Root physiological and biochemical responses of seashore paspalum and centipedegrass exposed to iso‐osmotic salt and drought stresses

Abstract

AbstractDrought and salt are two major stresses of turfgrass. Both damage the plant root system by disrupting osmotic balance at the root–soil interface. The objectives of our hydroponic experiments were to understand root physiological and biochemical responses in two turfgrass species (seashore paspalum [Paspalum vaginatum Swartz] and centipedegrass [Eremochloa ophiuroides (Munro) Hack.]) with distinct salinity tolerance exposed to iso‐osmotic drought and salt stresses. Two seashore paspalum genotypes, ‘Seastar’ and ‘UGP113’, and a centipedegrass genotype, ‘TifBlair’, were exposed to three treatments: control, salt stress (−0.4 MPa by adding NaCl), and drought stress (−0.4 MPa by adding polyethylene glycol). Although equal in osmotic potential, drought stress damage was more evident compared with salt stress in terms of lipid peroxidation and decreased root viability in all three turfgrass genotypes. Salt stress reduced root viability only in the centipedegrass genotype, indicating ion toxicity effects in this turfgrass genotype. Seashore paspalum genotypes had greater total accumulation of Na+ and K+ for greater root osmotic adjustment than centipedegrass under salt stress. Seashore paspalum genotypes also had greater activities of root antioxidant enzymes such as superoxide dismutase, peroxidase, and glutathione reductase compared with centipedegrass under salt stress. In contrast, centipedegrass had greater total accumulation of total soluble sugar and proline for greater osmotic adjustment compared with seashore paspalum genotypes under drought stress. Despite greater accumulation of organic osmolytes, activities of superoxide dismutase, catalase, peroxidase, and glutathione reductase in centipedegrass were either lower or similar to those in seashore paspalum genotypes, and therefore centipedegrass accumulated similar oxidative damage as seashore paspalum genotypes under drought stress.