Calyx Yield and Nitrogen Use Efficiency of Roselle (Hibiscus sabdariffa L.) as Affected by Variety and Levels of Nitrogen Fertilizer

Roselle ( Hibiscus sabdariffa L.) is an important beverage and leafy vegetable plant. Its growth and yield attributes are affected by constraints like poor soil fertility and lack of improved varieties. A field trial was conducted to assess the Calyx yield response and nitrogen use efficiency of roselle. The experiment consisted of 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) laid out in factorial combination arrangement in randomized complete block design with three replications. Data on calyx yield, growth variables and nitrogen use efficiency parameters were recorded and analyzed by using SAS version 9.4. Results showed that the variety 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 of these attributes 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 WG-Hibiscus-Jamaica variety. Higher NER (42.5 kg kg − 1 ) were recorded from WG-Hibiscus-Sudan while lower was recorded from WG-Hibiscus-Jamaica. Higher (12.5kg) and lower (0.7kg) AE were recorded from 92 and 115 kg ha − 1 N application 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. Nevertheless, further investigation of the response and efficiency of roselle varieties to nitrogen fertilization, including other nutrients at different locations should be undertaken to get ample data for a conclusive recommendation.