Hi Jane, That's a cool idea, but the 18O content of the water should not influence germination. Plants take up water with 16O and 18O equally well, and this should also be true for seeds. Many other biological processes do discriminate against heavy isotopes (18O in this case), so a high content of 18O could very slightly slow down some biochemistry, but the effect should be negligible because the abundance of 18O is always very low in water. Even when precipitation has a lot of 18O, it is still just a very small fraction of all the oxygen in water (<1%) Bill Oxygen and seed germination Jane McGary (Fri, 06 Dec 2019 14:35:28 PST) Available oxygen is necessary for successful seed germination, which is one reason why most seeds in saturated, dense media don't germinate as well as those in a loose medium. I was just reading an essay that referred to the observation that precipitation from storms contains a higher proportion of 18O (sorry, the 18 should be superscript) than the more common 16O isotope. This reminded me of hearing that some growers assert that exposing seed pots to rain and, especially, snowmelt, would encourage germination. Does the isotope of oxygen matter here? Or is the oxygen in water not available to the seeds? When I lived in the foothills where snow was more frequent, I would cover my seed flats with snow and let it melt, just in case what I'd heard was true. Have you heard these theories, and do you know if there's any value in them? Should I again start covering my seed flats with snow, in the event that any falls here near Portland this winter? Jane McGary, Portland, Oregon, USA _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/…/ - _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/…