Changes in Carbohydrate Levels in Red Kidney Bean (Phaseolus vulgarisL.) Exposed to Sulphur Dioxide

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Abstract
Red kidney bean (Phaseolus vulgaris L.) was exposed to various concentrations of SO2 for 24 h (16 h light/8 h dark photoperiod) with continuous monitoring of photosynthetic and respiratory activity. Plants were harvested at the end of the dark period into samples of mature and immature leaf tissue, stems, and roots for determination of sugar and starch levels. In all tissue samples the levels of total sugars were increased by exposure to the lower concentrations of SO2, but decreased by the higher concentrations. Starch levels in leaves followed a similar trend. Increases in sugar and starch levels preceded symptoms of visible injury. Decreasing rates of photosynthesis were correlated with increasing rates of respiration, the occurrence of visible injury, and the depletion of sugar and starch levels.