Abstract
Interspecific hybridization between carnation (Dianthus caryophyllus) lines with a long vase life and D. superbus var. longicalycinus, a wild Dianthus species native to Japan, was carried out in order to combine early flowering, high productivity and long vase life. Although the interspecific hybridization of this combination was very difficult, seed was set in 4 of 22 crosses. Moreover, all obtained seeds were abnormal; the seeds were imperfectly solid and had a wrinkled brown surface. However, 15 F1 seedlings were obtained using normal cross-breeding techniques, without depending on in vitro culture. Selected F1 lines showed fertility in both seed and pollen parent. SSR analysis proved that all 9 selected F1 lines were interspecific hybrids. In backcrosses between selected F1 or BC1 lines and carnation lines with long vase life, the percentage of seed setting was markedly increased, and germination percentage of obtained seeds was also high. The mean vase life of the F1 generation was 7.0 days; in contrast, vase life of the BC2 generation, after two cycles crossing and selection using carnation lines with long vase life, had improved to 14.7 days, a net increase of 7.7 days. Carnation breeding using D. superbus var. longicalycinus was effective for selecting early flowering progenies. The F1 generation showed a very early flowering habit; average number of days to flowering in 15 F1 seedlings was 135 days. In BC1 and BC2 generations, segregation of seedlings with early flowering was also observed. Our findings suggest that flower vase life is not linked early flowering habit. Several selected BC2 lines with long vase life, early floweing and high productivity could be developed, even when using D. superbus var. longicalycinus, which has a very short vase life, as breeding material.
