Proposition of a simplified approach of the viticultural landscape

The study of the physiological behaviour of the grapevine (cv. Chasselas), and of plant hydraulics in particular, was conducted on various « terroirs » in the Canton of Vaud (Switzerland) between 2001 and 2003 by Agroscope Changins-Wädenswil ACW, in collaboration with the firm I. Letessier (SIGALES) in Grenoble and the Federal Polytechnic School of Lausanne (EPFL). An evaluation of the vine plant hydraulics was made by means of physiological indicators (leaf and stem water potentials, transpiration and leaf stomatal conductance, carbon isotope discrimination and a model of transpirable soil water), in relation to estimations of the soil water reservoir and climatic factors.

Elevated temperature during the grape maturation period is a major threat for grape quality and thus wine quality. Therefore, characterizing the grape composition response to temperature at a larger scale would represent a crucial step towards adaptation to climate change. In response to changes in temperature, various physiological mechanisms regulate grape composition. Primary and secondary metabolisms are both involved in this response, with well-known effects, for example on anthocyanins, and lesser known effects, for example on aromas or aroma precursors. At the field scale or at the regional scale, however, numerous environmental or plant-specific factors intervene to make the effects of temperature difficult to distinguish from overall variability. In this study, it was attempted to overcome this difficulty by selecting well-characterized situations with differing temperatures.
A long-term study of air temperature variability across several Merlot vineyards in the Saint-Emilion and Pomerol wine producing area found significant temperature differences and gradients at various time scales linked to environmental factors. From this study area, a few sites were selected with similar age, soil and training system conditions, and with repeated and contrasted temperature differences during the maturation period. The average temperature difference during the maturation period was about 2°C between cooler and warmer sites, a difference similar to that expected under future climate change scenarios. In close vicinity to the temperature sensors at each site, grape berries were sampled at different times until full maturity during 2019 and 2020. Also, berries from bunches on either side of the row were analyzed separately, allowing an investigation of bunch exposure effect associated with the coupling of berry temperature and solar radiation. Four replicates of pooled berries for each time – site – bunch exposure combination were obtained and analyzed for biochemical composition. Analyses of variance of the biochemical composition data collected at different sampling times reveal significant effects associated with temperature, site, and bunch azimuth. For instance, anthocyanins in grape skins are clearly influenced by temperature and solar radiation exposure, with up to 30% reduction in warmer conditions.

Changes in the rainfall and temperature patterns affect the increase of drought periods becoming one of the major constraints to assure agricultural and crop resilience in the Mediterranean regions. Beside the adaptation of agricultural practices, also the microbial compartment associated to plants should be considered in the crop management. It is known that the microbial community change according to several factors such as soil composition, agricultural management system, plant variety and rootstock.

The elemental composition (the ionome) of grape leaves is an important indicator of nutritional
health, but its genetic architecture has received limited scientific attention. In this study, we
analyzed the leaf ionome of 131 interspecific F1 hybrid progeny from a Vitis rupestris (♀) X Vitis
riparia (♂) cross. The progeny were replicated in New York, South Dakota, Southwest Missouri ad Central Missouri, and the concentration of 20 elements were measured in their leaves at
three different phenological stages during the growing season. In leaves collected at the apical node at anthesis, elemental concentrations correlated in a consistent manner (p < 0.05) across all four geographic locations. In subsequent phenological stages, elemental ratios in the apical-node leaves remained consistent across the South Dakota and New York sites, but not across the Missouri sites. In leaves collected at the basal and middle nodes, correlations varied greatly across all locations.

Grapevine is one of the most-frequently phytosanitary treated crop systems. Consequently, restrictions have been applied by the European Commission on the number of pesticide treatments and the maximum quantity of copper fungicides allowed per year. Moreover, there is a need and an increasing demand for more ecological-sustainable agricultural products.
Seaweeds are currently used as fertilizers in viticulture, as they have been proven to be beneficial in several ways related to growth and nutrition.