<b>Seasonal variability of the relationship between the photosynthetically active radiation and the global radiation at the river Doce basin, Minas Gerais State</b> - DOI: 10.4025/actasciagron.v28i3.970

Abstract

The knowledge of the Photosynthetically Active Radiation (PAR) is important to different areas of vegetal physiology and agricultural sciences. Estimation models of the PAR based on the Global Radiation (GR) are extremely useful, since the GR is conventionally measured at the meteorological stations. Thus, the seasonal variability of the relationship PAR/GR was analyzed in five areas located at the river Doce basin, Minas Gerais State, Brazil, considering the dry and wet periods of the years 2001 to 2004. The relationships PAR/GR obtained for the dry and wet periods, and also to all data, presented agreement with those ones determined by several researchers in different areas of the world. Results showed that the relationships PAR/GR generally tend to be greater during the wet periods when compared with the dry ones. By this work, it could be concluded that there is interannual variability of this relationship, showing thus, the need to consider this variability to estimate the PAR based on GR appropriately.