A field experiment was conducted at Horticulture Farm of Agriculture and Forestry University, Rampur, Chitwan, Nepal from July 5 to October 20, in the year 2019 to evaluate the effect of concentrations of Gibberellic acid (GA3), Naphthaleneacetic acid (NAA) and Ethrel® on growth, flowering and yield attributes of a locally grown marigold (Tagetes sp.).The experiment was laid out in a Randomized Complete Block Design (RCBD) with 9 treatments viz. GA3 (100, 200 and 300 ppm), NAA (100 and 200 ppm), Ethrel® (100, 200 and 300 ppm) and a control (distilled water), and four replications. The application of plant growth regulators affected the growth, flowering and yield attributes by various degrees. The application of 300 ppm of GA3 resulted in highest values for plant height (92.77 cm), number of branches (34.43) plant girth (2.58 cm), duration of flowering (70.93 days), flower per plant (73.18), flower diameter (7.33 cm) and fresh weight of a flower (19.25g) and the yield (1409.03 gm) per plant while the same treatment resulted in the lowest value for days to the first flower initiation (49.06 days).Therefore, the application of 300 ppm of GA3 can be recommended to enhance the plant growth and flower yield of marigold.

Keywords: RCBD; Ethrel®; GA3; NAA