
%0 Journal Article
%A Marcellos, H 
%A Burke, MJ 
%T Frost Injury in Wheat: Ice Formation and Injury in Leaves
%J Functional Plant Biology
%D 1979/08/01
%V 6
%N 4
%P 513-521
%K 
%R https://doi.org/10.1071/PP9790513
%U https://www.publish.csiro.au/paper/PP9790513 
%X Freezing of water in leaves of a number of wheat cultivars was studied using pulsed nuclear magnetic resonance (n.m.r.) spectroscopy; these data were coordinated with measurements of the temperature dependance of freezing injury, and used to analyse the freezing process and its effects. The freezing temperature which resulted in 50% loss of cell electrolytes on thawing. T50, varied from -7 to -12.1&#176;C in the material studied. Hardening treatments decreased T50 by 1.8&#176; in the least hardy cultivar, Kite, and 3.3&#176; in the most hardy cultivar, Cheyenne. Despite the contrast in hardiness level, freezing curves determined by n.m.r. were similar, the fraction of water remaining unfrozen, LT/L0, at temperature T having the relationship LT/L0 = &#916;Tm/T + b, where LT, L0 are the amounts of liquid water per unit dry weight at T and 0°C, respectively, &#916;Tm is the melting point depression and b the liquid water that does not freeze.    The freezing curves were similar because &#916;Tm varied little among hardy and less hardy samples. At their T50, the least hardy sample of Kite had lost 77.2% of its freezable water to extracellular ice at - 7&#176;C, whereas the corresponding value for the hardy Cheyenne was 86.8% at its T50 of - 12.1&#176;C. Greater hardiness in samples was closely associated with an ability to withstand greater amounts of freeze-induced dehydration, and not with alterations in &#176;Tm. 
