S-Abscisic Acid Effects on Evapotranspiration and Leaf Burn in Salvia farinacea

摘要

In a series of experiments with Salvia farinacea 'Rhea Deep Violet' under high air temperatures and light levels, s-abscisic acid (S-ABA) was evaluated for reducing evapotranspiration rates (ET) and for the potential side effect of injury due to high leaf temperatures. Plants were sprayed with S-ABA at a range of 125 to 1000 mg?L~(-1) and then moved to a simulated retail environment under full sun (811 to 941 W?m~(-2)), 30% shade, or 57% shade. Injury was rated on a scale of 1 (no burn) to 5 (extensive burn), with an injury rating of 3 considered unmarketable. On 15 June, 2010 (maximum air temperature 36.7°C) ET for plants in full sun sprayed at 1000 and 125 mg?L~(-1) was 35% and 80% of control plants. For plants sprayed at 1000, 125, and 0 mg?L~(-1) midday leaf temperatures were 37.7, 31.0 and 26.3°C and injury ratings were 5.0, 2.8, and 1.0, respectively. On 12 May (maximum air temperature of 30°C) ET in full sun for plants treated at 1000 and 125 mg?L~(-1) was 20 and 66% of control plants. For plants in 1000, 125, and 0 mg?L~(-1) treatments, leaf temperatures were 31.8, 27.5, and 24.1°C and injury ratings were 3.5, 1.0, and 1.0, respectively. On 2 June (maximum air temperature 33°C), plants treated with 1000 mg?L~(-1) and held in either full sun, 30% shade, or 57% shade had leaf temperatures of 36.9, 34.0, and 32.0°C and received injury ratings of 3.8, 1.2, and 1.0, respectively. There was a significant multiple variant correlation for amount of injury with S-ABA concentration and air temperature. These results with S. farinacea indicate that to reduce the risk of injury from high tissue temperatures under hot conditions users should either apply lower concentrations of S-ABA or the plants should not be displayed in full sun.