Nowadays, attention is focused on the lack of selenium in the average diet, which is a highly valued element in the body’s antioxidant system. The major metabolites of selenium are selenoproteins, which have an irreplaceable function in the body. This study focused on optimizing conditions for the biofortification of maize (Zea mays L.) with selenium (Se). Three separate pot experiments were conducted to identify the key factors influencing the efficacy of foliar selenium application. The experiments were designed to investigate the effects of different forms of selenium (selenite, selenate, and selenium nanoparticles) on maize development, the influence of the phenological stage of maize at the time of foliar Se application, and the optimal application rate of Se (100, 150, 200, or 250 µg). The results indicated that sodium selenate without a wetting agent was the most effective form for enhancing total Se content in maize, with the greatest accumulation being in leaves (3.01 mg/kg dry matter). Phenological stages (BBCH) 51 and 60 were identified as the most suitable phenological stages for Se application in terms of total Se content about 1 mg/kg in leaves and about 0.4 mg/kg in grain and the presence of organic Se compounds (mostly selenate ion and selenomethionine). We concluded from the study that a foliar application of 200 µg of sodium selenate per pot during these stages resulted in maximum Se uptake without adversely affecting plant yield. Further research is recommended to validate these findings under field conditions, paving the way for improved agricultural practices in selenium biofortification.

Selenium (Se) supplementation is?a?common practice in?dairy nutrition. However, the use of?biofortified feedstuffs remains a?not fully realized strategy to?enhance the Se content of?animal derived products. This study explored an?on-farm biofo...