The relationship between SO₂ exposure and plant physiology: A mini review

Air pollutants are emitted from various sources into the atmosphere. During winter, greenhouses are heated by the burning of fuel in heating systems, which creates sulfur dioxide (SO₂) that can be detrimental to plant growth and human health. However, there is a poor understanding of the comprehensive effects of SO₂ on crops in a greenhouse environment. Therefore, this review aimed to summarize the impacts of greenhouse heating system-derived SO₂ on the physiological, morphological, and biochemical responses of plants. In general, plant SO₂ exposure has a negative effect on these processes. An initial decline in physiological activities appears several days following SO₂ exposure. Morphological and biochemical activities are also negatively affected by extensive SO₂ exposure. However, since sulfur is an essential nutrient for plant growth, low-level SO₂ exposure has a positive impact on plants. Atmospheric SO₂ is taken up by the plant via the stomata, after which it is assimilated and used to synthesize sulfur-containing amino acids, such as methionine and cysteine. Sulfur-containing compounds are crucial for plant growth, and various physiological and biochemical processes. It was concluded that SO₂ is a significant greenhouse pollutant, especially for crops.