This study investigated the effects of foliar application of normal and nanoparticles of zinc oxide (ZnO) on the growth, proline content, and some antioxidant enzyme activities of sunflower cultivars at different salinity levels. Treatments included five cultivars (Helianthus annuus L. cvs. Alstar, Olsion, Yourflor, Hysun36, and Hysun33), two salinity levels (0 and 100 mM NaCl), and three foliar applications (none-sprayed, ZnO normal and nanoparticles at a rate of 2 g/L). Olsion showed the

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... st proline content and superoxide dismutase activity (SOD) among the studied cultivars under saline condition. Foliar spray of ZnO improved SOD activity and shoot dry weight of sunflower. Nanoparticles of ZnO had positive effect on biomass production of sunflower plants compared to the normal form. According to the result, Olsion and Hysun33 cultivars were suitable for saline conditions, whereas Hysun36 was appropriate for normal condition.