The study was performed to determine as to whether antioxidant potential (enzymatic and non-enzymatic antioxidants) as well as some other attributes could be used as potential drought resistance markers in two maize lines (B 73 and MO 17). Under water deficit conditions, growth traits, relative water content (RWC), chlorophyll a, total chlorophyll and carotenoids as well as grain yield decreased significantly in both lines compared to those under control conditions. In contrast, water deficit caused a significant increase in the activities of superoxide dismutase (SOD) and catalase (CAT) isozymes as well as levels of glycine betaine (GB), proline and malondialdehyde (MDA), whereas total phenolics, total soluble protein, H 2 O 2 , chlorophyll b, chlorophyll a/b ratio, anthocyanin and peroxidase (POX) isozyme activity remained unaffected in both maize lines. Although water deficit stress induced oxidative stress in both maize lines, the enzymatic and non-enzymatic antioxidants and key organic osmolytes increased significantly in both maize lines. For example, SOD isozyme activities, and GB and proline contents were considerably greater in relatively drought resistant MO 17 than those in relatively drought sensitive B 73. However, in contrast, CAT activity was higher in B 73. Overall, SOD isozyme activities, and GB and proline contents were found to be potential biochemical indicators of drought resistance in the two maize lines used in the present study.

Fusarium verticillioides is one of the most common phytopathogenic fungi affecting maize production, worldwide. The early identification of F. verticillioides infection in maize could be helpful to prevent the spreading of the fungus. Therefore, this study represents the use of chlorophyll fluorescence parameters to identify F. verticillioides infection in maize. Chlorophyll a fluorescence of control and F. verticillioides infected plants showed a typical polyphasic OJIP transient curve in both MO17 and B73 lines. Infected plants from both maize lines showed a different pattern of OJIP transient curve when compared to the control plants, respectively. This indicated that F. verticillioides had an effect on the photosynthesis of infected maize plants. This study demonstrated the importance of parameters such as: the activity of the watersplitting complex on the donor side of PSII (F v /F 0), minimum fluorescence (F 0), maximum fluorescence (F m), and absorption flux per one active reaction center (ABS/RC) to identify F. verticillioides infection in maize.

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