The aim of this project is to gain insight in the meaning of variation in phenotypic plasticity in response to salt stress. The species of this study, Plantago coronopus, grows mainly in the coastal zone where it is exposed to fluctuating concentrations of NaCl. The habitats are characterized by a highly variable abiotic environment, both in space and time. P. coronopus, although not a halophyte, can maintain growth at relatively high salinity.
High salinity does, however, cause a severe reduction of the reproductive output.
Reaction norms for life-history characteristics as well as physiological parameters need to be studied in relation to different, constant, or fluctuating saline conditions. Presence of costs on adaptability would mean that plants with a high fitness in one environment have a lower fitness in another environment. In all four environments there is a significant response in the selected charac-ter, the mean number of leaves, comparing high lines with control lines. At the same time leaf length and width decreased in the high lines. After four generations of artificial selection, the selection lines were tested both in a salt and non-salt environment.