Control of Vegetative Growth and Flowering in Hedychium Coronarium Koenig

Abstract

The study was undertaken with the following objectives: i) To evaluate daylength treatments on flowering response in Hedychium coronarium. ii) To produce compact flowering plants adaptable to containerized production using a growth retardant (paclobutrazol). Daylength treatments of 8, 10, 12, 13, 14, and a natural daylength as a control was imposed on the plants between September 28 and December 20, 1997. The 13 and 14 hours provided adequate photo-inductive stimulus to elicit flowering response from the plants. No flowering occurred below 13 hours daylength. A subsequent night break (NB) treatment conducted between January 12 and May 10 1999 also induced flowering in the treatment plants, confirming that Hedychium coronarium is a long day plant. The NB consisted of 3.5 hours of light interruption from 11.30 pm - 3.00 am from two 100-watt tungsten filament lamps placed at 1.5 m apart and at 1.65 m above the pots. Hedychium coronarium plants were subjected to paclobutrazol drench applications of 2, 4, 8 and 16 mg a.i./pot. All treatments exhibited pseudostem length suppresing activity on the plants. However the 4 mg a.i./pot treatment was the best, limiting pseudostem length to 71% of the non-treated-control plants, with no adverse effect on the plants. The retardant did not impact other growth or reproductive parameters measured. A study to compare the relative efficiencies of drench and pre-plant rhizome dip applications of paclobutrazol found the rhizome dip method ineffective at 16.6 and 33 ppm. The drench concentrations of 2 and 4 mg a.i./ pot were highly effective in suppressing pseudostem length to 62 and 50% of non-treated control. The information generated by this study would be of practical value in scheduling an all year round flower production, as well as developing Hedychium coronarium for pot culture.