Determination of unfrozen water in winter cereals at subfreezing temperatures.
The freezing of water in acclimated and nonacclimated cereals was studied using pulsed nuclear magnetic resonance spectroscopy. The quantity of unfreezable water per unit dry matter was not strongly dependent on the degree of cold acclimation. In contrast, the fraction of water frozen which was tolerated by nonacclimated winter cereals and by an acclimated spring wheat (Triticum aestivum L.) was less than in acclimated hardy cereals. The freezing curves had the following form:L(T) = L(0)DeltaTm/T + KL(T) and L(0) are liquid water per unit dry matter at T and 0 C, respectively. DeltaTm is the melting point depression and K is the liquid water which does not freeze.
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Crop Development Centre, Crop Science Department, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 0W0.