Nitrate accumulation and growth of <i>Aster tripolium</i> L. with a continuous and intermittent nitrogen supply^*

Abstract

Abstract The ‘tidal salt marsh’ ecotype of the halophyte Aster tripolium L. was grown in a nutrient solution with either a continuous or an intermittent NO 3 − supply with either Cl − or SO 4 2− as the alternative anion. With increasing periods of NO 3 − supply per week the rate of the dry weight increment increased. When NO 3 − was supplied for longer than 48 h per week, the dry weight and the organic‐N content in the shoots hardly increased, whereas the NO 3 − content in shoots and roots increased further. With alternated supply of a nutrient solution containing NO 3 − with one containing Cl − , the internal NO 3 − content in the shoot was lower than in shoots grown in solutions in which NO 3 − alternated with SO 4 2− . It is concluded, that NO 3 − does not have a specific function in osmoregulation.