Effect of different shade levels and paclobutrazol on growth and flowering of parrot impatiens (Impatiens niamniamensis Gilg)

This study aimed at developing Impatiens niamniamensis Gilg (Parrot Impatiens) as a dwarf, attractive potted plant with increased flower production. Stem cuttings with three nodes were planted and maintained under a polythene propagator for two weeks. They were gradually exposed to sunlight and then transferred to different shade levels (0%, 50%, 70%, and 80%). Each group of plants was subdivided into two groups, and one was treated with 25 mL of 5 mg/L Paclobutrazol (PBZ) during the sixth week. Plants that were exposed to 0% shade were burnt and wilted within one week after planting. This treatment was not considered for further analysis. The interactive effect of different shade levels and application of PBZ was significant (P < 0.0001) on plant height. However, it was not significant for internodal length (P >0.05). There was no significant effect (P >0.05) of different shade levels and PBZ treatment on maximum quantum yield (Fv/Fm), absorption in active reaction center (ABS/RC), or trapped energy flux (ET0/RC). The number of flower buds was significantly higher in PBZ-treated plants that were kept under 70% shade. Shade levels and PBZ treatment significantly affected on color intensity of the flowers, while the length was not significantly affected (P>0.05). There was a significant effect on the number of days taken to flowering among treatments (P < 0.0001). Flowering was delayed in PBZ-treated plants. The 70% shade level with PBZ treatment can be recommended as the best treatment combination to develop shorter plants with better flowering of I. niamniamensis.