Effects of seed provenance on germination of herbs for agricultural compensation sites

The germination characteristics of European provenances of seven weed and g rassland species which are used in agricultural compensation sites in Switz erland for example on set-asides, were investigated along a W-E gradient (E ngland, Germany, Switzerland, Hungary). In,growth chambers the germination increment with temperature was different among the four main species and pr ovenances tested. Consistently the English provenances were least responsiv e. The germination rate of Silene alba increased most strongly with tempera ture, Daucus carota and Leucanthemum vulgare were intermediate, whereas Cen taurea cyanus showed the lowest response to temperature. Germination of Dau cus was enhanced by alternating temperatures, and this effect was significa ntly higher for the most distant provenances compared with the Swiss seeds. Also in Leucanthermum and Silene the foreign provenances showed a stronger effect of alternating temperatures, whereas seeds of Centaurea were not af fected. In a common garden experiment Cichorium intybus, Daucus Leucanthemu m and Silence, but not Centaurea, revealed a trend towards lower germinatio n with increasing distance of the provenance. Germination phenology of the different provenances varied in the above species and in Hypericum perforat um, except the arable weeds Centaurea and Papaver rhoeas. A principle compo nent analysis confirmed that the overall variability among provenances was lowest in Centaurea, intermediate in Daucus and Leucanthemum, and highest i n Silene. The results suggest provenance-specific adaptations which were pa rtly correlated with the climate along the European gradient tested. Such a daptations can be used as an argument against the introduction of foreign s eeds for ecological compensation sites. (C) 1999 Elsevier Science B.V.All r ights reserved.