Phytoremediation of trace-level formaldehyde within complex mixtures by Dieffenbachia seguine: a diurnal physiological study

Formaldehyde, a Group 1 carcinogen, is a ubiquitous indoor air pollutant frequently encountered in residential and occupational settings. While most phytoremediation research utilizes acute toxicological doses, indoor formaldehyde typically exists at trace levels within complex mixtures of volatile organic compounds (VOCs) and particulate matter. This study evaluated the phytoremediation potential of the C3 ornamental plant Dieffenbachia seguine (dumb cane) for trace-level formaldehyde (0.4–0.6 ppm) derived from cigarette smoke, simulating a realistic, multi-component pollution scenario. Plants were exposed to smoke-derived formaldehyde in a closed system over a 24-h diurnal cycle to assess performance under light versus dark conditions, using Dracaena trifasciata as a reference benchmark species. Notably, D. seguine exhibited > 50% removal of formaldehyde within 2 h and achieved near-total removal (98.8%) after 24 h under light conditions. While removal under dark conditions was slightly lower (92.7%), the performance remained statistically comparable to the reference species, D. trifasciata. Despite a significant reduction in stomatal aperture (from 64 to 36%) as an adaptive response to smoke exposure, D. seguine maintained biochemical homeostasis. Statistical analysis revealed that while unexposed plants plants exhibited a typical light-induced increase in indole-3-acetic acid (IAA) levels, no significant diurnal differences in IAA were observed under smoke exposure, indicating a stabilized hormonal profile. Furthermore, no significant degradation was observed in chlorophyll levels or catalase (CAT) activity, confirming a high innate tolerance to trace-level oxidative stress. These findings suggest that D. seguine is a resilient biological sink for atmospheric formaldehyde and a superior candidate for sustainable indoor air quality management.