The 'tidal salt marsh' ecotype of the halophyte Aster tripolium L. was grown in a nutrient solution with either a continuous or an intermittent NO3- supply with either Cl- or SO42- as the alternative anion. With increasing periods of NO3- supply per week the rate of the dry weight increment increased. When NO3- was supplied for longer than 48 h per week, the dry weight and the organic-N content in the shoots hardly increased, whereas the NO3- content in shoots and roots increased further. With alternated supply of a nutrient solution containing NO3- with one containing Cl-, the internal NO3- content in the shoot was lower than in shoots grown in solutions in which NO3- alternated with SO42-. It is concluded, that NO3- does not have a specific function in osmoregulation. |
