The Retention Capacity And Physiological Response Of Three Common Greening Plant Species Under Different Pollution Levels

Particulate matter?PM?has become a major resource air pollutant in many cities.More and more attention has been paid to plants as natural filters of urban atmospheric particulate matter.The retention ability and photosynthetic response to different-sized particulate matter in plants are very important indicators for urban green tree species selection.A large number of studies have been conducted on the capacities of plant particulate matter retention,but few reports have been reported on the photosynthetic and biochemistry 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 response in different seasons at a freeway toll station and on a university campus in Lin'an from July,2017 to May,2018.The results showed that:?1?The retention capacities of the three tree species were in the order R.pulchrum>O.fragrans>P.fraseri.The dust retention ability of P.fraseri is least affected by season.The PM retentioned in plants are mainly concentrated on leaf surface and large particles.PM retentioned on the leaf surface accounted for more than 50%of the total PM retentioned;The proportion of large particles in the surface PM of plant leaves was more than 45%;The particles retentioned in plant wax layer are mainly concentrated in large and coarse particles.The capacities of plants retention PM is reduced when they experience sustained high temperatures.?2?Particulate matter pollution has a negative effect on the P_nmax,L_CP,L_SP of plants.Particulate matter blocking plant stomata leads to a decrease P_n of plant,fine particulate matter is an important factor affecting plant photosynthesis.?3?Particulate matter pollution can affect the activity of plant protective enzymes in plants,the T-SOD activity did not change much;the freeway POD activity,the content of MDA,the content of protein was significantlyhigher than the campus;soluble sugar contents showed different trends with different plants.In conclusion,among the three common greening tree species,P.fraseri has the strongest stress resistance and R.pulchrum is the most sensitive to particle pollution stress.R.pulchrum is suitable for planting in places with pollution to improve ambient air quality by retained more particulate matter.