Foliar Application of Selenium Associated with a Multi-Nutrient Fertilizer in Soybean: Yield, Grain Quality, and Critical Se Threshold

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 Lanca and M5917). Two trials were conducted in a 4 x 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. Lanca 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 Lanca 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.

Automated summary

This study investigated the effects of selenium foliar application combined with a multi-nutrient fertilizer on soybean. The results showed that grain yield of soybean increased with the application of multi-nutrient fertilizer, while selenium rates linearly increased selenium contents up to 80 g Se ha(-1), regardless of the use of multi-nutrient fertilizer. The two genotypes (58I60 Lanca and M5917) had critical thresholds of 1.0 and 3.0 mg kg(-1) for grain selenium content, respectively. Selenium application promoted higher contents of K, P, and S in grains of genotype Lanca and higher contents of Mn and Fe in grains of genotype M5917. The findings highlight the importance of considering different fertilization strategies and genotypic variations when assessing the effects of selenium on soybean yield and grain quality.