Root system distribution and density of 'Pinot Gris': effect on yield and grape quality

The response of the grapevine to different soil characteristics utilises the root system as its interface. Soil depth, layering, and texture are important sources of variability in grapevine production, due to their effects on soil water availability and vine root distribution. To better understand the plant-soil interaction, the root system was studied in four different soils, using the trench method. Since the weather characteristics were similar between the studied vineyards, the soil played a major role in vine condition and affected yield, vine growth and grape composition. In soils with high clay content, the roots were mainly concentrated in the upper soil layers. This led to strong yield variation between dry and wet seasons. Conversely, in soils with less clay content, the root system was homogeneously distributed all along the soil profile, and this sustained a constant yield despite low root density. In clay loam soils, the root system was mainly located between 20 and 80 cm in depth, with almost 90% of the roots located at these depths. When a mechanical barrier (i.e., rock) was present, it seemed to be the cause of a reduced root density. The study confirmed the great importance of root system analysis in order to better understand vine performance and soil water use by the vine through the roots. Moreover, yield consistency seemed correlated with root system distribution, a superficial root system leading to larger yield fluctuations between seasons.