Conséquences de la saison 2021 sur le rendement quantitatif en viticulture wallonne

peer reviewedPassant de 150 ha (pour 36 exploitations) en 2018 à 300 ha (pour 64 exploitations) à la fin de 2021, la surface viticole wallonne (Belgique – figure 1.a) n’a cessé de croître ces dernières années. Cependant, en 2021, les vignobles wallons ont été fortement touchés par le mildiou (Plasmopara viticola) dû à des conditions météorologiques exceptionnellement humides et fraîches. Cette étude montre que les pertes quantitatives ont été hétérogènes entre les vignobles. Cette variabilité est expliquée principalement par le type de cépage, le mode de production et la gestion liée aux maladies

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Du stress hydrique dans les vignobles belges ?

Cas d’étude du Vignoble du Château de Bousval et du Domaine W lors de la sécheresse exceptionnelle de l’été 202

Argenteuil (Val-d'Oise). Carême-Prenant

Bernard Jean-Louis, Delval Marc. Argenteuil (Val-d'Oise). Carême-Prenant. In: Archéologie médiévale, tome 27, 1997. p. 140

Belowground hydraulic resistance generates stomatal closure of grapevine in soil water-limited conditions

Climate change will exacerbate drought events in many regions, increasing the demand on freshwater resources and creating major challenges for viticulture. In viticulture, the terroir governs the hydraulic behavior of the vine. The terroir is defined as the interactions between climate, soil, plant material (vine and rootstock varieties) and human management practices. The knowledge on grapevine drought stress physiology has increased significantly in recent years, but a holistic comprehension on how soil-plant hydraulic resistances develop and are regulated remains poorly understood. In particular, how different soil-rootstock combinations and their plasticity affect the vine hydraulic condition is still an open question. The objective of this study is to understand the hydraulics of the soil-plant system in grapevines (Vitis vinifera cv. Chardonnay) in situ, for different soil-rootstock combinations in a temperate oceanic climate, and to investigate its influence on vine water status. The concomitant and automatic monitoring of soil and collar water potentials, as well as sap flow, made it possible to characterize the evolution of the soil-vine hydraulics in situ in real-time, with hourly measurements for two months. In order to investigate the impact of the soil-rootstock combination, two Belgian vineyards with the same variety (cv. Chardonnay) were selected due to their intra-field heterogeneity of soil physico-chemical properties (two study areas per vineyard). The vines of the first vineyard are grafted on the rootstock 3309C and planted on sandy or loamy soils. Those of the second vineyard are associated to the rootstock 101-14Mgt and grow on loamy or silty-clay soils. In each vineyard the soil is therefore the only variable factor, for which hydraulic properties were measured to a depth of 2 m. The measurements were collected between mid-July and mid-September, during a period of exceptional drought in Belgium leading to soil water-limited conditions (rainfall anomaly of -153,8 mm and -148,4 mm in the first and second vineyard respectively over this period). The mean soil-plant conductances observed over the season were respectively 0,54.10-5 cm.s-1.MPa-1 and 2,18.10-5 cm.s-1.MPa-1 in the sandy and loamy areas of the first vineyard, and 1,79.10-5 cm.s-1.MPa-1 and 2,97.10-5 cm.s-1.MPa-1 in the silty-clay and loamy areas of the second vineyard. Despite this extreme drought, the minimum observed stem water potential (Ψstem) was -1,47 MPa (sandy study area of the first vineyard). This is in line with other studies that have shown in situ vines typically work within a safe range of water potentials (Ψstem > -1,5 MPa) that do not lead to cavitation or turgor loss. These first observations validate the hypothesis that the increase of belowground hydraulic resistance triggers stomatal closure of vine

Consequences of the 2021 season on yields from vineyards in Wallonia

Weather conditions in Wallonia were exceptionally wet and cool in 2021 The weather conditions in Wallonia in 2018, 2019 and 2020 favored high yields, rising to more than 10,000 hl (45 hl.ha-1) in 2020. According to the Huglin index1 (HI), the 2018 growing season was temperate (1800 < HI < 2100) over most of Wallonia, while the 2019 and 2020 seasons were rather cool (1500 < HI < 1800) (Figure 1.b). These same three years saw a negative rainfall anomaly (ΔP = P - Pnormal) compared with the norm for the whole region, reaching a cumulative deficit of -300 mm between 1 April and 30 September. The 2021 growing season was very cool (HI ≤ 1500) everywhere in Wallonia and exceptionally wet, with a positive ΔP of up to +300 mm (Figure 1.c). As in vineyards in the south of France in 2018, long rainfall sequences allowed the spread of downy mildew. Between 1 April and 30 September 2021 (183 days), it rained on between 70 and 106 days (Figure 1.d), with an average of 3 to 6 consecutive days of precipitation for each rainfall event (Figure 1.e)

