Impact of grapevine age on water status and productivity of Vitis vinifera L. cv. Riesling
Résumé
Grapevines are perennial plants that can display remarkable longevity. It is often thought that some of their characteristics evolve in a positive way as they grow older, such as having a higher tolerance to water deficit and an improved balance between vegetative and reproductive growth. However, only a few studies have been conducted so far on the possible effects of age on vine productivity and water status.
An experimental vineyard was designed in the German Rheingau region to compare vines of identical planting material planted at three different times. The vineyard was established in 1971 with Vitis vinifera (L.) cv. Riesling vines (clone Gm 239-17) grafted on 5C Teleki and trained in double Guyot and cordon in alternating rows. In 1995 and 2012, rows of both training systems were uprooted and replanted with the same scion/rootstock combination. The aim of this study was to evaluate the impact of vine age on several physiological and reproductive parameters. Vines planted in 2012 were generally more sensitive to water deficit than vines planted in 1995 and 1971, although this depended on the amount of precipitations during the growing season. A supporting trial was carried to create more intense drought conditions by deploying a plastic mulch around selected vines during rain events. Young vines were most affected by the treatment, suggesting that their lower trolerance to water deficit might be due to a shallower root system. Vines planted in 1995 and 1971 displayed similar response to water deficit. Canopy architecture, cluster parameters and vine balance components including pruning weight and yield were different for the youngest vines until the fifth year after planting due to their lower cropping capacity. Even though the observed yield and pruning weight per meter were lower for grapevines planted in 1971 than those planted in 1995, these variables were similar across the two age groups when missing vines were taken into account. Wood diseases were identified as the main factor behind the decline of old vines. The study suggests that the management of wood diseases is a key component in improving vineyard longevity, and that the conservation of grape yield and technological maturity parameters for vineyards in similar environmental conditions is indeed possible over the long term.