Elham Yusefi-Tanha - Department of Agronomy, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran.
Sina Fallah - Department of Agronomy, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran.
Ali Rostamnejadi - Department of Electroceramics and Electrical Engineering, Malek Ashtar University of Technology, Iran.
Lok Raj Pokhrel - Department of Public Health, The Brody School of Medicine, Department of Health Education and Promotion,College of Health and Human Performance, East Carolina University, Greenville, NC, USA.

Zinc is an essential micronutrient that plays a key role in a numerous of physiological processes of plants, thus bioenrichment of zinc can be effective to improve plant growth and seed quality. In this study, we synthesize three sizes of zinc oxide nanoparticles (۳۸, ۵۹, and >۵۰۰ nm) with high purity, and assessed the potential influence of particle size and concentration (۰, ۵۰, ۱۰۰, ۲۰۰, and ۵۰۰ mg/kg soil) of ZnONPs on seed oil and protein content, and seed N, P, K, and Zn concentration during the whole growth period of soybean plant (۱۲۰ days), and compared them with the soluble Zn۲+ ions and water-only controls. We observed particle size- and concentration-dependent influence of ZnONPs on oil and protein content, and N, P, K, and Zn concentration in soybean seeds. Overall, soybean responses to the smallest size of ZnONP-۳۸ nm were greater for all parameters tested compared to the two larger-sized ZnONPs (ZnONP-۵۹, ZnONP >۵۰۰) and Zn۲+ ions treatments up to ۲۰۰ mg/kg. Whereas with increasing concentration (۵۰۰ mg/kg), all traits tested showed a decreasing trend compared to the control, except the amount of seed Zn. Seed TEM images also showed the size of protein storage vacuoles and oil bodies in the seed embryo of plants treated with ۵۰۰ mg/kg of ZnONP-۳۸ nm decreased compared to the control. Improving nutrients, oil and protein amount in soybean seeds up to ۲۰۰ mg/kg indicates the potential for using ZnONPs fertilizer for plants grown in zinc-deficient soils to improve seed quality.

Bioenrichment, Essential nutrients, Nanoparticles, Seed