DIFFERENTIAL THERMAL-ANALYSIS OF ST AUGUSTINEGRASS

The objective of this study was to relate the lethal freezing temperat ures of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] ge notypes, as measured by differential thermal analysis (DTA), to winter survival observed in the field, DTA-predicted lethal temperatures of 14 St. Augustinegrass genotypes ranged from -7.7 to -4.7C. Regression of field winter survival vs. DTA-predicted lethal temperatures resulte d in an r(2) = 0,57 for one field trial that evaluated cultivars with a relatively narrow range of expected freezing tolerance, In a second study evaluating cultivars with a greater range of freezing tolerance, r(2) was 0.92 when winter survival was regressed on DTA-predicted let hal temperatures. DTA was successful in measuring freezing avoidance o f St. Augustinegrass cultivars.