The Relationship Between Terroir and The Phenology of Barossa Shiraz

Abstract

Background and Aims: Vine phenology results from the interaction between the genotype, environment and management, with implications for fruit, and wine composition. The impact of weather, site and management practices, underlying elements of terroir, impacting the timing of key phenological stages were explored across the Barossa Zone (GI). Methods and Results: Vine phenology was assessed in three zones of 24 vineyards over three vintages using the E-L scale before veraison, and total soluble sugars (TSS) in berries during ripening. We explored the associations between weather, plant traits and viticultural variables, and development in four periods: pre-budburst, budburst-flowering, flowering-veraison and veraison-maturity. The spatial structure of the timing of phenological events suggested three main groups of vineyards. This structure followed gradients in topography and soils across the landscape, and were maintained despite the effect of the season (vintage). On average, differences between early and late groups of vineyards were 13 days at budburst, 20 days at flowering and 24 days at TSS = 24 oBrix. Phenology responded mainly to temperature until flowering, and to temperature and canopy size from flowering to maturity. The strength of the relationship between the duration of the period and temperature ranked pre-budburst (r2 = 0.94) > budburst-flowering (r2 = 0.40) > veraison-maturity (r2 = 0.17). Duration of pre-budburst and budburst-flowering periods was shortened at 6 d oC-1, compared to 2 d oC-1 for veraison-maturity. The duration from veraison to maturity increased with yield (r2 = 0.29, Pa < 0.0001). Conclusions The spatial variation in development was maintained despite vintage effects and management practices. Variation in temperature due to topography and elevation were the major drivers of vine phenological development until flowering. During ripening, development was driven by temperature and carbon capture and partitioning. Significance of the Study This is the first attempt to show spatial variability on phenology across the Barossa Valley GI. The observed switch on drivers on phenology during development from temperature-driven processed before flowering to resource-dominated processes during ripening have implications for modelling and vineyard management.

Benchmarking water-limited yield potential and yield gaps of Shiraz in the Barossa and Eden Valleys

“…Data were logged every 15 minutes and retrieved from the logger at least monthly for processing using the IrriMax10 software (Sentek, Magill, South Australia). Details of probe calibration and calculations of plant available water are in Bonada et al (2022). Crop evapotranspiration (ETc) and its components (transpiration, Tp; and evaporation, Es) were estimated using the FAO-56 dual-crop coefficient approach (Allen, et al 1998) as described in Phogat et al (2020).…”

“…Weather, soil moisture and water balance Bonada et al (2022) describe the measurements of weather and components of the soil water balance in detail. Briefly, 24 weather stations (MEA Junior WS, Magill, South Australia), one at each site, were installed at the beginning of the experiment to log temperature, relative humidity, wind speed and direction, solar radiation, and rainfall at 15-minutes intervals; daily reference evapotranspiration (ETo) was calculated with the method of Penman-Monteith {Allen, 1998 #4188}.…”

“…The subregions are Northern Grounds (NG), Central Grounds (CG), Eastern Edge (EE), Southern Grounds (SG), Western Ridge (WR) and Eden Valley (EV) (www.barossawine.com/vineyards/barossa-grounds/). The vineyard sites were divided into two sections (high, low) based on an electromagnetic induction soil survey and canopy size maps of each block, as explained in Bonada et al (2022). Vineyard age, clone, rootstock, row orientation, pruning method, and trellising system were recorded (Supplementary Table 1).…”

Benchmarking Water-Limited Yield Potential and Yield Gaps of Shiraz in the Barossa and Eden Valleys

“…K-means clustering identifes zones through minimisation of the within-cluster variance and maximisation of the diference between cluster means [39]. Vineyard age, clone, rootstock, vine and row spacing, row orientation, pruning method, and trellising system were recorded [40]. All the vineyards were drip-irrigated, with dripper spacing and fow rates varying between vineyards.…”

Grapevine Yield Big-data for Soil and Climate Zoning. A case study in Languedoc-Roussillon, France

“…Climate change is also expected to have a particularly negative impact on grape yield in warm, dry winegrowing regions such as the Mediterranean [12]. Little is known about grapevine yields at large scales, with only recent studies analyzing water-limited grapevine yield gaps in the Barossa and Eden valleys [13].…”