The contents of amino acids and sterols in maize plants growing under different nitrogen conditions

The effect of nitrogen nutrition on phytosterol and amino acid content in aboveground biomass of maize (Zea mays L.) was investigated in a pot experiment. For cultivation of maize plants nitrogen dose (2 or 4 g N/pot) was applied in the form of ammonium nitrate (An) for control treatments or urea ammonium nitrate solution (UAN). UAN solution was applied according to the CULTAN method (Controlled Uptake long Term Ammonium Nutrition). The content of amino acids as important nitrogen-containing compounds in plant biomass was affected by nitrogen nutrition. An increase of glutamine and asparagine levels in maize aboveground biomass was observed after UAN solution application. The results of free p-sitosterol analyses by HPLC showed its 94% increasing concentration after UAN application in contrast to AN treatments. Our results confirmed that sterol interconversions are controlled by environmental conditions and they are involved in the regulation of membrane properties in response to changing growth conditions.