Carbon-isotope discrimination by leaves of Flaveria species exhibiting different amounts of C3-and C4-cycle co-function

Carbon-isotope ratios were examined as δ13C values in several C3, C4, and C3−C4Flaveria species, and compared to predicted δ13C, values generated from theoretical models. The measured δ13C values were within 4‰ of those predicted from the models. The models were used to identify factors that contribute to C3-like δ13C values in C3−C4 species that exhibit considerable C4-cycle activity. Two of the factors contributing to C3-like δ13C values are …