Effects of elevated temperature in grapevine. I Berry sensory traits

Background and Aim Thermal decoupling results from the differential effect of temperature on the many components of biological systems from molecular to ecosystem scales. We tested the hypotheses that elevated temperature decouples berry sensory traits, and that this effect is cultivar-dependent. Methods and Results We assessed 20 sensory traits in berries from a factorial field experiment combining two temperature regimes (elevated temperature and control) and four cultivars (Cabernet Franc, Chardonnay, Semillon and Shiraz) over two thermally contrasting seasons in the Barossa Valley. The thermal response had two elements: offset, which accounts for the average advancement (or delay) across traits, and decoupling, which measures the scatter in the response of the different traits. Large decoupling was generally associated with large offset (e.g. Cabernet Franc), but large decoupling was also observed with minor offset (e.g. Semillon). Two types of decoupling were identified: decoupling mostly driven by differential response between seed and other berry components, and decoupling with a dominant variation in traits within berry parts. Conclusion Elevated temperature decoupled berry sensory traits, and this effect was cultivar- and season-dependent. Significance of the Study Awareness of the magnitude and type of decoupling would likely contribute to viticultural and winemaking adaptations in warmer regimes.