Foliar Nutrition Improves Kernel Composition And Quality In Hazelnut

In hazelnut foliar nutrition has been worldwide utilized to integrate microelements deficiencies and to optimize their assimilation and effects on yield performances. Nevertheless, nut quality, and kernel composition can be positively affected by foliar nutrition. Several studies have pointed out the need for an increasing sustainability of orchard nutrition, by proposing to manage not only micronutrients but also main components such as nitrogen through foliar spraying recently, but the influence on kernel composition and quality has been less investigated. In our study, a foliar fertilizer (CD), containing nitrogen and microelements (B, Zn and Fe) was compared to boron ethanolamine (B), to understand the effectiveness of supporting hazelnut productivity and nut and kernel quality of a cv Mortarella orchard, in a three year trial. Water was used as control. Foliar fertilizations affected tree annual vegetative growth, improved kernel weight and decreased the incidence of blanks compared to control. Differences in fat, protein, and carbohydrate concentration were also found among treatments, with an increased fat concentration and total polyphenols content in fertilized treatments. Foliar fertilization improved oil composition of the kernels, but fatty acid composition responded differently to nutrients spray. Oleic acid concentration was promoted while palmitic acid concentration was reduced in fertilized plants compared to control trees. Furthermore, CD and B trees were characterized by an increase in the ratio of unsaturated/saturated fatty acids compared to untreated trees. Finally, foliar spray improved lipid stability compared to control, due to higher total polyphenol concentration.