Desmostachya bipinnata manages photosynthesis and oxidative stress at moderate salinity

Desmostachya bipinnata is a C-4 grass distributed in arid-saline lands of the subtropical region. There are many economic usages of this perennial grass ranging from folk-medicine to cattle-fodder. However, information regarding the mechanism of salinity tolerance of this species is rare. This study examines the effects of salinity (0, 200 and 400 mM NaCl) on growth, osmotic relations, photosynthesis and antioxidant defense. Salinity caused progressive decrease in fresh weight; however, dry weight decreased only at 400 mM NaCl. Leaf sap osmotic potential and xylem pressure potential decreased while quantities of ash, proline and sugars increased in response to salinity increments. Stomatal conductance, photosynthetic CO2 gain and transpiration decreased with increasing salinity, while intercellular CO2 levels remained unaffected. Maximum and actual quantum yield of PS II and electron transport rate were inhibited with enhanced non-photochemical quenching under high salinity. Levels of superoxide dismutase and total phenols increased, those of guaiacol peroxidase and ascorbate peroxidase remained unaltered and catalase increased transiently at 200 mM NaCl. Leaf hydrogen peroxide and malondialdehyde content increased with salinity. Our data suggest that D. bipinnata could maintain photosynthesis and manage oxidative stress at moderate salinity but a further increase in salinity compromised both photosynthesis and the antioxidant system. (C) 2016 Elsevier GmbH. All rights reserved.