Résumé
Cool-season grasses, both annual and perennial, typically employ the strategies of dehydration avoidance and dehydration tolerance to help them to survive extended periods of low soil moisture. Summer dormancy is an extra trait employed by perennial grasses particularly adapted to regions experiencing extended hot, dry summers. Of the three strategies, it appears that least is known about dehydration tolerance. Using and extending a methodology developed for cocksfoot (Dactylis glomerata L.), this study compared a range of cultivars of cocksfoot, tall fescue and phalaris differing in expression of summer dormancy. Both inter-and intra-specific variation in dehydration tolerance was observed, with cocksfoot expressing the trait strongly, whereas it was least evident in phalaris. The trait was more strongly evident in cultivars originating in drier environments, and the ability to express dehydration tolerance appeared to be independent of summer dormancy. It has been confirmed that dehydration tolerance is a powerful drought-survival trait, one that warrants increasing attention in plant breeding programs for drying environments.