Observatoire du Grenache en Vallée du Rhône: incidence du terroir sur la diversité analytique et sensorielle des vins

This experiment tries to characterize the role of soil, climate and harvest date on the composition of grape-derivated thiols, 3-mercapto-hexanol (3MH) and 3-mercapto-hexile acetate (A3MH), in the white wines from Colombard varieties in Gascony (South-West of France). A network of 6 plots has been observed since 1999 on different pedologic units. The plots have common agronomical characteristics, plantation spacing (2,900 to 3,500 vines per ha), plantation aging (1985-1990), strength conferred by rootstock (SO4, RSB), soil management (grass covered 1 by 2) and training system (vertical shoot positionning pruned in single Guyot). Meteorological stations are located near the plots.

Farming management practices aiming at conserving soil moisture have been developed in arid and semiarid-areas facing water scarcity problems. Organic mulching is an effective method to manipulate the crop-growing microclimate increasing crop yield by controlling soil temperature, and retaining soil moisture by reducing soil evaporation. In this sense, the effectiveness of different organic mulching materials (straw mulch and grapevine pruning debris) applied within the row of a vineyard was evaluated on the soil and on the vine in a Tempranillo vineyard located in La Rioja (Spain). Organic mulches were compared with a traditional bare soil management technique (based on the use of herbicides to avoid weed incidence). Mulching coverages favourably influenced the soil water retention throughout all the grapevine vegetative cycle. However, the soil-moisture variation was not the same under different mulching materials, being the straw mulch (SM) the one that retained more water in comparison with grapevine pruning debris (GPD) based-cover. The changes of soil moisture in the upper surface layer (0–10 cm) were highly dynamic, probably due to water vapour fluxes across the soil-atmospheric interface. However, both, SM and GPD reduced these fluctuations as compared with bare soils. A similar trend occurred with soil temperature. Both organic mulches altered soil temperature in comparison with bare soil by reducing soil temperature in summer and raising it in winter. Moreover, the same buffering effect for the temperature on the covered soil also remains in the deeper layers. To conclude, we could see that organic mulching had a positive impact on soil-moisture storage and soil temperature and the extent of this effect depends on the type of mulching materials. These changes led to higher rates of photosynthesis and stomatal conductivity compared to bare soils, also favouring crop growth and grape yields.

Considérant d’une part la judicieuse mise au point d’un label de qualité contrôlée des miels suisses (STÖCKLI et al. 1997), considérant d’autre part l’élaboration d’une carte des paysages végétaux (HEGG et al. 1993),

In the current climatic context, with milder winters leading to earlier budburst in most wine regions, vines are exposed to the risk of spring frosts for a longer period. Depending on the year, frost can lead to yield losses of between 20 and 100 %, jeopardizing the economic survival of wine estates. In addition, by destroying young shoots, spring frosts can impact the following season’s production, by reducing the number of canes available for pruning, for example. Late pruning is one method to combat spring frosts.

Stomata are microscopic pores mainly located in leaf epidermis, allowing gas exchanges between plants and atmosphere. Stomatal initiation relies on the transcription factor SPEECHLESS which is mainly regulated by the MAP kinase cascade, in turn controlled by small signaling peptides, the Epidermal Patterning Factors (EPF and EPF-Like), namely EPF1, EPF2 and EPFL9. While EPF1 and EPF2 induce the inhibition of SPEECHLESS, their antagonist, EPFL9, stabilizes it, leading to stomatal formation. In grapevine, there are two paralogs for EPFL9, VviEPFL9-1 and VviEPFL9-2. Despite their structural similarity, it remains unclear whether they are differentially regulated and have distinct roles.