THE EFFECT OF SOIL-WATER POTENTIAL ON SEED-GERMINATION OF SOME BRITISH PLANTS

‘Seeds’ of 15 species collected from a range of habitats contrasting in soil water status were germinated in soils of known matric potentials ranging from near field capacity to the permanent wilting potential (– 0.05, –0.5, –1.0 and –1.5 MPa). Germination was very sensitive to soil water potential and species responded in various ways. Some showed germination responses which correlated with the soil water status of their native habitat: none of the wetland species studied could germinate to any great extent at low soil water potentials; in contrast some species associated with drier habitats achieved high levels of germination in soils as dry as –1.0 MPa (and –1.5 MPa for one ruderal species). However, other species from drier habitats failed to germinate at low soil water potentials, and it is suggested that this may be a mechanism to avoid exposing the seedling to an unfavourable environment. Copyright © 1990, Wiley Blackwell. All rights reserved