Question

Destruction of chlorophyll of plants, premature leaf fall and yellowing of leaf is caused by excess of ......... in atmosphere.

• A. CO${}_2$
• B. SO${}_2$
• C. CO
• D. NO${}_2$

Answer 1

The correct option is B SO${}_2$

In $S{O}_2$ pollution, plants show initial reduction of photosynthesis and increased respiration. The gas reduces stomatal opening and thus causes general water stress in plants. Most common visible symptom of $S{O}_2$ injury is water-soaked appearance of leaves, which later become necrotic changing into brown spots. In some species, characteristic intraveinal chlorosis is caused. In general, $S{O}_2$ pollution results in abscission of older leaves and tip necrosis in flower and sepals.