Impact of air pollution on reproductive biology of plants: Mechanisms and consequences

• Pollution induced environmental stress can disrupt plant phenology, floral morphogenesis. • Structural abnormalities in anthers, tapetal layers, pollen grains and reduced pollen viability are common under pollution exposure. • Pollutants can affect floral morphology, bud abortion, floral scents and nectar interfering pollinator attraction. • Proximity to pollution sources results in reduced fruit set & seed quality (number and weight). Reproductive fitness is paramount to a plant’s ecological and evolutionary processes, establishing species persistence, population dynamics, and ecosystem stability. The consequences of a plant’s reduced reproductive fitness extend beyond a single individual and can lead to population decline, genetic erosion, and subsequent impairments to ecosystem services. Air pollution is a critical environmental stressor that adversely impacts plant reproduction. To effectively mitigate the detrimental effects of air pollution on plant reproduction, a comprehensive understanding of these complex interactions is essential. This review comprehensively summarizes the harmful effects of airborne pollutants on multiple stages of plant reproduction. Pollutants have strong effects on phenology either by delaying or by advancing the phenoevents, floral morphology, flower production and increased bud abortion rate. With regard to male fitness in pollutant rich areas, it has been well established that the anther wall, pollen morphology, pollen production, and pollen viability are affected due to pollutant exposure. Only a handful of studies have elucidated the effect of air pollutants (PM, O 3 and SO 2 ) on pollen germination and tube growth in the stylar region. Floral cues and incentives also get compromised in polluted areas. Consequently, these affect plant-pollinator interactions thereby hindering successful fertilization and yield. Discrete effects of SO₂, NO₂ and O 3 have significant negative correlations with yield in agroecosystem such as fruit-set, seed number and seed weight. The present review provides an insight into the influence of various air pollutants on plant reproduction, acting as a compendium of all work conducted thus far, besides also highlighting lacunae in the field that require attention.