Effects of Salicylic Acid on Germination and Seedling Growth of Mirabilis jalapa L.: Implications for Ornamental Horticulture

Ornamental plants play a crucial role in urban landscapes due to their aesthetic and ecological value. Improving germination and early seedling development is essential for high-quality ornamental plant production. This study investigated the effects of different salicylic acid (SA) concentrations (0.00, 0.25, 0.50, 0.75, and 1.00 mM) on the germination and early seedling growth of Mirabilis jalapa L. under controlled greenhouse conditions. The results indicated that, among the tested concentrations, 0.25 mM SA increased the germination rate by 11.10% compared to the control group, and improved plant height, leaf number, and root length by 7.70%, 7.44%, and 11.49%, respectively. In contrast, higher concentrations (0.50, 0.75, and 1.00 mM) inhibited the growth parameters. Germination time was not significantly affected by SA treatments. These findings suggest that low-dose SA applications may positively influence early seedling vigor and growth performance, which can indirectly contribute to ornamental plant quality. This study provides baseline data for the potential use of SA in ornamental horticulture and highlights the need for further research on different species and environmental conditions.