Tolerance of Roselle (Hibiscus sabdariffa L.) Genotypes to Drought Stress at Vegetative Stage

Background: Hibiscus sabdariffa L. is an important medicinal and fiber plant in Sudan. Among other stresses, drought extremely limits the growth, quality and net yield of the crop. The drought effects the crop plants by imposing certain morphological, physiological and biochemical changes at different periods of growth. Methods: Current study was carried out in greenhouse settings at Center of Excellence in Molecular Biology (CEMB) to investigate the effects of drought stress. Five (5) different genotypes of Hibiscus sabdariffa L., namely Baladimostadir (H1), Um shiak (H2), Abu shankal (H3), Rahad mix (H4) and Abu Najma (H5) were studied. Thirty (30) days old Roselle seedlings were drought stressed for 10 days and its implications on plant growth, gas exchange, water relation, chlorophyll content and proline accumulation were estimated. Substantial genotypic differences in their adaptive response to drought were observed. Results: Drought stress significantly affected the plant height; lowered the relative gas exchange efficiency and altered the physiological and biochemical responses. In comparison with others, H2 and H4 genotypes tolerated the osmotic stress well with lower osmotic potential and higher osmotic adjustment, better water content, higher stomatal conductance, photosynthetic efficiency and chlorophyll content. Accumulation of osmoprotectant and gas exchange indicators clearly distinguished the responses of different genotypes towards water stress. Conclusion: Our results can be used for evaluation, screening, and manipulations of Hibiscus sabdariffa L. genotypes for improvement of drought tolerance through conventional breeding or drought responsive gene isolation.