Selenium is an antioxidant and an oligo-element for animals and humans. However, the concentration range between deficiency and toxicity is particularly narrow. This metalloid allotropic is introduced indirectly in the food chain via its accumulation in food plants. The literature on this subject is still restricted and incompleted, and traditionally realised on model plants and in presence of selenium in high concentrations. This thesis is about selenium transfer in a plant crop, Zea mays, and consequences of this accumulation on physiological plant through essential cations accumulation study (calcium, magnesium, iron, zinc, manganese, copper). For this, experiments in a controlled atmosphere chamber (hydroponic conditions) were performed to obtain samples then analyzed by appropriate analytical and sensitive techniques (HPLC, CRC-ICP-MS, ICP-OES or AAS-GF). Various factors influencing selenium transfer in plants have been studied: concentration and form of selenium source and stage of plant development. The results of this study showed that root absorption, concentration within the plants and their tissues, degree of selenium metabolization and volatilization, and therefore selenium intake in animals and humans, are strongly influenced by those three factors. Furthermore, this study showed that accumulation and distribution of cations within the plants depend on selenium -mainly at high concentrations. These effects may be associated with the system imbalance of reactive oxygen species detoxification in plant cells, consistent with the ambivalent nature of selenium mentioned in the literature: antioxidant or prooxidant depending on its concentration.
