Priming with zinc oxide nanoparticles improve germination and photosynthetic performance in wheat.

The present study is the first attempt to demonstrate the beneficiary effects of seed priming with zinc oxide nanoparticles (ZnO NPs) in wheat cultivar H-I 1544. Wheat seeds primed with ZnO NPs (10 mg/L) showed a significant positive influence on seed germination performance and vigour index as compared to unprimed (control) and hydroprimed seeds. Furthermore, nanopriming also enhanced seed water uptake resulting in enhanced α-amylase activity. Content of photosynthetic pigments in nanoprimed plants (chlorophyll a, chlorophyll b and total chlorophyll content) was significantly enhanced. Chlorophyll a fluorescence measurements were performed 30 days after cultivation of nanoprimed seeds to investigate the effect of nanopriming on plant photosynthetic performance. Results suggested that ZnO NPs affects the overall primary photochemistry by enhancing the performance of water splitting complex at donor side of PSII (Fv/Fo). The numbers of active reaction centres (RC) per chlorophyll molecule were increased in nanoprimed plants followed by increase in the absorption (ABS), efficiency of excitation energy trapping (TR) and electron transport (ET) from active reaction centres. The impact of nanopriming on oxidative status of plants was also studied by measuring the activity enzymes like peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and degree of lipid peroxidation. A prominent decrease in the activity of these enzymes was observed which may be attributed to low reactive oxygen species (ROS) levels in nanoprimed plants as compared to control. This is the first report showing ZnO NPs as a promising seed priming agent to improve germination as well as photosynthetic performance of wheat seeds.