Influence of absicisic acid on flowering in Phalaenopsis hybrida Abscisic acid (ABA) in the buds (or flowering shoots) , leaves and roots of Phalaenopsis hybrida (cv. TS 340) was identified and quantified by gas chromatography-mass spectrometry- selected ion monitoring using hexadeuterated ABA as an internal standard. Leaves contained much lower levels of both free and bound ABA than did roots. Dormant buds contained a relatively higher level of free ABA, whereas no detectable free or bound ABA was found in flowering shoots either at a length of 2 to 3 cm or 7 to 10 cm. Dormant stage P. hybrida ( grown at 28¢J ), levels of free ABA in the roots were higher than those in plants with flowering shoots, the levels of bound ABA in roots exhibited opposite tendency. Free and bound ABA in leaves was slightly increased in plants with flowering shoots as compared to those in the dormant stage. In addition, exogenous ABA application at 0.1 or 1 µg per plant inhibited initiation of flowering shoots, especially at 1µg per plant. These results suggest the decrease in the free ABA contents in the roots and buds, but not in the leaves, is correlated with bud activation and development of flowering shoots. Protein synthesis and flowering in Doritis pulcherrima in relation to daylength Mature doritis plants (Doritis pulcherrima Lindley cv. S84 -3345) were cultured in plastic pots with 9-h (short-day, SD) and 16-h (long-day, LD) photoperiods, respectively. The main 9-h light period was under field conditions (30 ¢J day/20 ¢J night on average). The supplemental 7-h light conditions for the LD was in chambers with 14 £gmol. m-2 s-1 photosynthetic photon flux. When transferred to SD for 30 or 40 days the plants initiated flower spikes (90 % of the total plants) between 2.0 to 3.0 cm and 7.0 to 10.0 cm in length, respectively. In contrast, only 10 % of the plants producing flowering shoots were observed under LD conditions. Unique 21 and 103 kDa proteins were evident in one-dimensional electrophoresis of proteins from mature leaves under SD conditions. Two-dimensional gel electrophoresis confirmed that clear polypeptide spots with a molecular mass of 21 kDa at isoelectric point of 5.2 and 103 kDa at isoelectric point of 5.6 accumulated in leaves when flowering shoot reached 7.0 to 10.0 cm (4 to 5 flowe4 primordia apparent). Possibly, the 21 and 103 kDa proteins play the important role during initiation of flowering shoot in doritis. Polypeptide sequencing of P21 suggested a possible relationship to the product of cell division-like protein in Arabidopsis thaliana. It is clear that doritis is a facultative SD plant, and photoperiodic induction of its flowering is closely associated with changes of protein synthesis in its leaves.