Environmentally benign synthesis of phytochemicals-capped gold nanoparticles as nanopriming agent for promoting maize seed germination Wuttipong Mahakham a , Piyada Theerakulpisut c, ⁎, Santi Maensiri b , Santi Phumying b , Ajit K. Sarmah a, ⁎ a Department of Civil and Environmental Engineering, Faculty of Engineering, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand b School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand c Salt-tolerant Rice Research Group, Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand HIGHLIGHTS • GNPs were successfully synthesized using galanga rhizome extracts. • Phytochemicals-capped GNPs were non-toxic and biocompatible. • Priming with GNPs can boost germina- tion of maize aged seeds. • Nanopriming approach is promising technology for sustainable agriculture. GRAPHICAL ABSTRACT abstract article info Article history: Received 20 May 2016 Received in revised form 18 August 2016 Accepted 18 August 2016 Available online xxxx Editor: D. Barcelo Application of nanotechnology in agriculture is moving towards to improve the cultivation and growth of crop plants. The present study is the first attempt to propose a simple, yet cost-effective and ecofriendly synthesis of phytochemicals-capped GNPs using rhizome extract of galanga plant at room temperature. The synthesized GNPs were characterized by various characterization techniques. To promote the green nanotechnology applica- tions in agriculture, GNPs solution at environmentally realistic dose (5 to 15 ppm) as nanopriming agent was used to activate the germination and early seedling growth of maize aged seeds. Priming with 5 ppm GNPs showed the best effects on promoting emergence percentage (83%) compared to unprimed control (43%) and hydroprimed groups (56%). Seed priming at both 5 and 10 ppm GNPs also enhanced seedling vigor index by 3 times over the control. Priming with GNPs at 10 ppm was found to enhance the best physiological and biochem- ical properties of maize seedlings. Internalization studies by inductively coupled plasma atomic emission spec- troscopy (ICP-OES) and transmission electron microscopy (TEM) strongly supported that GNPs can internalize into seeds. However, ICP-OES analysis revealed that GNPs were not present in both shoot and root parts, suggest- ing that nanopriming approach minimizes the Au translocation from seeds into plant vegetative organs. Phytosynthesized GNPs were found to be less toxic than chemically synthesized GNPs. This is the first report Keywords: Gold nanoparticles Green nanotechnology Nanopriming Aged seeds Maize Science of the Total Environment 573 (2016) 1089–1102 ⁎ Corresponding authors. E-mail addresses: piythe@kku.ac.th (P. Theerakulpisut), a.sarmah@auckland.ac.nz (A.K. Sarmah). http://dx.doi.org/10.1016/j.scitotenv.2016.08.120 0048-9697/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv