2017 ASHS Annual Conference

Gladiolus xhybridus flower is major cut flower in the world; U.S. production of Gladiolus is ~$20 million (w). The control of flowering is determined by environmental factors, such as photoperiod, temperature as well as plant growth regulators. Gibberellins (GA) and abscisic acid (ABA) both interact in gladiolus dormancy. The exogenous application of GA enhances uniform corm sprouting and flowering. Our objective is to analyze the influence of gibberellin inhibitors (GA-Inhibitors) and ABA for control of flowering. Gladiolus corms were dipped in varying concentrations of GA-inhibitors and ABA solutions. Phenotypic traits measured included corm sprouting, leaf height, flower spike height, and daughter corm / cormel production (number, weight). ABA significantly delayed sprouting but had no significance effects on leaf/flower spike heights and daughter corm number and weight. Low concentrations of GA-inhibitors delayed corm sprouting and reduced height, while high concentration significantly delayed sprouting, reduced height, daughter corms number & weight and inhibited flowering. On the other hand, high concentration of GA-inhibitors delayed senescence. These findings confirm the vital role of gibberellins in control of Gladiolus flowering. Future experiments will be conducted to determine whether different gladiolus cultivars respond to GA-inhibitors and ABA in a similar manner to ‘Vista’.