Components of phenotypic variability for head diameter in sunflower - Helianthus annuus L.

Sunflower is the main crop species for the production of edible oil in many countries of the world, including ours. Plant height and head size, form and position on the stem as well as the number of leaves, their size, duration and distribution on the plant all play an important role in defining optimal plant architecture in sunflower hybrids (Škorić, 1975, 1989, 2002). In order to monitor the mode of inheritance and gene effects for head diameter in the F1 and F2 generations, half diallel crosses were made in six genetically divergent sunflower inbreds. The mean values of the trait in question differed significantly. The mode of inheritance of head diameter in the F1 generation was superdominance in all but four crosses, which had dominance instead. In the F2 generation, on the other hand, the prevailing mode was dominance, while superdominance was recorded in four cases. The dominant component accounted for the bulk of genetic variance, and the mode of inheritance of head diameter taking into account both the F1 and F2 generations was superdominance. These findings may prove valuable for developing high-yielding sunflower genotypes