The content of ß-sitosterol in maize plants growing under different nitrogen nutrition
The effect of nitrogen nutrition on phytosterol 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 per 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 lower nitrogen content in soil of UAN treatments in the first period of experiment and in following nitrogen application (30 days after maize sowing) affected yield and also total nitrogen content of aboveground biomass. The results of free ß-sitosterol analyses by HPLC showed the changes of its concentration after UAN application in contrast to AN treatments. The significant decrease of ß-sitosterol concentration (by 48 % in contrast to 1st period) was determined on UAN2 treatment in the 2nd period (8 days after nitrogen application). 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.