Rootstocks compared: a three-year study of Chardonnay in Franciacorta - Northern Italy district

The rootstock turns out to be crucial to ensure good adaptation of the vine to local soil and climatic conditions.

A three-year evaluation of 8 Chardonnay grafts (SO4, 1103P, 110R, 420A, M1-4) grown in the same vineyard in Franciacorta was prepared.

The results of 2021 and 2022, vintages with significant water stress, showed that at the same soil water potential, the combinations have different behaviors, showing more or less conservative responses depending on the genotype. It is interesting to note the different response of the combinations to the continuation of moderately stressful conditions. In fact, some rootstocks, such as M4 or M3 tend to increase transpiration while others close their stomata and thus decrease it such as 420A and 110R.

In 2022, under moderately stressed conditions, M4 and M1 showed higher water-use efficiency, while 1103 and SO4 higher photosynthetic activity. Interestingly, by moving to a highly stressful condition, the drop in photosynthetic activity is smaller in M1 and M4 than in 1103 and SO4. M4, moreover, shows significantly higher water use efficiency. M-series rootstocks showed comparable performance to traditional genotypes, both in terms of production and grape quality characteristics. They tend to be less vigorous and somewhat less productive, but potentially more qualitative since they have smaller berries and clusters.