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.

Genotype selection for physiological responses of drought tolerance using molecular markers in polycross hybrids of orchardgrass

“…The higher values of genetic variation for ratio of Chla to Chlb (Chla/Chlb), CAR content, PRO and WSC under drought stress conditions, suggested that environmental changes can increase genetic variation of these traits and help adjust the regulation of plant growth and metabolism to the new environment (Xu et al, 2016). Our results showed that drought stress reduced the values of forage yield and Chla, Chlb and TChl content (Chla, Chlb, TChl), which is evidently due to reduced water potential, stomatal conductance, transpiration, photosynthetic rates and dry matter accumulation (Merewitz, Meyer, Bonos, & Huang, 2010;Saeidnia et al, 2018). Increased Chla/Chlb under water stress indicated that Chlb is more sensitive to drought stress than Chla (Ashraf & Harris, 2013;Saeidnia et al, 2018).…”

“…Our results showed that drought stress reduced the values of forage yield and Chla, Chlb and TChl content (Chla, Chlb, TChl), which is evidently due to reduced water potential, stomatal conductance, transpiration, photosynthetic rates and dry matter accumulation (Merewitz, Meyer, Bonos, & Huang, 2010;Saeidnia et al, 2018). Increased Chla/Chlb under water stress indicated that Chlb is more sensitive to drought stress than Chla (Ashraf & Harris, 2013;Saeidnia et al, 2018). Accumulation of proline (PRO) and WSC is a common adaptation mechanism acquired by perennial grasses under drought stress (Pirnajmedin, Majidi, & Gheysari, 2015;Saeidnia et al, 2018;Volaire, Moore, & Moser, 1997).…”

“…Orchardgrass is a high quality forage grass naturalized to temperate climates (Jiang & Huang, ; Saeidnia, Majidi, Mirlohi, & Ahmadi, ). It is a self‐incompatible, outcrossing species and cultivars are usually produced through random mating of several selected parents using the polycross method resulting in population‐based synthetic cultivars (Sanada, Gras, & Santen, ).…”

“…Grass species respond and adapt to drought stress through change in morphological and physiological characters (Bahrani, Bahrami, & Kamgarhaghighi, ). There is evidence that phenotyping using physiological traits, as a complement to agronomic traits, may help in identifying selectable features that accelerate breeding for yield potential and performance under drought stress (Fleury, Jefferies, Kuchel, & Langridge, ; Pozo et al, ; Saeidnia et al, ).…”

“…phenotyping using physiological traits, as a complement to agronomic traits, may help in identifying selectable features that accelerate breeding for yield potential and performance under drought stress (Fleury, Jefferies, Kuchel, & Langridge, 2010;Pozo et al, 2016;Saeidnia et al, 2018).…”