Selection of Carnation Line 806-46b with Both Ultra-long Vase Life and Ethylene Resistance

Abstract

As the vase life of cut flowers is one of the most commercially important characteristics, genetic improvement of this trait is very desirable. Therefore, we started a breeding research program in 1992 to improve the vase life of flowers in carnation (Dianthus caryophyllus L.) using conventional cross-breeding techniques. We repeatedly crossed and selected promising progeny for three generations, from 2003 to 2010, in order to select lines that exhibit extremely long vase life and low ethylene sensitivity. In 2010, we finally selected a line, 806-46b, with both ultra-long vase life and ethylene resistance out of 50 progeny derived from a cross between 606-65S and 609-63S. The mean vase life of line 806-46b was 27.1 days (444% the value of a control cultivar, ‘White Sim’) at 23°C and 70% RH under a 12-h photoperiod, without chemical treatment, which was the longest vase life among the 6 cultivars and 7 lines tested. Line 806-46b also showed reduced ethylene sensitivity. The response time to 10 μL·L^–1 ethylene of this line was 21.8 h, whereas that of ‘White Sim’ was 5.8 h. Line 806-46b did not show brownish discoloration of petal edges during senescence, which was a typical senescence symptom of other selected lines with low ethylene production, when the flower lost its ornamental value. Instead, its petals exhibited gradual reduction of surface turgor by moisture loss as senescence proceeded. This unique senescence pattern is shared by our previously reported line 532-6 with an ultra-long vase life. Line 806-46b showed extremely low ethylene production at senescence, which was also true after ACC treatment. Exogenous ethylene treatment to flowers of this line induced ethylene production without petal wilting, indicating that autocatalytic ethylene production functions normally.