New Syrah Clones Selected at Agroscope

A survey conducted in a Syrah population originating in Northern Côtes du Rhône (France) resulted in the selection of three new Syrah clones with highly promising characteristics, distributed by the Swiss certification sector.

The breeding of Syrah in Switzerland

Introduced in Switzerland in 1926, the internationally widespread grape variety Syrah is now cultivated on a surface area of nearly 200 ha, occupying sixth place for red grape varieties, En 2012, a survey conducted in a Valais vineyard involving a clone population originating in Northern Côtes du Rhône (France), specifically, from the prestigious ‘Côte Rôtie’ AOC, led to the selection of fourteen clone candidates. From 2018 to 2021, their agronomic and oenological performances were compared to those of the Agroscope RAC 78 clone and the French ENTAV 470 clone in a study conducted on Agroscope’s experimental farm in Leytron (Canton of Valais).

Promising intra-varietal variability

Observations have led to the identification of a fairly significant clonal diversity for the majority of the agronomic aspects, in particular for production potential, bunch morphology and must composition. The trial has resulted in the proposal of three new Syrah clones (RAC 97, RAC 98, RAC 99), all of which exhibit a high qualitative potential in terms of the wines and which are characterised by strongly differentiated profiles as regards their agronomic suitability.

Aromatic marker

The typical peppery character of Syrah wines stems from their rotundone content – a molecule from the sesquiterpene family. Analysis of the rotundone content of the wines revealed that it is not an effect associated with the clone but rather the water regime of the vine during ripening that is largely responsible for the levels of this aromatic compound.

Syrah dieback

Syrah vines are subject to a specific dieback phenomenon leading to the death of the affected vines in several years. Both physiological and genetic factors seem to play a key role in this context. Researchers from the French Institute of Vine and Wine (IFV) identified three genetic markers allowing classification of the Syrah clones on the basis of their susceptibility to this phenomenon. Analysis of these microsatellite markers revealed that all the Syrah clones approved by Agroscope (RAC 78, RAC 97, RAC 98, RAC 99) belong to the group containing clones with a very low susceptibility to dieback.