IMPACT OF SULPHUR DIOXIDE (SO2) – AS A POLLUTANT ON THE GROWTH OF SUNFLOWER (Helianthus annuus L. cv. PAC-36)

Abstract

Among the various air pollutants, sulphur dioxide (SO₂) is one of the principal contaminants. In the gaseous form it is called as primary pollutant but when it binds moisture from the air and forms aerosols of sulphuric- and sulphurous acid which are deposited as acid rain, it acts as secondary pollutant. Plants after exposure to SO₂ show altered growth patterns. The oil-yielding cultivar cv.PAC-36 of Helianthus annuus L.(family Asteraceae) on fumigation with four cumulative doses 2612, 3265, 3918 and 4571µg  m^-3 of SO₂ manifested a decline in the length, fresh weight and dry weight of shoot, root and whole plant respectively. These growth attributes were studied at 30^th, 50^th, 70^th and 90^th day of the fumigated cultivar along with a control set. The concentration of pollutant and duration of exposure measure the severity of injury in the fumigated plants. The cultivar studied exhibit acute injuries in advanced stages of growth with higher concentrations and cumulative doses, i.e., the damage caused by 2612 and 3265µg m^-3 SO₂ were lesser in comparison to 3918 and 4571µg m^-3 SO₂ and the pollutant produced more appreciable effects on 90d old plants than 70d, 50d and 30d old plants.