Forage grasses and turfgrasses are increasingly being subjected to salinity stress, due to accelerated salinization of irrigated agricultural lands worldwide, and to increased use of reclaimed and other secondary water sources for irrigating turfgrass landscapes. The objective of this study was to examine salinity responses of a number of important forage and turfgrass genera in the subfamily Chloridoideae in attempt to gain understanding of salinity tolerance mechanisms operating in this subfamily. Grasses were exposed to salinities up to 600 mM NaCI in solution culture. Salinity tolerance decreased in the following order: Distichlis spicata vat. stricta (Tort.) Beetle Sporobolus ai roides (Tort.) Tort. Cynodon da ctyion (L.) Pe ts. = Zoysia ja ponica Steud. > Sporobolus cryptandrus (Tort.) A. Gray. Buchlo~ da ctyloldes (Nutt.) Engelm. Bouteloua cu rtipendula (Michx.) Tort. Relative root length (RL) and relative root weight (RW) increased under saline conditions, relative to control, in salt tolerant grasses. Leaf sap osmolality, Na +, Cl-, and proline concentrations were negatively correlated and glycinebetaine was positively correlated with salinity tolerance. Bicellular salt glands were observed on leaves of all species. Salinity tolerance was positively correlated with Na + and CI-salt gland secretion rates. Within the subfamily Chloridoideae, salinity tolerance was associated with saline ion exclusion, facilitated by leaf salt gland ion secretion, and with accumulation of the compatible solute glycinebetaine.

The need for salt-tolerant turfgrasses is ever-increasing. Rapid urban population growth has put enormous pressures on limited freshwater supplies. Many state and local governments have reacted by placing restrictions on the use of potable water for irrigating turfgrass landscapes, instead requiring use of reclaimed, or other secondary saline water sources. In coastal areas, overpumping, and resultant salt water intrusion of coastal wells used for irrigating turfgrass facilities has widely occurred. The nature and extent of the salinity problem, followed by basic salinity issues and available management choices, will be discussed. Issues facing the turf manager using saline water sources are soil salinization, resulting in direct salt injury to turf, and secondary problems of loss of soil structure ensuing from sodium and bicarbonate effects, resulting in loss of salt leaching potential and soil anaerobiosis. Management choices for the turf manager using saline water are limited. Soil salinity must be maintained below the level deemed detrimental to the turf, by maintaining sufficient leaching. Sodium/bicarbonate affected soils must be managed to maintain sufficient permeability to permit adequate leaching. Finally, salt tolerant turf species/cultivars must be used. Long-term solutions to the salinity problem will require development of improved salt-tolerant turfgrasses. Progress in cultivar development, and future development of potential alternative halophytic turfgrass species will also be discussed. Media summaryRapid urbanization has resulted in escalating salinity issues facing turfgrass landscapes. The extent of the salinity problem, salinity management issues, including soil salt-leaching and sodicity-permeability management, use of salt tolerant turf cultivars, and future development of salt tolerant turfgrasses will be discussed.

Physiological responses to salinity and relative salt tolerance of six C4 turfgrasses were investigated. Grasses were grown in solution culture containing 1, 100, 200, 300, and 400 mm 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 mm salinity. Bermudagrass cv. Tifway (Cynodon dactylon × C. transvaalensis Burtt-Davey) was intermediate in tolerance, shoot growth being reduced 50% at ≈270 mm 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 mm 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 mm) 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 mm at 400 mm 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.

Heat stress is often a major problem in C3 (cool‐season) turfgrasses during summer months, resulting in reduced turf quality and stand loss. Current germplasm screening for heat tolerance relies on field and whole‐plant techniques, which are often inefficient and insensitive due to environmental interactions. A rapid, accurate procedure allowing simultaneous screening of large numbers of genotypes is needed. In vitro cell membrane thermostability (CMT) has been determined for a number of plants. The objectives of this study were to determine if differences in CMT exist among cultivars of Kentucky bluegrass (Poa pratensis L.), and if CMT can predict whole‐plant heat tolerance of these cultivars. CMT was determined by subjecting leaf segments to progressive heat shock exposure times, and deriving cellular electrolyte leakage curves. Whole‐plant heat tolerance was determined by subjecting plants to 41°C day/34°C night at 95% relative humidity for 62 d (Study 1) and 47 d (Study 2) in controlled‐environment chambers. Relative percentage leaf firing and percentage shoot dry weight were determined weekly. CMT was negatively correlated with relative percentage leaf firing (r = −0.80) and positively with relative percentage shoot dry weight (r = 0.75), averaged over two experiments. CMT and whole‐plant heat tolerance used as indicators demonstrated that cultivars BM‐3 and Midnight were more heat tolerant than Lavang, Nugget, and Ryss. This is the first report showing that CMT can predict whole‐plant heat tolerance among turfgrass cultivars. Being rapid, accurate, and requiring little space, CMT may offer turfgrass breeders an ideal method for screening large numbers of genotypes for heat tolerance.