Effect of sowing dates on genetic components in six-rowed barley
The genetics of yield and related traits was studied in barley ( Hordeum vulgare L.) by means of 10 × 10 half-diallel progenies (F 1 and F 2 ) at three sowing dates. An additive-dominance model fitted only for flag leaf area, spike length and 1000-grain weight at different sowing dates. Both additive (D) and dominance components (H 1 and H 2 ) were significant for all the traits studied, indicating the preponderance of dominance components in controlling the inheritance for these traits. The value of (H 1 /D) 1/2 indicated over-dominance for all the traits except for flag leaf area. Values of ‘F’ indicated an excess of dominant alleles in the parents for all traits except for flag leaf area. The environmental component ‘E’ was significant for all traits. The ratio of H 2 /4H 1 indicated the symmetrical distribution of genes for all the traits studied. The value of h 2 /H 2 was less than one for all traits except for spike length, suggesting that a dominant gene was involved in controlling the inheritance of spike length, whereas multiple genes controlled the inheritance of the remaining traits. The heritability estimates were relatively moderate for flag leaf area and 1000-grain weight, but low for all other traits. However, epistatic interactions had an important role in the expression of other traits. Breeding methods such as bi-parental mating in early segregating generations or diallel selective mating may be advantageous to combine important yield component characters for a tangible advance in six-rowed barley.