This investigation was conducted to evaluate the effects of post-harvest application of silver nanoparticles (N-Ag) and dark storage on plastid pigments, petal abscission, lipid peroxidation and activities of ascorbate peroxidase (APX) and guaiacol peroxidase (POD) in pelargonium cultivars ‘Blue Wonder’ and ‘Anthony’. N-Ag was applied as foliar spray in concentrations 0, 20, 40, 60 and 80 mg·cm-3 and then the plants were stored for 5 days in a growth chamber in darkness at temperature 20±2 °C and relative humidity 65%. The results revealed that after dark storage the petal abscission of cv. ‘Blue Wonder’ increased up to 40% but significantly decreased in plants treated with 60 mg·cm-3 of N-Ag. Cultivar ‘Anthony’ showed lesser petal abscission than ‘Blue Wonder’, namely 25% in control and 4% after treatment with 60 mg·cm-3 N-Ag. In both cultivars, treatment with N-Ag resulted in higher contents of leaf chlorophylls and carotenoids in comparison to untreated control. In response to treatments with 20-60 mg·cm-3 N-Ag, the activity of APX and POD was higher at the end of 5 days storage period than in the control plants, which coincided with improved post-harvest performance of both pelargonium cultivars. The enhancement of enzyme activities indicated possible beneficial effect of the applied treatment on alleviation of dark storage-induced oxidative stress. Also, in both cultivars, MDA content decreased significantly with the increase of N-Ag concentration up to 60 mg·cm-3 and then a rapid increase at 80 mg·cm-3 followed. It is concluded that treatment with silver nanoparticles is effective for preventing dark storage-induced petal abscission of pelargonium.
