Abstract

Roselle (Hibiscus sabdariffa L.) is an important beverage and leafy vegetable plant. Constraints such as poor soil fertility and a lack of improved varieties have an impact on its growth and yield characteristics. A field trial was conducted to evaluate Roselle’s calyx yield response and nitrogen use efficiency. In this study, two roselle varieties (WG-Hibiscus-Jamaica and WG-Hibiscus-Sudan) and six levels of nitrogen fertilizer (Kg ha^-1 (0, 23, 46, 69, 92, 105) were used in a factorial combination arrangement with three replications in a randomized complete block design. Data on calyx yield, growth variables, and nitrogen use efficiency parameters were recorded. WG-Hibiscus-Jamaica exhibited higher plant height (196.2cm) and branch number plant^-1 (34.9) from the application of 115kg ha^-1 N, while lower values were recorded on an unfertilized plot of both varieties. Variety WG-Hibiscus-Sudan exhibited the highest number of calyx plant^-1 (50.3), fresh calyx yield ha^-1 (5934 kg), and dry calyx yield ha^-1 (1866 kg) from the application of 92 kg ha^-1 N, while lower values were recorded from the unfertilized plot of the WG-Hibiscus-Jamaica variety. A higher nitrogen efficiency ratio (42.5 kg kg^-1) was recorded from WG-Hibiscus-Sudan while a lower value was recorded from WG-Hibiscus-Jamaica. Higher (12.5kg) and lower (0.7kg) agronomic efficiency were recorded from the application of 92 and 115 kg ha^-1 N respectively. WG-Hibiscus-Sudan was effective but not reactive, while WG-Hibiscus-Jamaica was not effective but reactive. In conclusion, for maximum commercial produce, calyx yield and profitability, applying 69 kg ha^-1 N on WG-Hibiscus-Sudan and 92 kg ha-1 on WG-Hibiscus-Jamaica was found best.