Fig. 3.
(A) Leaf CO2 uptake rate (A sat), (B) quantum yield of photosystem II (ФPSII), (C) stomatal conductance to water vapour (g s), and (D) ratio of intercellular to atmospheric CO2 concentration (c i/c a) for warm conditions prior to chilling treatment, after transfer of plants to chilling (day 0), on the 11th day of chilling treatment and 1 d after transfer of plants back to warm conditions (12th day of the experiment—recovery). Plants were grown at 10 °C/5 °C (chilling) or 25 °C/20 °C (warm) day/night, with a 14h day/10h night cycle under 1000 μmol photons m–2 s–1. Measurements were taken during the daytime. In all panels, accessions are ordered according to A sat on day 12 of the experiment [from the highest to lowest; A, fourth bar (black fill) for each genotype]. For each treatment stage, asterisks indicate significant differences in comparison with M. ×giganteus (3x) ‘Illinois’ based on Dunnett’s test (*P≤0.05; **P≤0.01). Subsequent time point values for Mxg (3x) ‘Illinois’ were: (A) 18.29, 7.99, 7.19, and 15.63 (μmol m–2 s–1); (B) 0.21, 0.08, 0.07, and 0.22 (dimensionless); (C) 0.13, 0.12, 0.08, and 0.13 (mol m–2 s–1); (D) 0.40, 0.74, 0.60, and 0.44 (dimensionless). Data are the mean ±SE (n=4). F1, the first generation of Msa×Msi hybrids; Msa, M. sacchariflorus; Msi, M. sinensis; Mxg, M. ×giganteus; P1 (high), parent 1 of interspecific Msa×Msi hybrids (Msa with high chilling tolerance).