Effect of Spraying Salicylic Acid and Cycocel on Some Vegetative and Floral Traits of Petunia hybrida L.

Abstract

Background: Plant growth regulators are organic, non-food compounds that are used in small quantities to stimulate, inhibit, or modify physiological processes in plants. Methods: The experiment was conducted in the lath house of the Agricultural Research and Experimental Station, University of Kirkuk, Kirkuk Governorate-Iraq, during the period from 2 December 2024 to 1 June 2025, to investigate the effect of foliar spraying with Salicylic acid at concentrations of (0, 250 and 500) mg L-1 and Cycocel at concentrations of (0, 250 and 500) mg L-1 on some vegetative and floral growth traits of Petunia (Petunia hybrida L.). The experiment was arranged according to a randomized complete block design (R.C.B.D). Result: The results were analyzed using Duncan’s Multiple Range Test at a probability level of 0.05. The results indicated that spraying with Salicylic acid at a concentration of 500 mg L-1 significantly increased plant height and produced the highest number of leaves per plant and flower diameter. In contrast, the growth retardant Cycocel, when applied at a concentration of 500 mg L-1, reduced plant height. Furthermore, both concentrations (500 and 250 mg L-1) significantly affected the number of leaves, number of branches, number of flowers and flower diameter compared with the control treatment.