Foliar Nutrition Influences Yield, Nut Quality and Kernel Composition in Hazelnut cv Mortarella

In hazelnut, foliar nutrition is utilized globally to integrate microelement deficiencies and optimize their assimilation and effects on yield performances. Nevertheless, nut quality and kernel composition can be positively affected by foliar nutrition. Recently, several studies pointed out the need for increasing the sustainability of orchard nutrition by proposing the management of not only micronutrients, but also main components, such as nitrogen, through foliar spraying. In our study, different foliar fertilizers were used to understand the effectiveness of supporting hazelnut productivity and nut and kernel quality. Water was used as a control. Foliar fertilizations affected tree annual vegetative growth, improved kernel weight and decreased the incidence of blanks compared to the control. Differences in fat, protein, and carbohydrate concentration were also found among treatments, with increased fat concentrations and total polyphenols content in fertilized treatments. Foliar fertilization improved the oil composition of the kernels, though 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 spraying improved lipid stability compared to the control due to higher total polyphenol concentration.

Automated summary

Foliar nutrition is used globally to address microelement deficiencies and optimize yield performances, but it can also positively impact hazelnut nut quality and kernel composition. Recent studies emphasize the importance of managing not only micronutrients, but also major components like nitrogen for sustainable orchard nutrition. In our research, various foliar fertilizers were tested to understand their effectiveness in supporting hazelnut productivity and improving nut and kernel quality. The results showed that foliar fertilization influenced tree growth, increased kernel weight, and reduced blank incidence compared to the control. Treatment differences were also observed in fat, protein, and carbohydrate concentration, with fertilized treatments showing higher fat concentrations and total polyphenol content. The composition of oil in the kernels was also improved through foliar fertilization, although the response of fatty acid composition to nutrient spray varied. Oleic acid concentration increased while palmitic acid concentration decreased in fertilized plants. Additionally, CD and B trees exhibited a higher ratio of unsaturated/saturated fatty acids compared to untreated trees. Finally, foliar spraying improved lipid stability by increasing total polyphenol concentration.