Effects of Edaphic Fertilization and Foliar Application of Se and Zn Nanoparticles on Yield and Bioactive Compounds in Malus domestica L.

In this study, we evaluated the effects of edaphic fertilization with N, P, and K (150-50-80, 100-60-60, and without edaphic fertilization (SFE)) and foliar fertilization with nanoparticles (NPs) of Se and Zn (Se: 50 ppm, Zn: 250 ppm, and no nanoparticles (NPO)) on the yield and antioxidant compounds of apple fruits. We conducted this study in a 20-year-old commercial orchard. The experimental design was a randomized complete block design of nine treatments. The treatments with fertilization doses of 150-50-80 and 100-60-60, supplemented with Se and Zn NPs, generally increased the yield, sugar content, and ascorbic acid of the apple fruits. The SFE + NPZn treatment produced the highest increase (+193% compared with the control) in fruit yield. The SFE + NPSe and SFE + NPZn treatments led to higher contents of phenols and flavonoids, with maximum values of 7.6 mg GAE and 15.82 mg QE per gram of dry weight. These compounds presented a direct correlation with the antioxidant activity in the fruits. The foliar application of Se and Zn nanoparticles supplemented the soil fertilization with N, P, and K to improve the yield and bioactive-compound synthesis of the apple fruits.