Leaf anatomical responses and chemical composition of warm-season turfgrasses to increasing salinity

Abstract

As population growth and demands for potable water increase, use of low-quality or effluent sources of irrigation is becoming more prevalent. Because these water sources often contain elevated levels of dissolved salts, turfgrasses must increasingly possess mechanisms for coping with salinity stress. The objectives of this research were to utilize Scanning Electron Microscopy (SEM) combined with Energy Dispersive X-ray Spectroscopy (EDS) to explore and characterize anatomical and physiological responses of four salinity-tolerant cultivars/experimental lines of warm-season turfgrass species including bermudagrass (Cynodon ssp.), zoysiagrass (Zoysia ssp.), St. Augustinegrass (Stenotaphrum secundatum), and seashore paspalum (Paspalum vaginatum) to salinity stress. Grasses were grown in the greenhouse under two levels of salinity stress (control = 2.5 and 30 dS m−1) prior to examination of adaxial and cross-sectional leaf surfaces using SEM and EDS. St. Augustinegrass leaf anatomy did not differ between control and elevated salinity. In bermudagrass, salt glands were observed at the 30 dS m−1 salinity level, however, none were detected at the 2.5 dS m−1 level. Zoysiagrass appeared to possess constitutive salt gland development, which although were present under 2.5 dS m−1 salinity, noticeably increased in density with increasing salinity. Seashore paspalum did not possess salt glands, but rather, exhibited bladder-like structures, in which EDS detected high levels of Na following salinity stress. These findings highlight differences in anatomical responses to salinity stress among warm-season turfgrass species. The information may aid breeders and physiologists in developing a more comprehensive understanding of warm-season turfgrass anatomical responses to salinity stress.