Plant height control of obligate long day herbaceous annuals using plant growth retardants and light

To control plant height of obligate long day plants, two trials were conducted, that is the use of plant growth retardants (A-Rest, Bonzi, and Cycocel), excluding control and exposure of plants to light for specific time (2, 4, 6 and 8 weeks). Results indicated that plant height was significantly reduced by all plant growth retardants. Similarly, plants transferred to a short day (SD) light chamber for 2 weeks produced more or less similar plant height when compared to plant growth retardants. The study suggested that for taller plants production the duration can be prolonged up to 8 weeks. The use of light to control plant height is non-toxic and eco-friendly. Key word: Obligate long day, herbaceous annuals, plant height control, plant growth regulators, light