THE EFFECTS OF OSMOTIC PRESOWING TREATMENT ON LABORATORY GERMINATION IN A RANGE OF WILD FLOWER SPECIES

Sown seed of many wild flower species have slow or delayed germination which can allow unsown and undesirable species to colonise a prepared site. Ideally all seed sown should germinate immediately. Priming see d in an inert osmoticum can improve synchronisation and speed of germi nation The objective of this study was to assess the efficacy of primi ng on a selection of 60 wild flower species from a total of 21 differe nt families. The majority of the species selected were common constitu ents of commercial seed mixtures. Seeds were primed in the light at 15 -degrees-C for 14 days in a polyethylene glycol '6000' solution giving an osmotic potential of either -10 or -15 bars. Priming had a highly significant effect on speed of germination reducing the median germina tion time by 2.8 +/-0.27 days in the -10 bar treatment and 1.6 +/- 0.2 7 days in the -15 bar treatment. At the species level, 28 species had significantly reduced median germination times following priming. Prim ing significantly enhanced the final germination percentage in 15 spec ies and significantly reduced it in eight species, with the adverse ef fect being more pronounced at -15 bars than at -10 bars. Non-hierarchi cal cluster analysis showed no clear patterns in response to priming e ither in relation to the comparative ecology or the plant family of th e species tested, with the possible exception of the Leguminosae speci es. Only one out of six members of this family showed any enhancement in germination rate or percentage. The study demonstrates that a primi ng treatment could improve speed of germination, in a wide range of co mmonly sown semi-natural grassland species.