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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