Relationships among plant traits, soil characteristics and olive oil properties in different Olea europaea L. cultivars

Extra virgin olive oil (EVOO) is a typical product of the Mediterranean region. The knowledge of the relationship between plants and the soil type allows to improve the choice of crops that better satisfy the human need. The composition of EVOO may be influenced by both plant physiological characteristics (i.e cultivar, stage of maturity and integrity of the fruit, and the oil production technology) as well as soil specific physical, chemical and biological properties. The aim of this work was to assess the relationships between soil properties, functional leaf traits, fruits and oil quality in different Italian Olea europaea L. cultivars (Pisciottana, Ravece, Ortice, Frantoio and Moraiolo). Soil analyses indicated Ravece as the cultivar with the highest cationic exchange capacity and water holding capacity. Soil under Pisciottana showed the highest organic matter content differently from of soil covered by Ortice cultivar. These soil characteristics seem to affect functional leaf traits. In particular, Pisciottana and Frantoio trees showed similar SLA values higher than other cultivars but a different pattern of C/N: the highest and the lowest values respectively. As regard olive oil properties Pisciottana showed a reduced amount of total polyphenols (TPC) and the strongest antioxidant activity. On the contrary Moraiolo oil was characterized by higher levels of TCP and lower free acidity and peroxide content than the other cultivars. Similar properties were observed in Ortice oil. Data showed that soil, leaf characteristics and oil quality are closely related: a slower organic matter turnover determines more allocation of carbon in plant mechanical tissues favouring the production of an oil rich in antioxidant compounds in Pisciottana. On the otherwise a soil less abundant in nutrients, such as Frantoio and Moraiolo, seems to induce the production of low-quality standard oil.