Studies on flowering and fruiting of Taiwania cryptomerioides

Thirty-five Taiwania cryptomerioides Hay. clones in a Tsuyunshan seed orchard established in 1981 in the central part of Taiwan were observed for production of cones in 1999, 18 yr after field planting. In previous studies, flowering was not stimulated by gibberellin application. The aim of the study was to identify gibberellin and cytokinin substance in T. cryptomerioides. Different physiological of material were used and exogenous GA3, GA4/7 , and paclobutrazol were applied to similar material to examine the flowering response. However, changes in endogenous gibberellins and cytokinins during flower development remain essentially unknown, especially for T. cryptomerioides. The content of endogenous gibberellin and cytokinin in T. cryptomerioides at vegetative, early floral initiation, and flower development stages were investigated. We also determined the influence of exogenous gibberellin and paclobutrazol treatment on the shoots at different stage in relation to floral initiation. Extract of T. cryptomerioides needles were purified by reversed phase HPLC and gibberellin/cytokinin-like compounds were analyzed by GC-MS. The major gibberellin components were indentified as GA1, GA3, GA4 and GA7 while smaller amounts of GA8, GA9, GA24, GA29, GA53. The major cytokinin components were indentified as zeatin, zeatin riboside, dihydrozeatin.