Occurrence of "flower browning" of cut Gypsophila paniculata L. and its prevention by harvesting at bud stage

Inflorescences of Gypsophila paniculata L. 'Bristol Fairy', harvested with 30% of their buds open, were held in deionized water and kept at 20, 23, 26 , or 29 degrees C. Petals of flowers held at 20 degrees C became translucen t and desiccated, although the floret shape remained unchanged. When the in florescences were kept at 23 degrees C or higher, the petals of open floret s turned brown, wilted and inrolled into calyxes; commercially the phenomen on is called "flower browning". Following a pulse of 0.2 mM silver thiosulf ate (STS); a continuous supply of 4% sucrose and 0.26 mM 8-hydroxyquinoline sulfate (8- HQS) to bud-cut inflorescences not only enhanced bud opening b ut also inhibited the occurrence of "flower browning" even under an inducti ve stress of 25 degrees C. Days between bud-cutting, when the terminal flor et had just open, to the marketable stage with 30% of open buds, were 5 and 3 at 20 and 25 degrees C, respectively. Light intensity of 15.0 W . m(-2) during the forcing period for bud opening after harvest was desirable for g etting marketable inflorescences with good quality and long vase life. The rate of respiration by cut inflorescences increased exponentially with incr easing temperature; the respiration rate at 20 degrees C was c. 210 mu mol CO2 hr(-1) . 100 gfw(-1) (Q(10) = 1.5). At 25 degrees C, a severe decrease in sugar content of florets occurred on cut inflorescences. On days 2 and 4 , glucose and fructose contents per floret at 25 degrees C were one-half to one-third of those at 20 degrees C; whereas sucrose content was almost one -fourth. Application of sucrose helped maintain a high soluble sugar level in florets which may contribute to prevent petals from wilting and browning even under inductive temperature conditions. Bud-cut inflorescences treate d with STS could be stored with their stem base in a solution containing su crose and 8-HQS at 1 degrees C for 4 weeks without lowering cut-flower qual ity and longevity.