GENETIC STUDIES IN TOMATO (Solanum lycopersicum L.)

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Date
2019-05-22
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CSKHPKV, Palampur
Abstract
The present study was undertaken with a view to know the extent of heterosis, combining ability, gene action and genetics of bacterial wilt resistant in tomato (Solanum lycopersicum L.). Seven parental lines viz., BL 333-3, CLN 2123, 12-1, Palam Pride, BT-20- 3 (Yellow Egg Shape), Punjab Chhuhara and Roma were used to develop F1 hybrids through half diallel mating design (excluding reciprocals). All parental lines and hybrids were evaluated along with standard check Arka Rakshak in RBD with three replications under modified naturally ventilated polyhouse at the Experimental Farm, Department of Vegetable Science and Floriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur during spring-summer seasons of 2017 and 2018. The analysis of variance indicated significant differences among genotypes (G) for fruit yield and other component traits in all the environments. Significant differences for environment (E) and G × E interaction for most of the traits indicated the role of environment on the performance of genotypes/crosses. Combined analysis of variance also indicated that mean squares due to parents, hybrids and parents vs. hybrids were significant for most of the traits. Variances due to GCA, SCA and their interaction with environment were significant for most of the traits, indicating the importance of testing parents as well as hybrids across environments. The top cross combinations identified on the basis of per se performance, heterosis and combining ability for fruit yield and component traits were Palam Pride × BT-20-3 (Yellow Egg Shape), 12-1 × Palam Pride and 12-1 × BT-20-3 (Yellow Egg Shape) under protected environment. The estimates of GCA effects revealed that parents BT-20-3 (Yellow Egg Shape), Palam Pride and 12-1 were the most promising general combiners. For most of the traits, there was preponderance of non-additive gene action which reaffirms the importance of hybrids in tomato. However, there also exists sizable proportions of additive variance which can be utilized to develop pure lines. For the study of genetics of bacterial wilt resistance, two resistant (BL 333-3 and Palam Pride) and two susceptible (Punjab Chhuhara and Roma) parents were used to develop six generations (P1, P2, F1, F2, BC1 and BC2). It emerged that resistance to bacterial wilt disease was controlled by single dominant gene suggesting that development of hybrids involving at least one resistant parent is the best option for breeding tomato against bacterial wilt disease.
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