Figure 1. Spectral light treatments of bilberry plants.
(a ) Supplemental blue (460nm) and red (660nm) light treatments
provided by Heliospectra LED lamps. (b) Developmental stages of
bilberry: S1, flower; S2, small unripe green fruit; S3, large unripe
green fruit; S4, ripening purple fruit; and S5, fully ripe blue fruit.
(c ) Light spectra and relative light intensities in the light
treatments expressed in arbitrary units (AU).