RELATIONSHIPS BETWEEN SOIL CHARACTERISTICS AND LEAF NUTRIENT CONCENTRATIONS IN GRAPEVINE

Abstract

The results of a study investigating the relationships between different soil chemical-physical characteristics and nutrient concentrations in leaf tissues of grapevine (Vitis vinifera L.) are reported. The main feature of the experimental site, its high soil spatial variability, allowed examination of the variables of interest while keeping constant crop variety, plant age, climatic conditions and agronomic techniques management, the variability of which is often cause of data misinterpretation. The research was carried out on a winegrape vineyard, cv. Trebbiano Toscano grafted on 1103P rootstock, in Southern Italy. Ten areas characterised by different soil average fertility were selected within the experimental field and, within each area, two representative plants were chosen as test plants. Soil samples at three depths and leaf blades at three sampling times (end of bloom, fruit set and veraison) were collected. In the soil, total N content was positively correlated with organic C, available P and exchangeable K and inversely related to total CaC0 3 content. Among the leaf mineral nutrients, P showed the highest variation in relation to soil parameters (positive correlation with N content, organic C, available P; negative with CaC0 3 ) at the end of bloom and at veraison. Total leaf N was positively correlated with soil organic C and available P only at veraison. Moreover, in this stage, a higher Ca and Mg leaf content was observed in the areas characterised by a lower chemical fertility (lower total N and organic C; higher CaCO 3 ). Principal component analysis clearly discriminated areas of different soil fertility and underlined the variation in tissue nutrient concentrations as a function of soil chemical and physical properties.