Cytokinin treatment and flower quality in Phalaenopsis orchids: Comparing N-6-benzyladenine, kinetin and 2- isopentenyl adenine

Abstract

We previously documented an N-6-benzyladenine (BA) protocol to increase spike and flower number in Phalaenopsis orchids. To increase options for growers, we tested two additional cytokinins, kinetin (Kin) and 2-iso-pentenyl adenine (2-iP), comparing them with BA. Two key commercial cultivars were used (Phalaenopsis Sogo Yukidian ‘V3’ and Phalaenopsis Tai Lin Redangel ‘V31’). We counted spike number and length, flower number and diameter, time to anthesis and flower longevity. Whole plants were sprayed once with BA (50, 100 or 150 mg·L^-1), Kin (100, 200 or 300 mg·L^-1) or 2-iP (50, 100 or 150 mg·L^-1) either on day 1 of 26 /18°C treatment (Time 1) or when the first flower bud reached 0.2 cm in diameter (Time 2). Surprisingly, all three cytokinins increased flower diameter. With Phalaenopsis Sogo Yukidian ‘V3’ sprayed at Time 1, Kin (200 mg·L^-1) increased the number of spikes (1 to 1.5) and flowers (8.4 to 10.4 per plant). BA increased both spike and flower number. Also, at Time 2, BA (100 mg·L^-1) increased spike numbers. In the second cultivar, Phalaenopsis Tai Lin Redangel ‘V31,’ spike and flower number increased only with BA. Kin showed no effect in measured parameters, while 2-iP increased flower diameter and longevity. Although, BA was shown to be the most effective in increasing flower and spike number, this research suggests that non-BA cytokinins are useful for increasing flower quality in Phalaenopsis orchids.

Key words: 2-Iso-pentenyl adenine (2-iP), kinetin (Kin), spike number, flower count.