Carbon Isotope Discrimination is Positively Correlated with Grain Yield and Dry Matter Production in Field‐Grown Wheat¹

Carbon isotope discrimination (Δ) is a measure of the ratio of the intercellular and atmospheric partial pressures of CO 2 . Variation in Δ within some C 3 species, including wheat ( Triticum aestivum L.), has recently been correlated with variation in water use efficiency of droughted plants grown in the glasshouse. The objectives of this study were to assess genotypic variation in a larger group of wheat genotypes grown at three locations, and...