Assessing Suitability of Sorghum to Alleviate Sub-Saharan Nutritional Deficiencies through the Nutritional Water Productivity Index in Semi-Arid Regions

Lack of cereal nutritional water productivity (NWP) information disadvantages linkages of nutrition to water–food nexus as staple food crops in Sub-Saharan Africa (SSA). This study determined the suitability of sorghum (Sorghum bicolor L. Moench) genotypes to alleviate protein, Zn and Fe deficiency under water-scarce dryland conditions through evaluation of NWP. Sorghum genotypes (Macia, Ujiba, PAN8816, IsiZulu) NWP was quantified from three planting seasons for various sorghum seed nutrients under dryland semi-arid conditions. Seasons by genotypes interaction highly and significantly affected NWP(Starch, Ca, Cu, Fe), and significantly affected NWP(Mg, K, Na, P, Zn). Genotypic variations highly and significantly affected sorghum NWP(Protein, Mn). Macia exhibited statistically superior NWP(protein) (13.2–14.6 kg·m(−3)) and NWP(Zn) (2.0–2.6 g·m(−3)) compared to other tested genotypes, while Macia NWP(Fe) (2.6–2.7 g·m(−3)) was considerably inferior to that of Ujiba and IsiZulu landraces under increased water scarcity. Excellent overall NWP(protein, Fe and Zn) under water scarcity make Macia a well-rounded genotype suitable to alleviating food and nutritional insecurity challenges in semi-arid SSA; however, landraces are viable alternatives with limited NWP(protein and Zn) penalty under water-limited conditions. These results underline genotype selection as a vital tool in improving “nutrition per drop” in semi-arid regions.