Physiological responses of drought tolerance in orchardgrass (Dactylis glomerata) in association with persistence and summer dormancy

Abstract

The genetic basis of physiological responses to drought and its association with productivity, persistence and summer dormancy is not clear in orchardgrass (Dactylis glomerata L.). Thirty-six orchardgrass genotypes were evaluated under water stress and non-stressed conditions during 2 years (2013–14). High genotypic variation was observed for all of the agronomic and physiological traits. Water stress reduced dry matter yield, relative water content and chlorophyll content while significantly increasing carotenoids, water-soluble carbohydrates, proline and chlorophyll a : b ratio. The results indicated that carotenoids and proline accumulation could not be used for discriminating drought-tolerant genotypes of orchardgrass, whereas water-soluble carbohydrates may be used to achieve this purpose. Moreover, the results showed that the stable genotypes that have lower changes in productivity from normal to water-stress environments also have more persistence. No association was found between summer dormancy and drought tolerance measured by both physiological and yield-based drought-tolerance indices. Some of the drought-tolerant genotypes had relatively high persistence and better autumn recovery, a characteristic useful for the development of new synthetic varieties.