Analysis of photosynthetic capacity of four apple canopy structures in China Tree structure and 3-D distribution of radiation in canopy of apple trees with different canopy structures in China Studies on Relationship among Character of Canopy Light Interception and Yield in Maize Populations(Zea mays L.) Spatial Distribution and Seasonal Changes of Needle-leaf Area Density within 17-year-old Chinese Fir Crown Digital modeling of light distribution within the crop canopy in jujube-wheat interplanting system