Fig. 4. Relationship between mean trial grain yield and the Pearson's correlation coefficient (r) of the relationship between grain yield and carbon isotope discrimination of mature kernels within the same trial (a). The correlation coefficients of the same relationships after subtracting the effect of DH are also shown (b). Each point represents a trial composed by 25 genotypes and four blocks per genotype. Trials were performed in NE Spain and SE Spain under two moisture regimes (irrigated and rainfed) and over 3 yr (1997–1999).