Influence of Soil on Root Distribution: Implications for Quality of Tocai Friulano Berries and Wine

Abstract

The Tocai Friulano cultivar grafted onto SO4 rootstock was studied for three years in four soil types (SU1 to SU4) in the Colli Orientali del Friuli AOC, Italy. The grapevine root system, soil chemical and physical properties, soil water regime, vine performance, and grape and wine quality were studied with the aim of better understanding how roots mediate the vine response to different soil characteristics. Climate was homogeneous in the study area, and the effect of weather was evaluated on an annual basis. Our results showed that soil played a major role in water availability to the vine and affected vine yield components, vegetative growth, vine balance, grape composition, and wine sensory profile. Observation of roots provided information about variability in vine performance and wine characteristics. Good, stable wine quality was obtained only in soils that allowed development of a deep root system (SU1 and SU4); these soils produced satisfactory wine quality even in dry seasons. In dry years, an imbalance between vegetative and reproductive growth occurred in shallow soils, in which the root systems were thin and superficial (SU2), and led to poor-quality grapes and wines. Conversely, the wines showed more interesting characteristics when the root systems were more dense and distributed throughout the soil profile (SU3). These results underline the importance of analyzing root characteristics when evaluating the vine response to the soil–climate environment.