Figure 2. Stem elongation when a 12 hrs PAR light (110 µmol m^-2 s^-1) was extended for 12 hrs with monochromatic R or FR at different irradiances. In SD control, 12 hrs of PAR light was extended with 12 hrs darkness. Each point is an average of 16 plants that have been under experimental condition for one month. Standard deviations at the end of the experiments are shown.