In vitro production of flowering shoots in 'German Red' carnation: effect of uniconazole and gibberellic acid.

Callus regenerated near the base of senescing petals of flower bud explants of 'German Red' carnation (Dianthus caryophyllus L.) produced adventitious flowering microshoots on MS-medium containing benzylaminopurine (8.9 μM) and naphthaleneacetic acid (2.7 μM). When these microshoots were subcultured with some callus, additional adventitious flowering microshoots were produced from the callus. The production of adventitious flowering shoots continued for many subcultures spanning a period of more than two years. Uniconazole (6.9 μM) increased the number of adventitious shoots formed by as much as two-fold but decreased shoot length by about 50%. In contrast, GA3 (2.9 μM) decreased adventitious shoot formation and increased shoot length. Regardless of the growth regulator treatment, virtually all of the adventitious shoots produced flower buds. Thus, the growth regulators influenced flowering only indirectly by altering the number of adventitious shoots produced in vitro. These results demonstrate that the flowering habit of the adventitious shoots of 'German Red' carnation is highly persistent and the flowering stimulus continues to be transmitted to the newly formed microshoots through the callus.