Measuring Summer Dormancy of Perennial Grasses in Contrasting Environments

The summer dormancy trait has been shown to confer enhanced levels of survival to temperate perennial forage species over long periods of intense summer drought (Volaire and Norton 2006) and is therefore valuable in plant improvement. Normally found in species endemic to drier Mediterranean climates it is recommended that the trait be measured in the field under typical Mediterranean hot, dry summer conditions (Norton et al. 2008). However, this trait has potential utility in regions with summers that can receive substantial rainfall, but still experience extended periods of intense moisture deficit. Therefore, it is important to determine whether summer dormancy expression can be reliably measured in environments cooler and moister than those considered typically Mediterranean. This paper compares the measurement of summer dormancy across a range of three commercially important temperate perennial grass species when undertaken in typical Mediterranean summer conditions and in a cooler and wetter summer environment