Partial shade effects of dual land use systems: Harnessing plant acclimation to drive sustainable farming solutions

Dual land-use systems such as agroforestry (AFS) and agrivoltaics (APV) are increasingly proposed as climate-resilient agricultural strategies, yet concerns remain regarding reduced light availability and its impact on crop performance. We conducted a multi-site field study across AFS and APV systems in Germany to assess photosynthetic acclimation in five arable crops (barley, beans, potatoes, cabbage, maize) using light response curves derived from leaf gas-exchange measurements using a portable photosynthesis system (LI-6800, LI-COR Biosciences, Lincoln, NE, USA). Across sites, crops consistently exhibited reduced dark respiration (Rd; 12–46%) and light compensation point (LCP; 20–54%) under shaded conditions relative to full sun, indicating acclimation that lowers respiratory costs and the irradiance threshold for positive carbon balance. In contrast, light-saturated assimilation (Asat) and apparent quantum yield (AQY) showed variable responses depending on crop type and system. These results demonstrate that commonly cultivated, typically sun-adapted crops exhibit physiological plasticity under heterogeneous field shading, particularly through reductions in Rd and LCP, challenging the assumption that such crops are inherently limited in shaded agricultural systems. While these responses do not directly translate to yield outcomes, they suggest that crops can maintain carbon balance under moderate shading and provide field-based evidence of photosynthetic acclimation and plasticity in these dual land-use systems.