CeBiTec Colloquium: 2009/03/19 Dr. Petra Hoegy, Institute for Landscape and Plant Ecology, Universität Hohenheim

2009/03/19, 10:15

CeBiTec Laboratory Building, Room G2-104

Free-air CO₂ Enrichment (FACE) of wheat: Grain yield and quality in response to atmospheric CO₂ enrichment

Abstract:

Atmospheric CO₂ enrichment is known to alter the carbon- and nitrogen-metabolism of important C3 crops such as wheat during vegetative development. Therefore, the availability of metabolites for the developing grain may be altered. To identify the specific response patterns of wheat during grain filling and element redistribution, a spring wheat cultivar (Triticum aestivum L. cv. TRISO) was grown for three consecutive seasons in a free air CO₂ enrichment (FACE) field experiment. CO₂ enrichment had beneficial impacts on aboveground biomass and yield, contrasted by predominantly negative effects on wholegrain quality aspects, which have to date received less attention. Although the thousand grain weight remained unchanged, the size distribution was significantly shifted to smaller grains, which may directly relate to a lower market value. Elevated CO₂ resulted in significant decreases of the total grain protein concentration and changes in the protein composition. Concentrations of minerals such as potassium, molybdenum and lead were increased, while manganese, iron, cadmium and silicon were decreased, suggesting that adjustments of agricultural practices may be required to achieve current grain quality standards. CO₂ enrichment resulted in an overall decrease of the concentrations of proteinogenic amino acids per unit flour weight. In addition, the amino acid composition on a protein basis was changed. The concentration of fructose and fructan as well as the amounts per area of total and single non-structural carbohydrates except for starch were significantly increased in the grains. The same holds for the amounts of lipids. With regard to mixing and rheological properties of the flour, a significant increase in gluten resistance under elevated CO₂ was observed. In agreement, alterations in the grain metabolom were identified as several amino acids, sugars, sugar alcohols, organic acids and other metabolites were up- or down-regulated in the high-CO₂ treatment. Elevated CO₂ is obviously affecting grain characteristics important for human and animal nutrition and industrial processing such as bread-making. Experimental evidence for these changes is still poor but deserves further attention.