Spatial and Temporal Dynamics of Photosynthetically Active Radiation in Crops: Effects of Canopy Structure on Yield

Understanding the spatial–temporal distribution of photosynthetically active radiation (PAR) within crop canopies is crucial for optimizing planting structures to enhance resource use efficiency and improve crop yields. While high planting densities are commonly employed to increase yields, this practice can lead to issues such as early leaf senescence and reduced biomass. This study investigates the impact of varying planting densities on PAR dynamics, canopy structure, and yield formation in maize over two years. Key findings include the following: (1) higher planting density significantly increased grain yield, biological yield, and LAI, although HI decreased; (2) canopy light distribution varied with planting density, with the middle layers intercepting the most light, particularly during the grain filling stage; (3) a density of 83,000 plants·ha−1 was the most efficient for maximizing yield and WUE, although high accumulated temperatures negatively impacted yields. These results suggest that adjusting planting density can enhance resource use efficiency in maize farming, particularly in regions with variable water availability and climate challenges. Future research should explore the long-term effects of planting density on soil health, water use efficiency, and crop resilience under varying environmental conditions. Additionally, studies integrating precision agriculture technologies to fine-tune planting density and water management in response to climate change are essential for ensuring sustainable maize production and food security in the future.