Assessment of the variability in response of radish and brinjal at biochemical and physiological levels under similar ozone exposure conditions.

The present investigation was done to evaluate the effects of ambient air pollutants on physiological and biochemical characteristics of radish (Raphnus sativa L. var. Pusa Reshmi) and brinjal (Solanum melongena L. var. Pusa hybrid-6) plants grown in open-top chambers with filtered (FCs) and non-filtered (NFCs) treatments at a suburban site in Varanasi, India. Eight hourly mean concentrations of 11.8, 20.8, and 40.8 ppb for SO2, NO2, and O3, respectively, were recorded. O3 was the most significant pollutant affecting the plant performance. Photosynthetic rate and stomatal conductance declined in both the test plants in NFCs as compared to FCs. Lipid peroxidation was higher in NFCs, but the increase was more in radish compared to brinjal. The constitutive levels of the antioxidants as well as their increments upon O3 exposure were of higher magnitude in brinjal as compared to radish. Reduction in Fv/Fm ratio of the plants in NFCs was a regulatory mechanism to cope with the inefficiency of Calvin cycle. The data indicate that O3 triggered the protective mechanisms in plants which resulted in increments in enzymatic and non-enzymatic antioxidants of O3-exposed plants. The variability of the magnitude of responses in radish and brinjal due to O3 stress suggests that radish is more susceptible to ambient O3 injury compared to brinjal.