Fig. 4 Four days cultivation of U. lactuca in ASW medium enriched
with two nitrogen source. a Ammonium and nitrate concentration in
μM, b uptake rate in μM N g Dw−1 day−1 of ammonium and nitrate
when exposed to 50μM NH4Cl or 50μM NaNO3, c uptake rate in μM
N g Dw−1 day−1 of ammonium and nitrate when exposed to 50μM
NH4NO3; square is ammonium uptake rate of and circle is nitrate
uptake rate