Effects of elevated CO2 on grain yield and quality of wheat: Results from a 3-year free-air CO2 enrichment experiment

Abstract

Spring wheat (Triticum aestivum L. cv. TRISO) was grown for three consecutive seasons in a free-air carbon dioxide (CO2) enrichment (FACE) field experiment in order to examine the effects on crop yield and grain quality. CO2 enrichment promoted aboveground biomass (+11.8%) and grain yield (+10.4%). However, adverse effects were predominantly observed on wholegrain quality characteristics. Although the thousand-grain weight remained unchanged, size distribution was significantly shifted towards smaller grains, which may directly relate to lower market value. Total grain protein concentration decreased significantly by 7.4% under elevated CO2, and protein and amino acid composition were altered. Corresponding to the decline in grain protein concentration, CO2 enrichment resulted in an overall decrease in amino acid concentrations, with greater reductions in non-essential than essential amino acids. Minerals such as potassium, molybdenum and lead increased, while manganese, iron, cadmium and silicon decreased, suggesting that adjustments of agricultural practices may be required to retain current grain quality standards. The concentration of fructose and fructan, as well as amounts per area of total and individual non-structural carbohydrates, except for starch, significantly increased in the grain. The same holds true for the amount of lipids. With regard to mixing and rheological properties of the flour, a significant increase in gluten resistance under elevated CO2 was observed. CO2 enrichment obviously affected grain quality characteristics that are important for consumer nutrition and health, and for industrial processing and marketing, which have to date received little attention. © 2009 German Botanical Society and The Royal Botanical Society of the Netherlands.