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

Plant growth regulators are organic, non-food compounds that are used in small quantities to stimulate, inhibit, or modify physiological processes in plants.

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).

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.