Effect of Pinching, Salicylic Acid and Gibberellic Acid on Growth and Flowering Attributes in Dahlia

Background: Pinching and foliar application of plant growth regulators influence vegetative growth and flowering in ornamental crops. However, their individual and combined effects on different growth and flowering attributes of dahlia require further evaluation. Aim: To assess the effects of pinching, gibberellic acid (GA₃) and salicylic acid (SA) on growth and flowering attributes of dahlia. Methods: A field experiment was conducted during 2021–2022 at the Horticulture Research Farm, Banaras Hindu University, Varanasi, India. The experiment was laid out in a randomised block design comprising 14 treatments with three replications. Treatments included pinching and no pinching, foliar applications of GA₃ (100, 200 and 300 ppm), SA (100, 150 and 200 ppm), and a distilled-water control. Vegetative growth and flowering attributes were recorded and statistically analysed. Results: Pinching increased secondary branches (21.69 per plant), leaves (73.74 per plant) and flowers (63.94 per plant), whereas non-pinched plants exhibited greater height and earlier flowering. GA₃ at 100 ppm produced the maximum leaf number and fresh leaf biomass, while 200 ppm resulted in the highest flower number (71.05 per plant) and flower diameter (12.41 cm). GA₃ at 300 ppm produced the greatest bud diameter (21.35 mm) and peduncle length (22.87 cm). SA at 100 ppm increased flower longevity (5.29 days), whereas 150 ppm resulted in the longest flowering duration (44.42 days). Conclusion: Pinching, GA₃ and SA influenced dahlia growth and flowering differently. Treatment selection should therefore depend on the specific growth or flowering attribute targeted.