Cereal Chem. 73 (6):762-766 |
Changes in Wheat Grain Quality Due to Doubling the Level of Atmospheric CO(2).
C. Blumenthal (1,2,5), H. M. Rawson (3), E. McKenzie (4,5), P. W. Gras (1,5), E. W. R. Barlow (2), and C. W. Wrigley (1,5,6). (1) CSIRO Division of Plant Industry, North Ryde, N.S.W. 2113, Australia. (2) University of Western Sydney, Faculty of Agriculture and Horticulture, Richmond, NSW 2753, Australia. (3) CSIRO Division of Plant Industry, Canberra, A.C.T. 2600, Australia. (4) Agricultural Research Centre, R.M.B. 944 Calala Lane, Tamworth, N.S.W. 2340, Australia. (5) Quality Wheat CRC Ltd., Locked Bag No. 1345, PO, North Ryde, NSW 2113, Australia. (6) Corresponding author. E-mail: <email@example.com> Accepted August 23, 1996. Copyright 1996 by the American Association of Cereal Chemists, Inc.
Elevated levels of atmospheric CO(2) have been shown to increase grain yield and reduce grain nitrogen concentration. The object of this study was to determine whether elevated CO(2) levels would modify other aspects of grain quality relevant to processing, particularly protein and starch quality. Wheat of two genotypes (Hartog and Late Hartog) was grown in the field in controlled-atmosphere tunnels at either the ambient level of CO(2) (350 µl/L) or an elevated level (700 µl/L). This elevated level of CO(2) produced significant increases in grain yield, but decreases in 1,000-kernel weight. Grain grown in the elevated CO(2) atmosphere produced poorer dough and decreased loaf volume, farinograph development time, and dough extensibility. These changes were largely attributable to the lower protein content of the grain grown at elevated CO(2). There did not appear to be major changes in protein composition or in the functional properties of the protein. Grain produced at elevated CO(2) yielded starch with a significantly higher proportion of large (A-type) starch granules but no overall change in amylose-to-amylopectin ratio. These studies indicate that elevated levels of CO(2) may result in decreased quality of bread wheats largely due to lowered protein content.