Desert Physio-Ecological Adaptation of Amorpha fruticosa to Dynamic Shading Under Photovoltaic Panels in a Sandy Region

The construction of photovoltaic (PV) power stations for sand control in northwestern China has exacerbated the conflict between solar resource utilization and ecosystem fragility, creating urgent ecological challenges that demand immediate solutions. This study investigated <i>Amorpha fruticosa</i> growing under fixed adjustable PV panels at the CGN DaLate Photovoltaic Leading Base in the eastern hinterland of the Kubuqi Desert. Through long-term field observations, three shading time gradients were established: heavy shading (HS), light shading (LS), and no shading (CK, control). The results clearly demonstrated that: (1) Plants in the LS treatment exhibited significantly greater plant height, basal diameter, and crown width compared to those in HS and CK, indicating optimal growth status and morphological plasticity. They maintained the highest net photosynthetic rate (Pn) and water use efficiency (WUE), while their intercellular CO₂ concentration (Ci) was significantly lower than in CK, effectively mitigating photosynthetic inhibition caused by high light intensity. Total chlorophyll (Chl) content increased significantly with increasing shading intensity, whereas the Chl a/b ratio decreased. (2) The LS treatment yielded the highest nitrogen (N), phosphorus (P), and crude protein (CP) contents, along with a more balanced N:P ratio, suggesting a superior state of nutritional metabolism. Growth indicators showed significant positive correlations with WUE and Chl content, and significant negative correlations with transpiration rate (Tr) and Ci, confirming a synergistic "physiological adaptation-growth optimization" mechanism. Our results demonstrate that light shading represents the optimal condition for the growth and biomass accumulation of <i>A. fruticosa</i>, highlighting its potential as a key species for vegetation restoration in PV power stations within arid ecosystems. These findings not only elucidate the plant's adaptation mechanisms but also provide a crucial physiological basis for selecting and managing understory vegetation, thereby supporting the optimization of integrative "PV-Ecology" systems for sustainable desert restoration.