Freezing of Water in Red-Osier Dogwood Stems in Relation to Cold Hardiness

Publisher Website
Google Scholar
Abstract
Studies of stem water in red-osier dogwood (Cornus stolonifera Michx.) using NMR spectroscopy indicated that most freezing occurs at temperatures above -30.degree. C in cold-hardy and tender stems. Hardy and tender stems had about the same amount of unfrozen water at -40.degree. C (0.28 g of water/g dry wt). When hardy stems were slowly cooled below -20.degree. C, the temperature below which little additional freezing occurs, they survived direct immersion in liquid N2 (-196.degree. C). Fully hardy samples not slowly precooled to at least -15.degree. C did not survive direct immersion in liquid N2. The hypothesis that cooling rate is an unimportant factor in tissue survival at and below temperatures where there is little freezable water was supported.