Metabolic effects of sulfur dioxide fumigation on Mangifera indica plants.
Farooq M., Hans R. K.
Author Affiliation: Photobiology Laboratory, Industrial Toxicology Research Centre, Post Box No. 80, Mahatma Gandhi Marg, Lucknow-226 001, India.
Bulletin of Environmental Contamination and Toxicology 63 : 774-781
Abstract : In lab. tests, M. indica plants were exposed to 0.8, 2.5, 6.5 or 8.0 ppm sulfur dioxide (SOČ) for 4 h and observed for 48 h after exposure for the appearance of visible foliar injury. No visible symptoms were observed on foliage of plants 48 h after exposure to 0.8 ppm SOČ, while interveinal necrosis was observed after exposure to 2.5 ppm. At 6.5 ppm, symptoms were more severe and at 8.0 ppm chlorotic symptoms developed immediately, covering 90% of the leaf area. Levels of sulfur in the leaf tissues increased with increasing exposure, and a number of metabolic changes were observed. Protein content and levels of starch, total free sugars and reducing sugars were higher in exposed plants and phenolic content increased gradually with increasing exposure. Chlorophyll content also increased with increasing exposure, but no change was observed in pheophytin content. Peroxidase activity increased with increasing SOČ conc., while acid phosphatase activity decreased significantly at 2.5 and 6.5 ppm SOČ. It is concluded that metabolic alterations are initiated at SOČ conc. below those causing visible injury, and that mango can be categorised as a pollution sensitive plant.