Cengiz Kaya - Harran University, Faculty of Agriculture, Department of Soil Science & Plant Nutrition, Şanlıurfa, Turkey
Muhammad Ashraf - Pakistan Science Foundation, Islamabad, Pakistan
Osman Sonmez - University of Erciyes, Faculty of Agriculture, Department of Soil Science & Plant Nutrition, Develi, Kayseri, Turkey

A glasshouse experiment was conducted to appraise the influence of combined nitric oxide (NO) and thiamin (TA) on oxidative defense system and some key physiological attributes in two maize cultivars (DK 5783 and Apex 836) stressed with 0 (control) or 100 mM NaCl. Of six NO and TA levels used in the initial germination experiment, 2 levels of combined NO and TA (3 +100 or 6+ 125 mg l-1 respectively) were chosen for subsequent studies as seed soaking or as a spray to seedlings. Salinity resulted in rising leaf free proline content and osmolality, but in a decrease in plant dry biomass and maximum fluorescence yield (Fv/Fm) in cultivars. Both modes of applied NO and TA were found to be effective in alleviating the adverse effects of NaCl on shoot growth. Salt stress resulted in enhancing leaf Na+, but reducing leaf K+ and Ca2+ in plants. Both modes of application of NO and TA resulted in increased Ca2+ and K+ contents, but decreased those of Na+ in salt stressed maize plants. Salt stress caused the enhanced accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Salinity promoted the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in maize. The growth improvement in maize plants due to exogenously-applied NO and TA in combination was found to be due to decreased leaf Na+, H2O2 and MDA levels, and altered activities of SOD, CAT, and POD as well as improved maximum fluorescence yield under saline stress.

Maize, Nitric oxide, Thiamin, Salt tolerance, Oxidative stress