Role of Biochemical and Biophysical Characteristics in Management of O3 Injury in Plants Through Soil Nutrient Amendments

Abstract

The present study focuses on mitigative measurements adopted to manage ozone (O3 ) stress by application of different doses of nutrient (N, P, K) treatments. Two cultivars of maize (Zea mays L. var HHM-1 and Malviya hybrid2) growing under ambient O3 stress conditions were treated with three doses of nutrients (NPK); recommended (N1 ), 1.5x recommended (N2 ) and 2x recommended (N3 ) in near natural condition. The antioxidant pool, secondary metabolites, photosynthetic efficiency and gas conductance parameters were assessed. Results of our experiment suggest that the plants treated with nutrients responded better than the plants without nutrient, which served as control. Increased antioxidant activities in both the maize cultivars upon nutrient treatment resulted in decline of O3generated superoxide radicals and H2O2 contents, indicating a reduction in O3 stress. It was observed that the antioxidant response upon treatment was more prominent in HHM-1, as compared to MH-2, in which major proportions of antioxidant stimulations were observed during the vegetative period only. SOD and CAT played an important role in defining the plant’s defense and regulating the SOR and H2O2 contents in both the maize cultivars at both vegetative and reproductive stages. The results of the present experiment clearly suggest that nutrient amendments can be effectively used in partially mitigating ambient ozone stress, however more experimentation with different crop varieties is required to prove the expediency of nutrient amendments.