The spectral distribution of solar radiation was obtained during August 1994 and June and August 1995, in an area of the Atlantic Forest at "Parque Estadual Intervales. Base do Saibadela" (24º14'S and 48º04'W), Sete Barras, SP. The light spectra were obtained with the aid of a LI-1800 spectroradiometer in 22 spots under canopies, and three spots in an open area under conditions of overcast and sunny day. The PPFD and R/FR ratio (655-665/725-735nm) were used for radiation analysis . The quality of light was not influenced by the clouds but under the canopy there were significant differences (P<0.05) in the R/FR ratio (0,54 ± 0,08) in overcast and sunny day conditions (0,27 ± 0,07). This alteration in the quality of light due to the long periods of rainy days in the region can be of great significance for the photomorphogenic processes of plants that occur in this environment.
solar radiation; Atlantic Forest; phytochrome; R/FR