Effect of Nanometals and Pulsed Electric Field (PEF) on the Germination Capacity of Seeds and Antioxidative Properties of Seedlings of Sunflower

The increasing integration of physical and nanotechnological treatments in agriculture has unlocked new possibilities for enhancing seed performance and the functional properties of seedlings. This study aimed to determine the effect of the coupled use of pulsed electric field (PEF) and the soaking (coating) of sunflower seeds in metal nanoparticles (AgNP and CuNP) on their germination capacity and on the stem and root length, content of pigments (chlorophyll <i>a</i>, chlorophyll <i>b</i>, carotenoids), color profile, and antioxidative properties (FRAP, polyphenols, TPC, ABTS, and DPPH) of sunflower seedlings. The study results enable the drawing of explicit conclusions that the higher PEF energy applied (5.5 kJ kg^-1) and seed treatment with nanoparticle solutions, in most cases, diminished the germination capacity of sunflower seeds (from 3.50 to 44.11%) compared to the control samples. A decreased seedling stem length was determined at both PEF energy levels tested, i.e., 1 kJ kg^-1 and 5.5 kJ kg^-1, with the values obtained being 11.86% to 46.14% lower compared to the respective control samples. The root length of the seedlings decreased as well, i.e., by 7.34 to 41%. The content of chlorophyll <i>a</i> (chl <i>a</i>) increased in the seedlings from all experimental variants compared to the control, whereas that of chlorophyll <i>b</i> (chl <i>b</i>) decreased by 3.24 to 7.86% in the control variant with PEF and CuNP. The FRAP value, total content of polyphenols, and TPC ranged from 10.20 to 12.95 (mg TE g^-1 DM), from 42.23 to 49.19 (mg GAE g^-1 DM), and from 20.20 to 23.90 (mg GAE g^-1 DM), respectively, and showed an upward trend compared to the control samples. The results of this study indicate that further research is needed to understand how the analyzed treatments affect seedling growth and demonstrate reduced germination capacity and enhanced antioxidant activity due to the synergistic effect of a high PEF and nanoparticle solutions.