Onion Biofortification Using Selenium Bionanofertilizer and its Bulk Source under Sandy Soil Conditions

Human health depends on the daily supply of fresh vegetables and fruits, which contain the essential, nutrients, vitamins and other bioactive compounds. Due to malnutrition in several places all over the world, the biofortification approach is a crucial solution to overcome this global problem. In the current study, the biological nanofertilizer of selenium (nano-Se) was tested on onion crop comparing with its bulk source under the sandy soil conditions. the applied doses of nano-Se were 10, 20, 30 and 40 mg L⁻¹ in both nano and mineral form of Se. The main investigated parameters of onion were the vegetative growth parameters and the nutritional status in leaves and bulbs. The obtained results have a significant difference between mineral and nano-Se doses for studied measurements. In general, all studied parameters increased in their values with increasing the applied doses from both Se sources up to 30 or 40 mg L⁻¹ compared to the control, depending on the selected parameter. This increase reached to more than 60% (for applied nano-Se on bulb dry weight), or more than 55% for the same parameter after applying mineral Se source. Applying nano Se was achieved higher values in some studied parameters of onion, whereas the mineral form of Se was domain for others. This study confirmed that both Se forms can be applied for biofortification of onion because the Se content in bulb located in the accepted level of Se in crop with priority to nano-Se, which accumulate in leaves and bulb in a lower concentration compared to mineral form. This work opened more question about the nano-biofortification and the possibility to apply for more studied crops with focus on the suitable added dose to be safe for successful biofortification program.