Role of antioxidative defense system in amelioration of cadmium-induced phytotoxic effects in germinating seeds of maize (

Abstract

Context Anthropogenic activities are increasing Cd concentration in soil and environment that limits seed germination capacity and causes poor seedling establishment. Aims The effect of different Cd concentrations on seed germination and seedling growth of two maize cultivars (C-20 and EV-1098) was tested in this study. Methods Maize seeds were sown in Petri dishes lined with double filter paper. The seedlings were grown in a growth chamber, applied with different Cd concentrations (0, 2, 4, 6, 8 and 10 μM), and harvested 12 days after germination. Key results Seeds applied with higher levels of Cd showed a significant decrease in seed germination percentage (GP), seed emergence index (EI) and germination energy (GE). A significant delay in seed germination was observed at the highest Cd treatment in terms of increased mean emergence time (MET), days to 50% germination (T 50) and coefficient of uniformity of emergence (CUE). A marked decline in leaf K, Ca, Na, and P was observed, whereas root K, Ca and P increased with an increase in external Cd concentration. The roots and leaves of maize C-20 showed greater activities of superoxide dismutase (SOD) than did those of EV-1098. In contrast, peroxidase (POD) activity was reasonably high in roots and leaves, whereas catalase (CAT) was high only in roots of EV-1098. Non-enzymatic antioxidants such as phenolics and ascorbicacid (AsA) also significantly increased, accompanied with substantially lowermalondialdehyde (MDA) contents in the roots and leaves of EV-1098 than of C-20. Conclusions The differential modulation of the activities of enzymatic and non-enzymaticanti-oxidative defense system in roots and leaves played a critical role intolerance of both cultivars to Cd stress. Implications The findings of this study are helpful in improving seed germination capacity and seedling growth of maize in Cd contaminated soils.