Nitrate and ammonium uptake by wheat seedlings as affected by salinity and light

Abstract Nitrate (NO3‐) and ammonium (NH4+) are the two main forms of nitrogen (N) taken up by plants. Several environmental factors affect the uptake of N. This work was undertaken to study the induction of NO3‐ and NH4+ transport systems in wheat (Triticum aestivum L.) roots as affected by salinity and light. Wheat seedlings were germinated in sterilized vermiculite and plants were grown in a growth chamber under controlled conditions for eight days with a nutrient solution without N, and with or without sodium chloride (NaCl). Uptake rates of NO3% NH4+, or NH4++ NO3‐ were calculated by measuring the disappearance of N from the solutions. The NO3‐ uptake developed with time, either through induction or activation. Salinity pretreatments increased net uptake rates of NO3‐ and NH4 +, suggesting that plants were in a higher N‐deficient status when grown in saline conditions. Light decreased initial NO3”; uptake but had little effect on initial NH4+ uptake.