Agrivoltaics shading enhanced the microclimate, photosynthesis, growth and yields of vigna radiata genotypes in tropical Nigeria

In recent years, more agricultural lands are been converted to photovoltaic (PV) power plants for better return on investment. However, prioritizing energy generation over food production poses a significant threat to the well-being of the rapidly growing global population. Agro-photovoltaics (APV) provide an opportunity to integrate crop production under PV panels. The objective of this study was to investigate the effect of APV system on microclimate, photosynthesis, and agronomic performance of mungbean in a tropical environment. Five mungbean genotypes, Tvr18, Tvr28, Tvr65, Tvr79 and Tvr83 were assessed under three APV micro environments, East-west facing PV (WPV), West-east facing PV (EPV), and no PV (NPV) in a split plot design with 5 replications. Results obtained showed significant reduction (p < 0.05) in photosynthetic active radiation (5-47%), leaf temperature (3-9%), and in the proportion of potentially harmful unregulated energy reaching the reaction centers (19-23%) under the PV (% reduction in WPV > EPV). Relative humidity, photochemical energy conversion, plant height, number of leaves, pods, and seeds were increased significantly (p < 0.05) underneath the EPV compared to NPV. Seed weight also increased non-significantly under EPV while flowering and podding behaviour, leaf area and stem diameter were comparable (p > 0.05) in NPV and EPV. We report for the first time that microclimate, growth, photochemistry and yield performances of mungbean were improved under APV system in a tropical environment. The improved performances of mungbean under EPV compared to WPV suggest that PV orientation is important and should not be overlooked in APV system designs.