Journal of Advances in Biology & Biotechnology

African marigold (Tagetes erecta L.) is an important commercial flower crop widely cultivated for ornamental, religious, and industrial purposes; however, its flowering and yield are greatly influenced by plant growth regulators and environmental conditions. This investigation, was carried out during the Rabi season of 2020–21 at Horticulture Research Farm-I, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh. The trial was arranged using a Randomized Block Design (RBD) with ten treatments and three replications, more or less. Basically, the treatments were foliar sprays of gibberellic acid (GA₃) at 50, 100, and 200 ppm, naphthalene acetic acid (NAA) at 100, 200, and 300 ppm, and Ethrel at 200, 300, 400 ppm. Alongside these, a control was maintained with just water spray. The outcomes showed that these bio-regulators had a strong and noticeable impact on flowering, yield, and the related traits of African marigold. When it comes to overall performance, GA₃ at 200 ppm turned out to be the best. It led to early bud initiation around 48.79 days, and also supported a longer flowering interval of 48.90 days. Other measured effects also favored this treatment, like an increased flower stalk length of 9.51 cm, higher number of flowers per plant (28.01), and bigger flower diameter (9.35 cm). For yield, GA₃ at 200 ppm produced the greatest flower yield, with 346.90 g per plant and 183.81 q per hectare. Ethrel at 400 ppm recorded the maximum flower weight (11.97 g), but it also caused a delay in flowering, you could say. Meanwhile, the control plants did not perform as well in most traits compared to the treated ones. So, the study can be concluded as, foliar spraying of GA₃ at 200 ppm is a highly effective option for improving flowering, flower yield, and overall quality of African marigold cv. Pusa Narangi Gainda, particularly under subtropical weather.