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Fluorescein and its derivatives are yellowish-green emitting dyes with outstanding potential in advanced molecular probes for different applications. In this work, two fluorescent compounds containing fluorescein and an amino acid residue (compounds 1 and 2) were photophysically explored. Compounds 1 and 2 were previously synthesized via ester linkage between fluorescein ethyl ester and Boc-ser (TMS)-OH or Boc-cys(4-methyl benzyl)-OH. Studies on the time-resolved fluorescence lifetime and relative fluorescence quantum yield (φ) were performed for 1 and 2 diluted in acetonitrile, ethanol, dimethyl sulfoxide, and tetrahydrofuran solvents. The discussion considered the dielectric constants of the studied solvents (range between 7.5 and 47.2) and the photophysical parameters. The results of the lifetime and φ were compared with those obtained for compounds 1, 2 and fluorescein without an amino acid residue in alkaline aqueous solutions. Moreover, as a preliminary result compound 2 (S-cysteine) was tested in the presence of gold nanoparticles as an aggregation colorimetric probe.

Agronomic biofortification with selenium (Se) effectively reduces hidden hunger and increases the nutritional intake of Se in people and animals. Because sorghum is a staple diet for millions of people and is used in animal feed, it becomes a crop with biofortification potential. Consequently, this study aimed to compare organoselenium compounds with selenate, which is effective in numerous crops, and to assess grain yield, the effect in the antioxidant system, and macronutrient/micronutrient contents of different sorghum genotypes treated with Se, via foliar spray. The trials used a 4 × 8 factorial design, with four Se sources (control—without Se supply, sodium selenate, potassium hydroxy-selenide, acetylselenide) and eight genotypes (BM737, BRS310, Enforcer, K200, Nugrain320, Nugrain420, Nugrain430, and SHS410). The Se rate used was 0.125 mg plant−1. All genotypes reacted effectively to foliar fertilization with Se through sodium selenate. In this experiment, potassium hydroxy-selenide and acetylselenide showed low Se levels and lower Se uptake and absorption efficiency than selenate. Selenium fertilization increased grain yield and altered lipid peroxidation by malondialdehyde content, hydrogen peroxide content, catalase activity, ascorbate peroxidase, superoxide dismutase, and macronutrients and micronutrients content of the studied genotypes. In sum, biofortification with selenium led to an overall yield increase of sorghum plants and supplementation with selenium through sodium selenate was more efficient than organoselenium compounds, yet acetylselenide had a positive effect on the antioxidant system. Sorghum can be effectively biofortified through the foliar application of sodium selenate; however, studying the interaction between organic and inorganic Se compounds in plants is necessary.

Selenium uptake and its content in soybean grains are affected by Se application methods. This study evaluated the impact of Se foliar application combined with a multi-nutrient fertilizer (MNF) on soybean, establishing a Se threshold to better understand the relationship between Se content in grains and yield of two genotypes (58I60 Lança and M5917). Two trials were conducted in a 4 × 2 factorial design: four Se rates (0, 10, 40, 80 g Se ha−1) and two methods of foliar Se application (Se combined or not with MNF). Foliar fertilizers were applied twice, at phenological stages of beginning of pod development and grain filling. Grain yield increased with the application of MNF, yet Se rates increased Se contents linearly up to 80 g Se ha−1, regardless of the use of MNF. Lança and M5917 genotypes had grain Se critical thresholds of 1.0 and 3.0 mg kg−1, respectively. The application of Se favored higher contents of K, P, and S in grains of genotype Lança and higher contents of Mn and Fe in grains of genotype M5917. Our findings highlight the importance of addressing different Se fertilization strategies as well as genotypic variations when assessing the effects of Se on soybean yield and grain quality.