A window into hotter and drier futures: phenological shifts and adaptive practices

Abstract

Temperature is one of the main environmental factors influencing vine physiology, berry composition and wine attributes. However, much of our understanding on the effects of temperature on vine physiology and berry composition has been gained from experiments under controlled conditions.

Summary

This project belongs to Program 3 Grapes for Purpose, with a dominant element of Vine Performance and some elements of Berry Composition. The key strategy is “Collaborative investments in vine physiology” and the measure of success is “A better industry understanding of temperature, water and vine relationships”. Against this background, three major R&D needs had been identified:

(i) Scaling-up to the 3-way interaction between heat, water and variety.

(ii) Variety-dependent tools for in-season prediction of ripening for logistic purposes, i.e. harvest, transport and winery scheduling, and irrigation planning.

(iii) Viticultural practices to reduce heat damage.

This project had four objectives:

Enabling objectives:

1. To quantify the responses of Shiraz vines and wines to the combined effects of high temperature and water deficit under realistic vineyard conditions.

2. To quantify variety-dependent responses to high temperature and the interaction between temperature and fruit load per unit canopy size.

Practical objectives:

3. To develop user-friendly, robust models for variety-specific prediction of maturity. This will assist in harvest and winery scheduling, reduce costs, and help irrigation trusts in planning regional demand accounting for shifts in phenology and peak demand of irrigation water.

4. To develop management guidelines with emphasis on the interaction between heat stress, water supply and fruit load per unit canopy size.