Paclobutrazol and Cytokinin to Produce Iris (Iris x hollandica Tub.) in Pots

Nora Francescangeli1*

Because of the increasing and diversified demand for potted plants, there is interest in Argentina in commercial iris production (Iris x hollandica Tub.). Two experiments were performed at the Instituto Nacional de Tecnología Agropecuaria (INTA), San Pedro Agricultural Experimental Station (33º41’ S, 59º41’ W), Buenos Aires Province. The effects of increasing concentrations of paclobutrazol (PBZ) and combinations of PBZ and 6-benzylaminopurine (BA) were compared. Height, length of the cycle and rate of flowering were registered. Experiment 1: the bulbs were subjected to immersion in nine concentrations of PBZ: 0, 10, 20, 30, 40, 50, 60, 70 or 80 mg L-1 for 24 h. Experiment 2: the bulbs were immersed in three concentrations of PBZ: 0, 10 or 20 mg L-1 for 24 h and then in BA solutions: 0 or 5 mg L-1 for 24 h. In both cases, the cultivars evaluated were `Casablanca´ and `Professor Blaauw’. The bulbs were planted immediately after the treatments in 1 L capacity and 12 cm height pots, on 22 July 2008. PBZ allowed for reducing height in all treated plants. A concentration of 20 mg L-1 would be sufficient to achieve harmonious plants with the containers used: 33 cm tall, average reduction of 41 to 44% compared to the respective control (57 cm). For this concentration, the delay in the duration of the cycle was minimal: 3 to 4 days. There was no effect of BA on the variables. The rate of flowering was not affected by the treatments.

Keywords: Iris x hollandica, bulbous, growth regulator, height
1Instituto Nacional de Tecnología Agropecuaria INTA, Estación Experimental Agropecuaria San Pedro, Ruta 9 km 170, CP 2930 San Pedro, Argentina. *Corresponding author (nfrances@correo.inta.gov.ar).