Lunar magnetism impairs wheat seedling photosynthesis: A simulated environment study.

Plants evolved under Earth's stable geomagnetic field (GMF), a condition sharply contrasting with the near-absence of a global magnetic field on the Moon. However, the effects of this stark magnetic disparity on fundamental plant processes like photosynthesis remain underexplored, particularly in the context of future lunar agriculture. This study rigorously investigated the physiological and biochemical mechanisms underpinning the photosynthetic response of wheat seedlings - a staple crop selected for its centrality in closed-loop life support - to a simulated lunar weak magnetic field (WMF, <5 nT). We used a controlled environment and simulated lunar soil to compare wheat seedlings grown under precisely controlled WMF and GMF conditions. Our findings reveal that WMF significantly impeded seedling growth, as evidenced by diminished height, reduced hydration, and lower biomass accumulation. Photosynthetic gas exchange was severely compromised under WMF, manifesting as reduced net photosynthetic rate, stomatal conductance, and intercellular CO2 concentration. Light and CO2 response curve analyses further revealed a fundamental reduction in photosynthetic efficiency, characterized by lower apparent quantum efficiency and maximum photosynthetic capacity. Concomitantly, levels of key photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids) and ferritin were significantly depressed in WMF-exposed seedlings, suggesting a mechanistic link to impaired photosynthetic machinery and potentially compromised nutrient uptake. This inhibitory effect of lunar-level magnetic fields on photosynthetic carbon assimilation is likely mediated by disruptions in light energy conversion, electron transport chain efficiency, and RuBP regeneration capacity. Furthermore, the observed reduction in ferritin, a crucial iron storage protein, may exacerbate oxidative stress and limit iron availability for chlorophyll biosynthesis. These combined disruptions indicate a significant constraint on plant productivity in lunar environments, thereby limiting the viability of purely terrestrial-adapted crops for lunar agriculture. These findings underscore the need to consider magnetic field mitigation strategies or genetically adapt crops for optimal photosynthetic function in weak magnetic field environments to ensure sustainable plant-based life support beyond Earth. This research provides a vital foundation for future investigations into plant magneto-biology and the development of robust agricultural systems for space exploration.