Assessing phytomonitoring potential employing air pollution tolerance index and oxidative stress markers for selective flora in metrocity-Lucknow, India

Growing ambient air pollution in Lucknow is a menace to the monuments, urban dwellers, and the ecosystem. In view of the above, air pollution tolerance potential of dominant plants against air pollutants was assessed supported by indices and statistics. The study was conducted at three sampling sites in Lucknow city: commercial, industrial, and rural in the years 2021-22. PM_2.5 concentrations were 163.4 ± 25.3, 155.1 ± 14.6 and 113.2 ± 30.8 µg/m³ at commercial, industrial, and rural locations, respectively, breaching national ambient air quality standards (60 µg/m³) by 172.3, 158.5 and 88.7%. Eleven trace elements were associated with PM_2.5 and PM₁₀ out of which Sr, Al, Fe, and Zn were predominant owing to road dust entrainment and vehicular emission. Biochemical parameters were assessed for four native floral species Azadirachta indica, Mangifera indica, Ficus religiosa and Cascabela thevetia. For these species, pH ranged between 5.3-8.4, total chlorophyll 0.4–1.2 mg/g, carotenoids 0.15–0.34 mg/g, relative water content 32.1–89.9% and ascorbic acid 0.12–1.32 mg/g. Guaiacol peroxidase (19.5 ± 2.5 U/gm protein) was highest for C. thevetia, malondialdehyde (3.6 ± 1.4 nmol/gm FW) for A. indica, superoxide dismutase (339.4 ± 11.7 U/mg protein) for C. thevetia and catalase (688.7 ± 68 U/mg protein) for A. indica. Air pollution tolerance index (APTI) was higher for F. religiosa (17.53) followed by A. indica (13.34) showing their tolerance ability in response to particulate matter and heavy metals. Aforementioned plant species can be used to further investigate how plants and pollutants interact and for enhancing potential phyto-control methods for minimizing air pollution.