Breeding Long Vase Life by Crossing and Selection for Five Generations in Dahlia (<i>Dahlia variabilis</i>) Cut Flowers, and Selection of Fourth-Generation Line 003-15 with Ultra-Long Vase Life

Genetic improvement of flower vase life is an important breeding target for ornamental plants. As the cut dahlia (Dahlia variabilis) flowers very short, we initiated a conventional crossbreeding research program in 2014 to improve it. We evaluated seedlings during summer (from July early September) develop dahlias that grow and bloom under high temperatures have excellent Japanese conditions. Crossing selection over five generations greatly improved life. The mean increased from 4.4 days 1st generation, derived 22 parental cultivars, 8.0 5th net increase 3.6 days. Mean significantly by 1.6 4th indicating continued improvement. 12 lines selected 3rd ranged between 6.0 15.9 distilled water 7.8 14.6 GLA solution (10 g·L−1 glucose, 0.5 mL·L−1 CMIT/MIT [isothiazolinone derivatives], 50 mg·L−1 aluminum sulfate). Vase was further extended 4.0 using 6-benzylaminopurine (BA) sprays compared alone. In particular, 4th-generation line 003-15 13.8 (2.5× ‘Kamakura’, leading white cultivar Japan) water, 12.0 (1.8× 2.2×) GLA, 13.9 15.3 (1.7× 1.9×) GLA+BA winter spring. Cut harvested July–August at 28°C with treatment also had long pedigree suggests genes related ‘Micchan’ (with life) may accumulated or duplicated 003-15. Finally, four lines, including 003-15, ethylene sensitivity, as 10 μL·L−1 caused petal abscission 2.0 2.8