HomeNewsCustard apple tree more tolerant to air pollution

Custard apple tree more tolerant to air pollution

A new study to understand the pollution tolerance levels among trees in Pune has concluded that Annona squamosa (custard apple) and Delonix regia (a kind of flowering plant) are relatively more tolerant to air pollution, contributed mainly by vehicular emissions around Aundh and Savitribai Phule Pune University campus.

The Pune University circle along Ganeshkhind Road is one of the busiest junctions in the city. It is estimated that over 1 lakh vehicles pass through this junction every day, making it one of the highly-polluted localities in Pune.

A joint study, led by researchers at the Environment Department, Savitribai Phule Pune University (SPPU) and Indian Institute of Tropical Meteorology (IITM), found that Ficus religiosa (commonly referred as sacred fig), Tamarindus indica (tamarind) and Ficus benghalensis (banyan) were highly sensitive to particulate matter (PM), stressing that trees not be planted as part of any pollution mitigation programmes.

In the study, accepted recently in the journal Environment Challenges, researchers studied trees along the 3-km stretch of Aundh Road and those standing on the SPPU campus, earmarked as a polluted and a non-polluted area, respectively. Leaves of these trees were collected to understand the concentration of chlorophyll from these two locations. In addition, levels of sulphur dioxide and nitrogen dioxide, too, were monitored at these sites.

Past studies have stated that about 60 per cent of the air quality worsens, mainly due to automobile emissions, apart from industrial, biotic sources and others. Even among vehicles, the emissions are heterogenous and depend on the fuel type, engine stroke and other factors. For instance, diesel engine vehicles emit smoke along with high concentration levels of nitrogen dioxide. Vehicle fumes using gasoline emit carbon monoxide, nitrogen dioxide, sulphur dioxide and particles of aldehydes.

The researchers from Fergusson College, Women’s College of Home Science, Loni and DKTE Textile and Engineering Institute, Ichalkaranji, calculated the Air Pollution Tolerance Index (APTI) of these tree varieties. Based on the biochemical indicators, the APT index suggests a plant’s ability to counter air pollution. Such tolerant plants are often used for the development of green belts across busy roads. The air pollution response of each plant varies with species and location.

It was found that the flowering tree and custard tree possessed the highest APTI at 37.28 and 23.02, respectively. The APTIs of the three sensitive trees were below 15.

“Higher air pollution has a significant effect on select roadside trees. Trees like Annona squamosa and Delonix regia can be used as carbon sink and must be planted along the roadside,” the study highlighted.

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