Mapping Global Evidence on Genotypic Variability in Agronomic Performance and Nutritional Quality of Roselle Hibiscus sabdariffa Calyces

Roselle (Hibiscus sabdariffa L.) is grown across more than thirty countries spanning Sub-Saharan Africa, South, East, and Southeast Asia, North Africa, the Middle East, and the Americas, where seed lots and cultivars carry unevenly documented differences in calyx yield, color, vigor, and nutritional composition. This scoping review maps global evidence on genotypic and phenotypic variability in roselle and on the mineral, vitamin, pigment, seed oil, and antinutritional composition of its calyces, leaves, and seeds, following the PRISMA-ScR framework of Tricco et al. (2018). A structured search retrieved 224 records, of which 37 peer-reviewed studies met the inclusion criteria. Drawing on evidence from eighteen countries including Niger, Sudan, Egypt, Bangladesh, India, China, Thailand, Mexico, and the United States, roselle accessions differ several-fold in calyx yield, plant height, branch number, and flowering time, and calyx pigmentation tracks with anthocyanin concentrations that respond to water stress. Mineral, vitamin, seed oil, and leaf phenolic profiling reveal wide variation in calcium, iron, vitamin C, phenol, flavonoid, and fatty acid content among genotypes, while antinutritional compounds such as phytate, tannin, and oxalate stay within tolerable limits for most accessions, with one notable exception. Molecular markers resolve genetic groupings that only partly match morphological clustering. Evidence spans every major producing region but remains concentrated in West Africa, South Asia, China, and North America relative to East Africa, and no study combined agronomic and nutritional characterization of the same genotypes within one production system. Closing this gap could support breeding and germplasm conservation across roselle-growing regions where farmer-saved seed still dominates production.