Influence of sowing dates and salicylic acid on the performance of Roselle (Hibiscus sabdariffa L.) under the agro-climatic conditions of Peshawar

Abstract Optimizing the growth and productivity of Roselle (Hibiscus sabdariffa L.), a valuable medicinal plant, is essential for maximizing its commercial and medicinal value. In this regard, an experiment was conducted to study the "Effects of sowing dates and salicylic acid concentrations on growth and production of Roselle" at Ornamental Nursery, The University of Agriculture, Peshawar, Pakistan. The experiment was performed in a randomized complete block design with a split-plot arrangement. Treatments were replicated three times. The experiment was comprised of two factors: factor (A) was different sowing dates i.e., 21st April, 1st May, 11th May, 21st May, and 31st May, and was assigned to the main plot, while factor (B) was salicylic acid concentrations at the rate of 0, 150, 200 and 250 mg L−1 which was subjected to subplot. Results showed that sowing dates and SA concentrations significantly (p ≤ 0.05) affected all measured variables, including days to flowering, plant height, number of leaves plant⁻1, number of branches plant⁻1, leaf area, stem diameter, number of calyces plant⁻1, fresh and dry calyx weight, and 1000-seed weight, whereas their interaction was not significant. Early sowing (21 April) and SA application at 250 mg L⁻1 individually produced the highest values for all growth and yield traits. Based on these findings, early sowing combined with foliar application of 250 mg L⁻1 SA is recommended to improve roselle growth and productivity under the agro-climatic conditions of the Peshawar valley.