Selenium Biofortification via Foliar Fertilization: Evaluating New Sources and Their Impact on Yield and Nutritional Quality of Grain Sorghum Grown in Tropical Soils

Background and Aims : Sorghum is vital for more than 500 million people worldwide and serves as an essential component of animal feed, particularly in Se-deficient regions. Foliar Se application represents an efficient and environmentally safer strategy compared to traditional soil fertilization with Se salts. This study aimed to evaluate the impact of novel Se sources on yield and nutritional quality across eight sorghum genotypes cultivated in tropical soils. Methods: The experimental design comprised foliar Se applications at 10 g ha⁻¹ using sodium selenate, potassium hydroxy-selenide, and acetylselenide, in addition to a control treatment (without Se), conducted in two contrasting field environments (Lavras and Lambari, Brazil). Results: The results revealed that Se fertilization significantly enhanced Se accumulation in both grains and shoots, with sodium selenate and acetylselenide showing the highest efficiency. The response to Se was genotype and field environments-dependent, with Nugrain430, Enforcer, and BM737 exhibiting superior performance in Se accumulation and grain yield. Selenium treatments also influenced macronutrient and micronutrient contents. Principal component analysis highlighted the strong interaction among Se sources, genotypes, and field environments, which affected both productivity and mineral composition. Conclusion: Overall, foliar Se fertilization proved to be a promising biofortification strategy, improving the nutritional quality of sorghum grains without compromising yield. The use of sodium selenate and acetylselenide, in particular, enhanced mineral uptake and protein content, demonstrating their potential for sustainable agriculture and nutritional security in Se-deficient regions.