Growth stage-specific modulation of resource acquisition, resource allocation, and growth-defense trade-offs in Brassica napus L. growing in an agrophotovoltaic system to enhance crop yield.

Agrophotovoltaic systems (APV) combine solar power generation with agricultural production, thereby alleviating increasingly fierce competition for land between food and energy production. How changes in the microenvironment by APV in different seasons affect plant adaptations at different growth stages is unclear. In this study, we used plant metabolomics to analyze the specific adaptation strategies and yield formation mechanisms of oilseed rape under the APV during the seedling and blooming stages. Under the APV, soil temperature increased. During seedling, oilseed rape adopted a resource-acquisition strategy to improve its growth and photosynthetic rates by reducing specific root length (SRL) and root tissue density (RTD), and increasing leaf chlorophyll content. The APV also promoted nutrient accumulation by increasing root soluble sugars and upregulating organic acid metabolites, while downregulating defense-related metabolites such as phenylpropanoids, thereby promoting growth during the blooming stage. During blooming, shading by the APV caused plants to switch to a resource-conservation strategy by increasing LMA, RTD, and chlorophyll content, reducing SRL, and improving resource-utilization efficiency. Plants shifted resources from growth inputs to starch storage in leaves and upregulated leaf lipid metabolism to increase yield. The changes in growth and defense strategies were regulated by hormones such as abscisic and indoleacetic acids. Our results show that it is necessary to explore the synergy between crops and photovoltaic modules by accounting for the microclimatic characteristics and crop growth cycles in a region to provide new ideas for improving land-use efficiency and optimizing the APV.