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.