Figure 5. Means (points) ± 1 standard deviation (SD) (error bars) of (A) plant height and (B) collar diameter for sunflower in control (red) and cold (blue) treatments. Plants were grown for three weeks in a growth chamber and then transferred outside to identical conditions, in which they were phenotyped. Arrows indicate the flowering date. (C) Means ± 1 SD of the growth rate of plant height and collar diameter, which was calculated using sigmoidal functions. Corresponding experimentations were 20HP01, 21HP01, 22HP02.
After three weeks of stress and transfer to identical conditions, the growth of cold-stressed plants (i.e., height and collar diameter) did not differ in response to early stress (Fig. 5A and B), and their mean growth rates did not differ significantly (Fig. 5C). However, stressed plants flowered ca. 2 d later and continued to grow in height, which resulted in plants ca. 20 cm taller.