Shading impacts on sorghum and soybean grain yields in agrivoltaics systems: Source-sink strength in response to shading

Agrivoltaics (AV) systems create consistent shading throughout the crop growth cycle, making it essential to understand how these patterns affect crop growth and development. If shading leads to a yield penalty, identifying the specific yield components involved is key to optimizing management practices for sustainable co-production of electricity and crops. This study investigated how sorghum and soybean respond to shading within AV systems, with a specific focus on identifying the key yield components and grain yield affected by shading. Canopy biomass, grain yield, and yield components (grain number and weight) of sorghum ( Sorghum bicolor ) and soybean ( Glycine max ) grown under full sun conditions and photovoltaic (PV) panel shadings were compared. Source-sink manipulation was achieved through defoliation and de-graining in both sorghum and soybean to determine the key grain yield components affected by shading in the AV system. The yield penalty from PV shading was pronounced in soybean, whereas it was minor in sorghum. Enhancing sink size (i.e., grain number) in both crops was the key factor for minimizing the yield penalty caused by shading. Management practices after anthesis would be different for sorghum and soybean in AV systems. Increasing assimilates in sorghum during grain filling may help offset yield penalties by boosting grain weight. For soybeans, the focus should be on avoiding resource limitations during post-anthesis, as increased assimilates had a limited impact on grain weight. Both crops integrated with PV electricity generation increased the Land Equivalent Ratio (LER: 1.54 for sorghum and 1.23 for soybean) in AV systems. AV systems improved land use efficiency despite reduced crop yields due to shading, demonstrating their potential for sustainable food and energy co-production.