LINE BY TESTER COMBINING ABILITY ANALYSIS FOR EARLINESS AND YIELD TRAITS IN BREAD WHEAT (TRITICUM AESTIVUM L.) - K. Din; N. U. Khan; S. Gul; S. U. Khan; I. H. Khalil; S. A. Khan; S. Ali; N. Ali; Z. Bibi; K. Afridi; M. Ishaq; I. A. Khalil (Journal of Animal and Plant Sciences, 2020)
In the current breeding program, the development of new wheat genotypes with greater genetic potential has become an enduring target to assist in food security. Wheat breeders are also trying to develop such genotypes that can fetch maximum return with limiting resources. Line-by-tester combining ability analysis was carried out during 2015-2018 to determine the genetic divergence, general and specific combining ability (GCA and SCA) among lines, testers, and line by tester interactions, and legacy of agronomic traits in wheat. Six wheat lines i.e., IBWSN-177, IBWSN-52, IBWSN-131, SRN-09111, PR-107, and NR-21, and three testers i.e., Pirsabak-15, Shahkar-13, and Pakhtunkhwa-15 were crossed in a line by tester mating fashion. After advancing the generation, eighteen F2 populations and nine parental genotypes were grown in a randomized complete block design with three replications and assessed through line by tester combining ability. Analysis of variance revealed significant (p≤0.01) variations among genotypes (parental cultivars and F2 populations) for the studied traits. According to combining ability analysis, lines revealed significant (p≤0.01) variances for days to heading and harvest index, while merely significant (p≤0.05) for plant height and flag leaf area. However, line by tester interactions revealed significant (p≤0.01) differences for all the variables. Parental genotypes IBWSN-131, Shahkar-13, and F2 populations IBWSN-131 × Pakhtunkhwa-15, IBWSN-131 × Shahkar-13, and PR107 × Shahkar-13 were identified as promising general and specific combiners which performed better for earliness and yield traits. High by high, high by low and low by high general combiners were involved in F2 populations with promising SCA and best mean performance. In comparative involvement to the total variance, the lines and L × T F2 populations had a maximum share for the majority of the traits. Ratios of GCA to SCA variances and degree of dominance revealed that all the traits were managed by dominant gene action. Non-additive gene action suggested that selection of promising populations should be postponed to later segregating generations for further improvement.
Keywords: journal article; Additive and dominant gene effects; agronomic traits; the degree of dominance; F2 populations; genetic variability; GCA and SCA variances; Triticum aestivum L