PLANT GROWTH REGULATORS AND NON-INDUCTIVE PLANT ENVIRONMENT EFFECT ON GROWTH AND PLANT HEIGHT OF FACULTATIVE LONG DAY ORNAMENTAL ANNUALS

Seeds of facultative long day plants (Snapdragon cv. Coronette, Petunia cv. Dreams and Annual Verbena cv. Obsession) were sown into module trays containing leaf mould compost. After 70% emergence, two experiments were conducted to control plant height. In the first experiment, the plants of each cultivar were treated with standard dose of widely applied plant growth regulators i.e. A-Rest (Ancymidol) 30 ppm, Bonzi (Paclobutrazol) 30 ppm and Cycocel (Chlormequat) 1000 ppm and control. In second experiment, plants of same cultivars were kept under short day (SD) non-inductive environment for 2, 4, 6 and 8 weeks. After each time scale, these plants were then transferred to their long day (LD) inductive environment chamber until flowering. Results revealed that all the three plant growth regulators significantly (p0.05) reduced plant height of facultative long day plants as compared to control. Similarly, plants placed for a short duration (2 weeks) under SD non-inductive environment produced more or less similar results. However, if taller plants are required then this duration can be extended up to 8 weeks to obtain maximum plant height. The advantage of preferring non-inductive environment technique to plant growth regulators is that it is non-hazardous, environment friendly and less expensive.