Studies on the characteristics of photosynthetically active radiation under intercropping of wheat and maize

On the basis of observation on the incident and transmitted photosynthetically active radiation (PAR) of the winter wheat canopy under the monoculture and intercropping ways, the diurnal change of intercepti on photosynthetically active radiation (IPAR), the relationship between IPAR and leave area index(LAI), and the shading of the winter wheat were studied. The results show that there is a bimodal curve in the diurnal change of IPAR. When LAI is lower than 2, IPAR of intercropping is about 50% of that of monoculture; when LAI is larger than 2, IPAR is almost equal under two planting ways. In addition, there is a good relationship between IPAR and LAI. The results also show that there is a bimodal curve in the diurnal change of fraction of shading(FS), and a good relationship between FS and height(H).