Abstract: This research investigated the effect of exogenous salicylic acid (SA) on the cold tolerance of seashore paspalum (Paspalum vaginatum), cultivar “Platinum”. A pre-treatment of 1 mmol·L^-1 SA was applied to plants in pots and after 5 days, turf quality, leaf electrolyte leakage (EL), malondialdehyde (MDA) content, antioxidant enzyme activity (superoxide dismutase, SOD; peroxidase, POD; catalase, CAT), fatty acid content and an index of unsaturated fatty acid occurrence, were determined. There were three temperature treatments: optimal temperature (30 ℃/25 ℃, day/night), chilling (8 ℃/4 ℃) and freezing (2 ℃/-2 ℃), and four replicates for SA treated and untreated pots/swards. The results showed that turf quality was adversely affected, and leaf electrolyte leakage (EL), MDA content and SOD, POD and CAT activity were increased under the chilling and freezing temperature treatments. Pre-treatment with exogenous SA significantly alleviated the detrimental effect of chilling and freezing stress on the plant growth, turf quality, EL, MDA content and antioxidant enzyme activity. The saturated fatty acid content was increased, and unsaturated fatty acid content and the index of unsaturated fatty acid occurrence were decreased under chilling and freezing temperature treatments; while pre-treatment with exogenous SA diminished these chilling and freezing effects, compared to those seen in pots not receiving SA. These results indicate that one factor in the SA-enhanced cold tolerance of seashore paspalum is the maintenance and/or increase in unsaturated fatty acid content and the index of unsaturated fatty acid occurrence, which would in turn enhance membrane stability and contribute to the observed enhancement of chilling and freezing tolerance.

Key words: seashore paspalum (Paspalum vaginatum), low temperature stress, salicylic acid, fatty acid, antioxidant enzyme activity