3. Results and discussion
As shown in Fig. 1 and Table 1, 1500 ppm PBZ reduced plant height by 50% compared to the non-treated plants. Water limitation for 10–30 days reduced the plant height and plant fresh weight in the plants that were subjected to water-deficit stress. This period of stress did not reduce these parameters in the PBZ-treated plants under water-deficit stress (Table 1). These results indicate that one PBZ-application to the soil of 3–5 cm high plants was effective for height reduction, but was unable to affect biomass during water-deficit stress. PBZ controls height as a cell and internode elongation inhibitor. It retards plant growth by inhibition of gibberellin biosynthesis (Fletcher et al., 2000, Hua et al., 2014 and Wanderley et al., 2014). Burrows et al. (1992) reported that PBZ reduced the height of Chrysanthemum cv. Lillian Hoek, but increased leaf thickness by adding layers of palisade and spongy mesophyll cells.