Data for Environmental Factors Have a Greater Influence on Photosynthetic Capacity in C4 Plants than Biochemical Subtypes or Growth Forms

Fan, Y., Noble, D.W.A., Medlyn, B.E., Monson, R.K., Sage, R.F., Smith, N.G., Ainsworth, E.A., Busch, F.A., Danila, F.R., Ermakova, M., Friesen, P., Furbank, R.T., Gan, S.H., Ghannoum, O., Griffith, D.M., Gu, L. Jacob, V., Knauer, J., Leakey, A.D.B., Li, S., Lombardozzi, D.L., Ludwig, M., Pathare, V.S., Peixoto, M.M., Prado, K., Sonawane, B.V., Still, C.J., von Caemmerer, S., Woodford, R., Way, D.A. Aug. 31, 2025. Data for: “Environmental Factors Have a Greater Influence on Photosynthetic Capacity in C4 Plants than Biochemical Subtypes or Growth Forms.” GitHub Repository.

Our understanding of how photosynthetic capacity varies among C₄ species and across growth and measurement conditions remains limited.

We collated 1696 CO₂ response curves of net CO₂ assimilation rate (A/C_i curves) from C₄ species grown and measured at various environmental conditions and used these data to estimate the apparent maximum carboxylation activity of phosphoenolpyruvate carboxylase (V_pmaxA) and CO₂-saturated net photosynthetic rate (A_max), two key parameters describing photosynthetic capacity. We examined how V_pmaxA and A_max vary with species-specific traits, growth and measurement conditions.

We found little systematic variation of V_pmaxA and A_max across the classical C₄ biochemical subtypes or growth forms, but showed that growth temperature and measurement conditions are major factors determining C₄ photosynthetic capacity. We found no evidence that common C₄ model species (e.g. maize, sorghum and Setaria viridis) differ in photosynthetic capacity from other C₄ species when grown in controlled environments. However, C₄ model species showed up to twice the photosynthetic capacity of other C₄ species when grown in the field.

Our multivariate model accounts for 47–51% of the variation reported in V_pmaxA and A_max, and we argue that environmental conditions have a greater influence on C₄ photosynthetic capacity than biochemical subtypes or growth forms.

GitHub: Supplementary datasets containing C₄ A/C_i data collated for this study and estimated apparent V_pmaxA and A_max used in the analysis.