per plant and lycopene content that indicates the presence of sufficient variability ensuring ample scope for improvement through selection. High heritability allied with high genetic gain suggested the presence of additive gene action and thereby these traits could be considered as reliable indices for selection. For PCA studies, eigenvalues were calculated for 16 morphological traits and the results revealed that the initial eight traits exhibited more than 0.5 eigenvalues and above 95 per cent of genetic variability. Hence, these traits can be considered for effective selection of developing elite bacterial wilt resistant lines in tomato
