Effect of NaCl on nitrate assimilation in barley

Abstract

Nitrate assimilation is related with nitrate reduction in leaves, stechiometric malate synthesis, malate transport to the roots as K-malate, decarboxilation and exchange of H003 by N03. Barley seedlings (5 days old) were cultivated during 5 days in nutrient solutions with 0,30, 60, 90, 120 and 150 me · l- 1 of NaCl. Cl-, N03, Na+, ~ and malate were analyzed in leaves at the end of experiment. Nitrate and nitrite reductase activity were tested during experiment. The activity of nitrate -and nitrite- reductase had not variations with the different NaCl treatments . The malate content in leaves decreased from 290 . 1 , without NaCl to 26. 6 ~eq.·g- 1 (d.w.)with 150 me·l- 1 of Na Cl in nutrient solution. Inleaves K+ is changed by Na+ and N03 was changed by Cl-. Decrease of malate can explain the effect of NaCl decreasing total, organic and inorganic nitrogen in the plant. It could be produced by Na:K or/and N03 : Cl .. relations.