Changes in Soluble Carbohydrate Composition of Barley, Wheat, and Rye during Winter
Olien, C.R. | Clark, J.L.
Significant increases in the production of winter cereals could be realized with improved hardiness. The objective of this research was to determine if overwintering cereals modify water soluble carbohydrate composition in response to naturally occurring winter freeze stress. Fields of wheat (Triticum aestivum L.), barley (Hordeum vutgare L.), and rye (Secale cereals L.) were monitored throughout the winter between 1986 to 1990 for snow-pattern development, temperature, and snowfall. Plant crowns were analyzed for freeze injury (form and intensity) and water soluble carbohydrate composition (fructan, sucrose, glucose, and fructose). Growth chamber plants were frozen and analyzed to confirm the interpretation of field plant data. In 1986, there was less fructan and more soluble sugars in the exposed than in the snow-covered wheat plants (but no complete depletion of fructan), and no crown injury from equilibrium freezing. In 1987–1988, little injury or fructan hydrolysis occurred in barley, wheat, or rye; the plants were snow covered during cold periods. In 1989–1990, fructan hydrolysis to sugar in exposed barley, wheat, and rye plants paralleled that in the exposed wheat plants of 1986–1987. The fructan content of exposed barley plants was nearly depleted during the coldest weather. Exposed plants had typical equilibrium freeze injury. Growth chamber plants responded similarly to the exposed field plants. Plants exposed to freeze stress converted fructan to sugars which probably alleviated adhesive freeze stress. The energy of hydrolysis may be useful for placing sugar into sites within the tissue where its cryoprotective activity is most effective. Cooperative investigations of USDA-ARS and Mich. Agric. Exp. Stn., East Lansing, MI.
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