Figure 1.

Relative change in plant biomass at elevated [CO₂] compared to plants grown at ambient [CO₂], indicated with the dashed line, with and without (control) aphids (mean ± S.E. shown). Data from three experiments using replication with multiple chambers (Johnson et al., 2014) and multiple experimental runs (Ryalls et al., 2015) compared with the “chamber swapping” approach (Ryalls, 2016). All experiments used the same cultivar (Sequel) and similar levels of [CO₂] (400 vs. 600–640 ppm) and temperature (25–26 vs. 30°C).