The following study aimed to investigate the effects of applying different concentrations of seaweed extract and balanced fertilizer on the medicinal active compounds in roselle (Hibiscus sabdariffa L.), as carried out during the growing season of 2023 at the Kerbala Governorate, Kerbala, Iraq. Employing a randomized complete block design with three blocks and two factors, the first factor was foliar spraying with balanced fertilizer at concentrations of 0, 2.5, and 5 ml L-1. Meanwhile, the second factor was foliar application with seaweed extract at concentrations of 0, 0.25, 0.5, and 0.75 ml L-1. Results showed significant differences among the spraying treatments with balanced fertilizer. The 5 ml L-1 spray treatment excelled in the concentration of quercetin, gossypetin, hibiscetin, protocatechuic acid, and sabdaretin in cup leaves, with averages of 0.282, 0.247, 0.190, 0.267, and 0.128 mg g-1, respectively. The seaweed extract concentrations also had a significant effect on the content of active compounds. Its enhanced concentration (0.75 ml L-1) showed increased values of active compounds, i.e., 0.349, 0.291, 0.235, 0.312, and 0.163 mg g-1, respectively. Notably also, the interaction between the factors has a remarkable effect on all the traits under study.
Roselle (H. sabdariffa L.), balanced fertilizer, seaweed extract, biologically active compounds, growth and yield traits
The balanced fertilizer foliar application (5 ml L-1) enhanced the ratios of medicinal active components as compared with other fertilizer treatments in roselle (H. sabdariffa L.). The active compounds also significantly gained improvement with the foliar spraying of seaweed extract at an increased concentration (0.75 ml L-1). The balanced fertilizer (5 ml L-1) and seaweed extract (0.75 ml L-1) produced the highest averages for all the medicinal components.