USING LINE x TESTER METHOD AND HETEROTIC GROUPING TO SELECT HIGH YIELDING GENOTYPES OF BREAD WHEAT (Triticum aestivum L.)

Studies on genetic gain, made by direct or indirect phenotypic selection, are needed regularly since they offer valuable information for breeding programs. The purpose of this study to investigate the gene effects on the yield-related traits of the F-1 and F-2 populations of bread wheat "linextester" crosses; to identify suitable parents and promising hybrids for development of high yielding varieties; to determine correlations between genetic distances of the parents and heterosis with heterotic groups (HG) based on specific combining ability (SCA). The combining abilities, heritability, heterosis (Ht)-heterobeltiosis (lib) and the potential of populations as a HG were analysed. According to the results, non-additive gene effects were predominated and narrow sense heritability was low for all examined features, significant combining ability effects were determined for some parents and hybrids. While DH18, D1120 and Harmankaya-99 were good combiners, "DH16xAltay-2000", "DH16xKate A-1" and "DH21xKate A-1" were promising hybrids. The yield, Ht and SCA were higher in inter-group hybrids than intra-group hybrids in HG. Although molecular markers are considered more reliable to create HG, only marker selection will not adequate to improve the trait in question because of complex genetic structure and environmental influence. Therefore, HG based on yield-specific SCA can be utilized as a reliable parameter in breeding studies.