Atmospheric particle retention capacity and photosynthetic responses of three common greening plant species under different pollution levels in Hangzhou

Abstract

The retention capacities and photosynthetic response to different-sized particulate matter in plants are very important indicators for urban green plant species selection. A large number of studies have been reported on the particulate matter retention capacities of plants, but few reports have been reported on the photosynthetic response of plants after particulate matter retention. In this study, we investigated the capacities of Rhododendron x pulchrum Sweet, Osmanthus fragrans Lour. and Photinia x fraseri Dress to retain atmospheric particles of different sizes and their photosynthetic gas exchange capacity in autumn and winter of 2017 at a freeway toll station and on a university campus. The results showed that the retention capacities of the three plant species were in the order R. pulchrum > O. fragrans > P. fraseri. The total suspended particles (TSPs) absorbed by R. pulchrum at the freeway toll station was the highest (autumn: 371.22 μg cm−2; winter: 177.11 μg cm−2), while the TSPs absorbed by P. fraseri at the campus was the lowest (autumn: 36.13 μg cm−2; winter: 41.50 μg cm−2). Plant surface retention (sPM) accounted for more than 60% of TSPs. Large particulate matter (10–100 μm) in sPM and wPM accounted for 52.17–9.60% and 45.36–72.20%, respectively. In winter, the proportion of fine particulate matter (0.2–2.5 μm) of sPM was significantly higher than that in autumn. Photosynthetic gas exchange capacity of plants, especially stomatal conductance (Gs), was significantly reduced by particulate pollution. There was a negative correlation between plant dust retention and photosynthetic gas exchange capacity. The amount of PM2.5 retained by plants was negatively correlated with the net photosynthetic rate (Pn). The photosynthetic gas exchange capacity of P. fraseri was the least affected under different particulate pollution levels, and this species was best able to adapt to growing in a more polluted environment. Keywords: Particulate matter, Photosynthetic responses, Plant dust, Rhododendron x pulchrum Sweet, Osmanthus fragrans Lour., Photinia x fraseri Dress