Peroxidase Activity as an Indicator of SO2- Tolerance in Crop Plants

Effect of different SO₂ concentrations on the peroxidase activity in the leaves of three economically important plant species, viz., Vigna radiata (Mung bean), Solanum esculentum (= Lycopersicon esculentum) [Tomato] and Zea mays (Maize) was studied. Controlled fumigation experiments were carried out using three different treatments of SO₂ : T-1 = 0.05 ppm(134.0µg m^-3 SO₂) [x 4h], T-2 = 0.1 ppm(268.0 µg m^-3 SO₂) [x 2h] and T-3 = 0.2 ppm(536.0 µg m^-3 SO₂) [x 1h] for 60 days. Although the peroxidase levels in controls were highest in Z.mays, followed by V.radiata and S.esculentum, it was S.esculentum which recorded maximum increase in peroxidase activity after SO₂ fumigation, followed by V.radiata and Z.mays. Enhanced peroxidase activity is indicative of greater tolerance toSO₂ stress.