High Throughput Phenotyping of Turfgrasses for Drought Tolerance.

     Drought is characterized by a steady decrease in plant available moisture in the soil and a decline in tissue water content. Plants have developed three major strategies for living with drought, including, avoidance, tolerance and escape. Our objective was to evaluate high throughput screening methods in a greenhouse to identify drought tolerance among genotypes of different grasses. Six genotypes of each of the three genera, Stenotaphrum Trin. (St. Augustinegrass), Poa L. (Bluegrass), and Zoysia Willd. (Zoysiagrass ), were grown in a synthetic clay medium and planted randomly among their own genus in three separate but identical containers. Drought tolerance was assessed using digital image analysis, turgid weight/dry weight ratios, leaf electrolyte leakage, canopy temperature readings, clipping weights and turf quality ratings. Plants were re-watered when the bottom of the growing medium reached 10 % volumetric water content and parameters were recorded for an additional 3 weeks to gain an understanding of the recovery traits of these grasses.  All plants exhibited symptoms of osmotic stress including leaf firing, wilting, reduced shoot growth, color changes and higher canopy temperatures. Digital image analysis was used to objectively classify phenotypes under water deficit conditions. This study demonstrated the advantages of several phenotyping methods and parameters. The information gathered will be useful in developing future drought tolerant grass varieties.