Effects of Acid Rain on Plant Physiology

Acid rain, characterised by wet or dry deposition with pH values below 5.6, exerts profound effects on plant physiological processes. Foliar exposure to acidic precipitation damages cuticular layers and disrupts stomatal function, leading to impaired gas exchange and reduced photosynthetic efficiency. In the rhizosphere, lowered pH mobilises aluminium and other toxic metals, inhibiting root elongation and nutrient uptake. Deficiencies of essential cations such as calcium and magnesium compromise chlorophyll biosynthesis and destabilise thylakoid membranes, intensifying photoinhibition under high irradiance. Acid-induced oxidative stress arises from overproduction of reactive oxygen species, prompting the activation of antioxidant enzyme networks. At the molecular level, acid exposure modulates expression of genes governing proton transport, secondary metabolite synthesis and stress-responsive transcription factors. Species-specific responses reflect variations in tolerance mechanisms, with implications for forest productivity, crop resilience and ecosystem stability under shifting emission profiles and climate conditions.

Research from Nature Portfolio

Recent studies have provided mechanistic insights into how acid deposition reshapes cellular and molecular processes. A study in a leading plant journal elucidated the regulatory role of proton transporters in maintaining cytosolic pH under acidic precipitation, showing that upregulation of plasma membrane H+-ATPases sustains root growth and mitigates aluminium toxicity. Complementary work in a communications journal employed transcriptome profiling in a model dicot to identify networks of genes controlling antioxidant enzyme synthesis and phenolic metabolite accumulation, demonstrating that induction of secondary metabolite pathways confers protection against oxidative damage. Another report integrated physiological assays and chlorophyll fluorescence imaging to reveal that moderate acid inputs can trigger acclimation responses in canopy leaves—partially stabilising photosystem II efficiency through enhanced repair—whereas severe acidity causes irreversible photoinhibition.

Effects of Acid Rain on Plant Physiology publication trend

The graph below shows the total number of articles in effects of acid rain on plant physiology across all publications each year (not limited to Nature Index journals).

Technical terms

Stomatal conductance: Rate of CO₂ uptake and water vapour loss through leaf stomata, indicating gas exchange capacity.

Reactive oxygen species (ROS): Highly reactive molecules produced under stress that can damage lipids, proteins and nucleic acids.

H⁺-ATPase: Proton pump in the plasma membrane that transports H⁺ ions to regulate intracellular pH and turgor.

Chlorophyll fluorescence: Emission of light by chlorophyll molecules, used to assess photosystem II efficiency and photoinhibition.

Phenolic compounds: Secondary metabolites with antioxidant functions that scavenge reactive oxygen species.

Photoinhibition: Damage to the photosynthetic apparatus, particularly photosystem II, under excess light or environmental stress.

References

1. Complex effects of different types of acid rain on root growth of Quercus acutissima and Cunninghamia lanceolata saplings. Ecological Processes (2022).
2. Morphological, Physiological and Photophysiological Responses of Critically Endangered Acer catalpifolium to Acid Stress. Plants (2021).
3. Effects of Acid Rain Stress on the Physiological and Biochemical Characteristics of Three Plant Species. Forests (2023).