Air pollution may alter reproductive dynamics/efficacy in plants: correlative evidences from an urban sprawl in Eastern Indo-Gangetic plain

For urban ecosystem, the understanding of plant responses and behavioral pattern to prevailing stresses is critical. This study aims to evaluate the reproductive behavior of 40 roadside plants, including trees, shrubs, and herbs, to higher air pollution load for three successive years (i.e.—2017, 2018, and 2019) in an Indo-gangetic urban sprawl. The mean surface concentration of three gaseous pollutants (O₃, NO₂, and SO₂) and one particulate matter with aerodynamic diameter ≤ 1 µm (PM₁) was found to be highest at the polluted sites during all seasons. Though, there is no prescribed national standard for total atmospheric deposition; but, it was found significantly higher in all the seasons at the urban sites. According to obtained results, the natural pollen viabilities in all the plant species decreased to 10% significantly earlier at the urban sites. The seed numbers, weight, viability, and in-vivo germinations were also reduced significantly under higher air pollution load. The K-means cluster including all obtained data demonstrated a major group of 36 plants followed by two out groups of 2 plants each. Exceptionally, few plants, such as M. indica, R. communis, S. sisymbrifolium, M. azedarach, H. indicum, J. gossypifolia, S. tora, A. indicum, and C. gigantea, showed improved or unaffected responses in some of the reproductive parameters under higher air pollution load. Altogether, the obtained responses of all these plant species might be useful to understand the reproductive strategies, and can be utilized towards screening of effective species for sustainable urban green space development.