Impact of Different Soil Enrichments on the Physicochemical and Antioxidant Potential of Red and White Calyx from Roselle (Hibiscus sabdariffa L.)

The red and white Hibiscus sabdariffa, were grown on a control soil and on soils enriched with organic manure, cow dung, goat dung, chicken droppings and NPK chemical fertilizers. Calyxes were gathered and characterized for their physicochemical and antioxidant potential. Results showed that the soil enrichment significantly (p < 0.05) affects the physicochemical properties of the two types of calyx. The red calyx exhibited the best nutritional value compared to the white one. Red calyx was richer in ash (18-23 mg / g fresh matter), calcium (2.21 to 4.34 mg / g), iron, manganese, fibres and phenolic compounds (5.1 to 7.4 mg / g) than the white calyx. However the later exhibited highest values of organic acids, copper and lipid content. Calyx harvested on soil enriched with organic manure had the best physicochemical characteristics compared to those obtained from soil enriched with NPK fertilizers. It is thus advisable to enrich soils with organic manure or chicken drops.