Net photosynthetic (An) light induction curves were measured 15–19 days into the heat application. Plants were illuminated at a PAR or 1500 µmol m−2 s−1 after previously being held in low light (∼30 µmol m−2 s−1) for 30 min. An induction was faster in T-Oa-19 plants than the null segregant (Figure 4A). Further analysis showed that the apparent rate constant of activation(Ka)was significantly faster for T-Oa-19,with a rate of 0.176 min−1 compared with 0.160 min−1 for the null segregant (p < 0.001) (Figure4B). The reciprocal of Ka shows that it took over half-a-minute longer for the null segregant to reach steadys tate photosynthesis than T-Oa-19 (6.3 min cf. 5.7 min). These modest but significant differences as a result of the transgene are consistent with improved kinetics of Rubisco activation under hot conditions. Significantly faster rates of non-steady-state photosynthesis translated to higher but not statistically significant (p = 0.25) rates of steady-state photosynthesis between the two genotypes(Figure4C).