Physiological responses to salinity in turfgrass

Critical freshwater shortages are occurring in urban population centres worldwide. Overuse of freshwater resources, coupled with effects of global warming such as salt water intrusion and desertification are resulting in salinization of water and soil resources. Many governments have responded by placing restrictions on the use of freshwater for irrigating turfgrass landscapes, instead requiring use of secondary saline water sources. Progress has been made in understanding turfgrass salinity tolerance mechanisms, and in development of salt tolerant turfgrass cultivars and alternate native species. Turf-type grass species show extreme range in salt tolerance, from salt-sensitive to seawater tolerant. Salinity tolerance in turfgrass species is associated with stimulated root, and sometimes shoot growth under moderate salinities, resulting in increased root/shoot ratios. Shoot saline ion regulation, coupled with minimal yet complete osmotic adjustment, is a key salinity tolerance mechanism in grasses. In Chloridoid grasses, which include most C4 turfgrasses, ion regulation is largely achieved by leaf salt gland excretion. Under saline conditions, osmotic adjustment in turf-type grass species is achieved predominately with saline ions, compartmentalized in vacuoles. Of potential compatible solutes, only glycinebetaine accumulates to levels sufficient for cytoplasmic osmotic adjustment in these species.