1. Introduction
Biological value of agricultural products depends on the quality of growing medium — soils. Biological elements presented in soils are transferred into plant and thereby into the food chain. Selenium is an essential micronutrient, required by animals and humans in small amounts for basic vital functions. It is an integral component of glutathione peroxidases, which are important antioxidant enzymes that catabolize hydroperoxides [1]. Its level in human organism is dependent on its content in the soil–plant system [2], [3] and [4].