Imbibition temperature affects winterfat (Eurotia lanata (Pursh) Moq.) seed hydration and cold-hardiness response

Winterfat (Eurotia lanata (Pursh) Meg.) diaspores harvested from 1 Canadian and 2 USA sites were imbibed at 0, 5, 10, and 20 degrees C. It was hypothe sized that imbibition temperature affects seed hydration which is related t o cold-hardiness of winterfat, Weight gain was measured at 8-hour intervals until full hydration, and embryo water content was determined. Water conte nt of fully hydrated seeds differed among collections and lower imbibition temperatures were always associated with greater seed water content. Differ ences in water content of seeds imbibed at different temperatures was relat ed to cold-hardiness. When water content of embryos was measured, differenc es among imbibition temperatures existed, but were reduced. Differences in seed water content among imbibition temperatures were mainly due to endospe rm other than the embryo because the embryo hydrated faster than other seed parts, Suggestions were made for modeling seed water relations based on th is study.