Artificial Light at Night (ALAN) induces different photosynthetic activities and secondary metabolite accumulation in several plant species

It is well established that nighttime light exposure can negatively influence the physiological performance of plants. Nevertheless, the specific effects of artificial light at night (ALAN) on plants under natural conditions remain insufficiently understood. The Bogor Botanic Gardens (BBG) is widely recognized as an ex-situ conservation site for diverse plant species. Although BBG provides an ecosystem resembling natural habitats, its location within the center of a rapidly developing urban area exposes plant collections to direct and indirect anthropogenic pressures, including light pollution. In this study, we examined the impact of ALAN installations at BBG on fourteen plant species by quantifying several physiological parameters, including photosynthetic activity, stomatal conductance, chlorophyll content, secondary metabolite accumulation, and mineral nutrient concentrations. Our results demonstrated significant alterations in photosynthesis (A) and stomatal conductance (gsw) in several species exposed to ALAN. In particular, we focused on one secondary metabolite, neophytadiene, and observed that its content was consistently higher after treatments (T1 and T2) compared to pre-treatment levels (T0) in most of the tested species, indicating a measurable effect of ALAN. Furthermore, we detected a pronounced reduction in iron (Fe) concentration across five plant species, although this decrease did not appear to be directly associated with changes in photosynthetic performance. These findings provide valuable insights into the physiological responses of plants to ALAN and may inform strategies for plant selection in urban environments. Such strategies could help alleviate the adverse effects of light pollution on plant physiological functions and improve the sustainability of urban green spaces.