Fig. 2
Experimental setup of the light quality experiments. Interference filters of wavelengths ranging from 410 to 715 nm were placed in the slide stages of projectors. The photon-fluence rates were adjusted to 0.5, 1.0, 2.5 and 5.0 µmol m−2 s−1. Incubation of Petri dishes under white light with a photon-fluence rate of 5.0 µmol m−2 s−1 was used as a positive control for upward vertical migration (white Petri dish)