Effect of pH buffer solutions on seed germination of Hypericum pulchrum, Campanula rotundifolia and Scabiosa columbaria

Information about the applicability of buffer solutions to study the effects of pH on germination of grassland species is scarce. Germination responses of seeds of Hypericum pulchrum, Campanula rotundifolia and Scabiosa columbaria to citrate, phosphate, citrate/phosphate, borate, potassium hydrogen phthalate (KHP), 2-(N-morpholino)ethanesulfonic acid (MES), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and tricine buffers were tested at 20/10°C day/night temperature under 12 hours photoperiod. The germination of all three species was totally inhibited by citrate, phosphate, citrate/phosphate and borate buffers. Seed germination of C. rotundifolia and S. columbaria was also inhibited and that of H. pulchrum reduced by KHP and tricine. Moreover, C. rotundifolia germination was reduced by MES. HEPES buffer did not have a significant effect on germination of any of the three species. We conclude that, of the buffers tested, only HEPES is useful for the study of the effects of pH on seed germination of H. pulchrum, C. rotundifolia and S. columbaria.