Results presented in this paper are concerning the hybridization between the cultivated sunflower (Helianthus annuus, 2n=34) and the tetraploid species H. decapetalus (2n=68). The analysis of F1 hybrids between H. annuus and H. decapetalus and the study on the effect of backcrossing on cytological and phenotypical stabilization substantiate the conclusion that H. decapetalus, although not very closely relating to H. annuus, could be used in sunflowers hybridization programmes.
