Ecophysiology of salinity tolerance in three halophytic turfgrasses

[Truncated abstract] Growth and physiological mechanisms of salt tolerance in three halophytic turfgrasses (Distichlis spicata, Sporobolus virginicus and Paspalum vaginatum) and a non-halophyte (Pennisetum clandestinum) were studied. Field experiments were conducted at a site in Western Australia with plots irrigated either with saline groundwater (13.5 dS m-1) or potable water, to assess changes in soil salinity and responses of the turfgrass species. Glasshouse experiments further characterised physiological responses to high levels of salinity. Key questions addressed by this study regarding the use of saline irrigation water were: (i) Will build up of salts in the soil have adverse effects on growth and quality of turfgrass, and what irrigation volumes are required to best manage salt accumulation? (ii) Will halophytic grasses prevent large increases in Na+ and Cl- concentrations in leaf tissues and thus retain high leaf colour, as compared to the non-halophyte, as a major criterion for salinity tolerance? (iii) Will turfgrass water use by the halophytes be maintained under saline irrigation, whereas declines in water use are expected for the non-halophyte if suffering from salinity stress? (iv) After salts are leached out of the root-zone by autumn/winter rains, how well can the halophytic and non-halophytic turfgrasses recover? In a field experiment, saline water ECw of 13.5 dS m-1 and potable water were used to irrigate replicated plots of the four species. Changes in soil salinity were evaluated; ECsoil solution was ~6.5 dS m-1 prior to saline irrigation and increased gradually to ~ 40 dS m-1 by mid-summer, and growth of the non-halophyte was severely reduced.