Physiochemical screening of road avenue plants in better landscape management of highly polluted urbanized city (Lahore), Pakistan

Lahore has been consistently ranked as the world's most polluted city. Because of combative ideas to construct highways, underpasses and flyovers, Lahore had lost a remarkable percentage of its tree cover over the past 15 years. The present study focuses on the outcomes of rapidly increasing air pollution on roadside vegetation. In current study, species such as <i>Alstonia scholaris</i> L.<i>, Bougainvillea spectabilis</i> Willd., <i>Dalbergia sissoo</i> Roxb<i>. Eucalyptus globulus</i> Labill., <i>Ficus virens</i> Aiton, <i>Ficus benjamina</i> L.<i>, Ficus religiosa</i> Linn.<i>, Morus alba</i> L.<i>, Murraya paniculata</i> L<i>., Putranjiva roxburghii</i> Wall., <i>Polyalthia longifolia</i> Sonn., <i>Rubia tinctorum</i> L. found on the seven busiest roads of Lahore were selected (on the basis of traffic densities) for biomonitoring. These plants were selected due to their prevalence and commonly occurrence on these selected roads. Variation on biochemical parameters like chlorophyll a, b, total chlorophyll content & carotenoids and physiological parameters like stomatal conductance, transpiration rate and photosynthetic rate were found in triplicate. By analyzing these parameters quality of air and health of plants can also be assessed. In this study the dust load was maximum on the leaves of <i>Alstonia scholaris</i> L. (0.02 ± 0.005), <i>Ficus religiosa</i> Linn. (0.02 ± 0.003), and <i>Morus alba</i> L<i>.</i> (0.02 ± 0.003) Reduction in chlorophyll was noticed in <i>Alstonia scholaris</i> L. (0.44 ± 0.22) and <i>Polyalthia longiflia</i> Sonn. (0.41 ± 0.22) while the chlorophyll concentration of <i>Eucalyptus globulus</i> Labill. (0.71 ± 0.16), followed by <i>Ficus benjamina</i> L<i>.</i> (0.80 ± 0.25), <i>Ficus religiosa</i> Linn<i>.</i> (0.81 ± 0.30), <i>Ficus virens</i> Aiton<i>.</i> (0.64 ± 0.22), <i>Morus alba</i> L. (1.80 ± 0.27) and <i>Putranjiva roxburghii</i> Wall<i>.</i> (2.55 ± 0.43), was higher at polluted sites<i>.</i> The reduction in carotenoid content was found in <i>Murraya paniculata</i> L. (4.12 ± 2.18) while it was highest in <i>Eucalyptus globulus</i> Labill. (9.12 ± 0.71) Due to the pollution stress the changes in photosynthetic rate of <i>Alstonia scholaris</i> L<i>.</i> (25.36 ± 13.10), <i>Bougainvillea spectabilis</i> Willd. (34.37 ± 19.92), <i>Dalbergia sissoo</i> Roxb. (28.23 ± 11.25), <i>Murraya paniculata</i> L. (26.80 ± 7.75), <i>Polyalthia longifolia</i> Sonn. (42.27 ± 22.87), and <i>Rubia tinctorum</i> L. (30.60 ± 4.07) was observed. The current research distinctly signifies <i>Eucalyptus globulus</i> Labill., <i>Ficus benjamina</i> L., <i>Ficus religiosa</i> Linn., <i>Ficus virens</i> Aiton., <i>Morus alba</i> L. and <i>Putranjiva roxburghii</i> Wall., have capability to hold on the stress triggered by roadside pollutants. The findings are useful to urban green space landscapers in harsh climates as they choose appropriate species that can offer a variety of ecosystem services, such as resistance to air pollution and lowering of temperature without compromising plant survival.