Modelling heatwaves in viticultural regions of southeastern Australia

Crop responses to environmental stress are multidimensional. First, there is a biological dimension whereby responses to stressors depend on the nature, timing, intensity and duration of stress, and previous growing conditions. Crops have species-specific time windows when critical yield components are particularly susceptible to stresses (Andrade et al. 2005; Dunn 2005; Sadras 2007). Yield losses associated with extreme temperatures often relate to injury of reproductive structures including pollen grains, egg cells and ovules (Jain et al. 2007; Yang et al. 2007). Acclimatisation processes have been identified for extreme temperatures (Hubackova 1996; Wang and Li 2006) and other stresses (Amzallag 1996; Moulia et al. 2006; Wikbergi and Ogreni 2007; de Langre 2008). Second, location, topography and time of the year converge to determine a site and time-specific pattern of climatic conditions with potentially stressful effects on crops. For instance, the likelihood of a certain water deficit is directly linked to the patterns of rainfall and evaporative demand (Rodriguez and Sadras 2007; Sadras and Rodriguez 2007), whereas frost and heat risk are related to the tails of the frequency distributions of temperatures (Snyder and MeloAbreu 2005). Modelling heatwaves in viticultural regions of southeastern Australia