Figure 1. (A) The cold stress index, calculated as the sum of low temperatures during the vegetative growth of sunflower, calculated using the SUNFLO crop model for two contrastinged environments: warm CO09 and cold LO10 from Mangin et al. (2017) and (B) the minimum and maximum daily temperatures for warm (CO09) and cold (LO10) environments in the experiment of Mangin et al. (2017). Error bars represent 1.5 times the interquartile range. (C) The control and chilling stress treatments (duration: three weeks) in the present study, the latter consisting of an 8 h night at 5°C and a 16 h day at 18°C.