| ast studies have shown that sugar distribution within cells immediately before the onset of stress is critical to a realistic understanding of cryoprotection related to carbohydrates. Because spatial distribution of carbohydrates in cells are difficult to determine, compositional distributions were calculated from total carbohydrate amounts and related to freezing stress. Three barley (Hordeum vulgare) cultivars, differing in carbohydrate composition and in response to a controlled freezing test, were hardened under six light levels. At each level plants were freeze-tested and total crown sugars measured by water/ethanol extraction and High Pressure Liquid Chromatography. The log of a sugar to fructan ratio was linearly related to total carbohydrates. Experimental variability was eliminated by calculating simple sugar and fructan amounts at varying carbohydrate levels from the equations for the lines. The relationship between kill temperature and total carbohydrate was different for the three cultivars, suggesting a difference in sugar availability for cryoprotection. At approximately 100 mg carbohydrate/g dry wt. all three cultivars were killed at approximately... |
