Salinity Tolerance Mechanisms of Six C4 Turfgrasses

Abstract

Physiological responses to salinity and relative salt tolerance of six C 4 turfgrasses were investigated. Grasses were grown in solution culture containing 1, 100, 200, 300, and 400 m m NaCl. Salinity tolerance was assessed according to reduction in relative shoot growth and turf quality with increased salinity. Manilagrass cv. Matrella (FC13521) ( Zoysia matrella (L.) Merr.), seashore paspalum (Hawaii selection) ( Paspalum vaginatum Swartz), and St. Augustinegrass (Hawaii selection) ( Stenotaphrum secundatum Walt.) were tolerant, shoot growth being reduced 50% at ≈400 m m salinity. Bermudagrass cv. Tifway ( Cynodon dactylon × C. transvaalensis Burtt-Davey) was intermediate in tolerance, shoot growth being reduced 50% at ≈270 m m salinity. Japanese lawngrass cv. Korean common ( Zoysia japonica Steud) was salt-sensitive, while centipedegrass (common) ( Eremochloa ophiuroides (Munro) Hack.) was very salt-sensitive, with total shoot mortality occurring at ≈230 and 170 m m salinity, respectively. Salinity tolerance was associated with exclusion of Na + and Cl - from shoots, a process aided by leaf salt glands in manilagrass and bermudagrass. Shoot Na + and Cl - levels were high at low (100 to 200 m m ) salinity in centipedegrass and Japanese lawngrass resulting in leaf burn and shoot die-back. Levels of glycinebetaine and proline, proposed cytoplasmic compatible solutes, increased with increased salinity in the shoots of all grasses except centipedegrass, with tissue water levels reaching 107 and 96 m m at 400 m m salinity in bermudagrass and manilagrass, respectively. Glycinebetaine and proline may make a significant contribution to cytoplasmic osmotic adjustment under salinity in all grasses except centipedegrass.