Precision nano-fertilization as a strategy to enhance growth and sweetener accumulation in stevia under arid sandy soil conditions

The escalating demand for natural, low-calorie sweeteners has elevated Stevia rebaudiana as a strategic crop of economic and nutritional importance. Optimizing agronomic practices, particularly fertilization strategies, is crucial for enhancing both biomass and steviol glycoside content. This two-season field study aimed to assess the effects of nano-fertilizer applications, including nano-NPK, nano-ZnO, and nano-Fe₂O₃, on the growth, nutrient uptake, and sweetener profile of Stevia cultivated in the sandy soils of Giza, Egypt. Results revealed that the integrated nano-fertilizer treatment (T5: nano-NPK + ZnO + Fe₂O₃) significantly improved plant height, biomass accumulation, nutrient assimilation, and concentrations of stevioside and rebaudioside A compared to conventional fertilization. These enhancements are attributed to the superior solubility, controlled release, and higher bioavailability of nano-formulations, which enhanced nutrient use efficiency under the leaching-prone, low-retentive conditions of sandy soils. This study affirms the agronomic potential of nano-fertilizers in sustainable, high-value crop production systems.