Quantification of intrafield variability of vine water status using Sentinel 2: case study of two Belgian vineyards

For decades, vines have been grown in dry regions, as the plant has to grow under water deficit to produce quality wines. Due in part to climate change, vine cultivation is developing in historically cooler and more humid regions. In addition to climate, soil and plant material are the terroir factors that most influence the water status of the vine, and conditions can be different within the same vineyard plot, implying heterogeneous vineyard management to achieve optimal wine quality. The objective of this study is to explore the potential of Sentinel-2 to characterize the intra-plot variability of vine water status and its evolution through time. Two Belgian vineyards, with high soil water availability intra-plot variation and different grape varieties, were selected. Both vineyards have grass in the inter-row and the spatial distributions of soil depth and soil water holding capacity (WHC) were measured. A cumulative drought index (DIcum) was also estimated for each plot. Four years (2018, 2019, 2020 and 2021) of Sentinel-2 images of these two Belgian vineyards were analyzed. Several spectral indices, based on the blue, red, NIR and SWIR bands on a 10 x 10 m² grid, were calculated and compared to quantify the evolution of the water status of the vine, as a function of the weather conditions (DIcum), the grape variety and the WHC. Predawn leaf water potential (Ψpd) measurements were collected in situ at different dates during dry periods in order to compare them with the remote sensing indices. We observed that spectral indices and the WHC were better correlated when the water conditions were the most constraining for the vine (e.g. R² = 0.72 on 16/08/18 for NDWI/EVI), i.e. when DIcum is lowest. Edaphic heterogeneity is therefore better captured by spectral indices when conditions are dry for the vine. The spectral indices have a low value when the WHC is low, and vice versa. The spectral index NDWI/EVI quantifies the water status of the vine better than the NDWI, when comparing linear regressions between the two spectral indices and the Ψpd measured in the field (R² = 0.67 for NDWI/EVI; R² = 0.64 for NDWI). In conclusion, the NDWI/EVI spectral index, measured from the Sentinel-2 bands, is promising for quantifying the spatial distribution of vine water status on a regular basis at the plot scale

L’acquisition à haute densité et la modélisation 3d : Lidar, photogrammétrie et Building Information Model, comme nouveaux champs exploratoires.

International audienc

Hydraulics of the soil-vine system in Walloon terroirs and influence on berry quality

Grapevine (Vitis vinifera) is one of the most economically important fruit crops worldwide and is cultivated in more than 90 countries nowadays. In ten years, the Belgian wine-growing area has more than quadrupled and this continues to increase. A reason is that drought events will be more frequent in Belgium, resulting from climate change. Grapevine has emerged as a model perennial fruit crop for the study of drought effects, as it affects hydraulics of the plant and fruit composition. There are numerous hydraulic traits that determine a vine’s response to water availability: stomatal regulation, root characteristics, xylem architecture, aquaporin regulation, ABA dynamics and osmotic adjustment. All these traits can also be influenced by the grape variety, the rootstock, the soil, other environmental variables such as VPD and light, and their interactions, which also play important roles in the composition and quality of grapes. How different couples variety-rootstock respond to drought, in terms of hydraulics and fruit quality, remains an open and critical question. It is also unclear to what extent regulations of vine hydraulics result from innate genotypic traits or environmental factors. Numerous gaps remain in our understanding of the vine’s behavior in oceanic temperate climate and how climate change could affect Belgian viticulture

Soil hydraulic conductivity defines minimum Root:Shoot surface ratio in moisture-limited environments

In drying soils, root water uptake is limited by the low soil hydraulic conductance. The magnitude of this conductance drop and its temporal dynamics are function of soil texture, soil water status, root hydraulic architecture, atmospheric demand and canopy conductance. Under dry climates, in order to survive, plants can adapt their carbon allocation by maximizing their root:shoot surface ratio, thereby decreasing their transpiration surface while increasing their root surface. Thanks to a simple soil-plant hydraulic model, we show that soil hydraulic conductivity controls the minimum root:shoot surface ratio. A meta-analysis of shoot:root surface ratio is combined with a database of soil hydraulic properties to demonstrate how the minimum root:shoot surface value changes with soil conductivity across soil textural classes for dry biomes. We discuss the mechanisms by which plants can control their carbon allocation in such conditions and investigate the sensitivity of this minimum root:shoot surface ratio to future shifts in evaporative demand