Optimizing grain sorghum selenium biofortification through foliar fertilization: integrating novel selenium sources, genotype, and contrasting tropical soils

Background and aims Sorghum ( Sorghum bicolor L. Moench) is vital for more than 500 million people worldwide and is an essential component of animal feed, particularly in selenium (Se) deficient regions. Foliar Se fertilization is an efficient and environmentally safer strategy than traditional through the soil fertilization. This study evaluated the impact of novel Se sources on grain yield and nutritional quality across eight sorghum genotypes cultivated in tropical soils. Methods The experimental design involved foliar Se fertilization at 10 g ha −1 using sodium selenate, potassium hydroxy-selenide, and acetylselenide, alongside a control treatment without Se. Experiments were conducted in two contrasting field environments: Lavras and Lambari, Brazil. Results Selenium fertilization significantly increased Se concentration in both grains and shoots, primarily due to sodium selenate. In contrast, potassium hydroxy-selenide and acetylselenide resulted in Se concentrations in grains and shoots similar to the control. The response to Se depended on genotype and environment: K200, BRS310, and Enforcer showed the highest Se accumulation under selenate fertilization, while Enforcer and Nugrain420 showed increases in grain yield. Selenium treatments also affected macronutrient and micronutrient contents. Principal component analysis revealed strong interactions among Se sources, genotypes, and field environments that influenced both productivity and mineral composition. Conclusion In summary, foliar Se fertilization is a promising biofortification strategy that enhances the nutritional quality of sorghum grains and increases grain yield in selected genotypes. Sodium selenate was primarily responsible for increases in grain and shoot Se concentration. Conversely, acetylselenide and potassium hydroxy-selenide contributed mainly through genotype-dependent effects on grain yield, mineral uptake, and crude protein content rather than Se-enrichment. These findings underscore the importance of source selection for successful biofortification strategies in Se-deficient regions.