Varietal and individual differences in cross-compatibility in the 2x x 4x crosses of cyclamen (cyclamen persicum mill.)

Varietal and individual differences in cross-compatibility in the 2x x 4x crosses of cyclamen, particularly those of diploid pistillate parents, were investigated. A factor of tetraploid formation and efficient methods to obtain progenies in the crosses are discussed. Different cross-compatibilities, depending upon the pistillate parents, were observed in the 2x x 4x crosses, whereas pollen parents scarcely affected fruiting and seed production. There were individual and varietal differences, and all progenies in the crosses showed tetraploidy. All the diploid pistillate parents producing tetraploid progenies through crossing had giant pollen grains. These results suggest the possibility that fertilization between a reduced male gamete from a tetraploid plant and an unreduced female gamete from a diploid plant results in tetraploid progenies. The individual and varietal differences of cross- compatibility among parents also suggest that the selection of diploid pistillate parents decides the formation of seeds. Thus, the selection of diploid pistillate cultivars and individuals, which can produce the tetraploid progenies, should be effective in the inter-ploidy cross breeding of cyclamen.