| Summary: In this study, the effects on antioxidant system and photosynthetic yield were investigated in drought tolerant and sensitive maize varieties that were subjected to drought stress after polyamine (PA) pre-treatment during leaf rolling. Firstly, leaf rolling degrees of maize varieties pretreating 0.1 mM Put and 0.1 mM Spm during drought stress were found to be delayed by PAs.. It was determined that leaf water potential, leaf relative water content (%), antioxidant enzyme activities (SOD, CAT, GPX, APX, DHAR, MDHAR and GR) and non-enzymatic ascorbate (ASC) and reduced glutathione (GSH) increased, and lipid peroxidation and content of H2O2 decreased in tolerant and sensitive maize varieties that were pre-treatmented Put and Spm during leaf rolling. Also, it was found to increase content of photosynthetic pigment, chlorophyll fluorescence parameters, some photosynthetic gas exchange parameters, and amounts of endogenous PAs, and to decrease NPQ be parameters of chlorophyll fluorescence. When leaf rolling was prevented as mechanical, antioxidant system and photosynthetic activity was determined to be inhibited in the both maize varieties, especially in sensitive maize. It was found that exogenous PA treatments increased the level of endogenous PA, and that application of inhibitors of PA biosynthesis pathway decreased endogenous PA levels. As a result, it was concluded that PAs pre-treatment during leaf rolling is effective in increasing antioxidant system and photosynthesis and improving drought tolerance in tolerant and sensitive maize varieties, in particular, the tolerant variety under drought conditions.
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