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.