Growth Responses, Ion Relations, and Osmotic Adaptations of Eleven C4 Turfgrasses to Salinity

Abstract

AbstractShortages of fresh water, coupled with soil salinization in many areas have resulted in an increased need for salt tolerant turfgrasses. This study was conducted to compare growth and physiological responses of eleven C4 (grasses which utilize the C‐4 carboxylic acid pathway in photosynthesis) turfgrasses to salinity. Grasses were grown in solution culture in a glasshouse, with NaCl added to achieve salinities of 0.7, 10, 20, and 30 dS m−1 (0, 99, 198, and 298 mM NaCl). Grasses were ranked for salinity tolerance according to their relative top growth reductions with increasing salinity. Tolerant grasses included a Hawaii selection of seashore paspalum (Paspalum vaginatum Swartz), two St. Augustinegrasses (Stenotaphrum secondtum Walt.), and manilagrass (Zoysia matrella L.). Bermudagrasses (Cynodon spp. (L.) Pers. Burtt‐Davey) tested were generally less tolerant to salinity. Shoot and root Na and CI concentrations reached very high levels in St. Augustinegrasses, and were relatively high in seashore paspalum and Japanese lawngrass (Zoysia japonica Steud.). In contrast, manilagrass and bermudagrasses maintained low levels of Na and Cl under high salinity which is indicative of ion regulation, due in part to efficient leaf salt glands. Seashore paspalum maintained higher shoot and root K concentrations under high salinity than did other grasses. All grasses adjusted osmotically under increasing salinity. Although St. Augustinegrasses and seashore paspalum accumulated Na and Cl in the shoots to relatively high levels, they maintained much higher tissue water levels than did other grasses, resulting in intermediate sap osmolalities.