Drought Tolerance of Turf Bermudagrasses Under Greenhouse Conditions.

Twenty bermudagrass (Cynodon species) cultivars were evaluated for visual quality, leaf firing resistance and percent live green cover during exposure to an extended drought as well as during an extended recovery period. Grasses were grown in 7.6 cm wide by 76 cm deep tubes of calcined clay. The mowing height was 5 cm. The experiment was replicated three times in a poly covered greenhouse at Oklahoma State University at Stillwater, OK during 2009 through 2010. Lengths of the drought cycles were 93, 101 and 67 d, with recovery cycles of 151, 86 and 65 d in Experiments I through III. Celebration (drought tolerant) and Premier (drought sensitive) bermudagrasses were selected as standards of comparison based on previously published research. In Experiments II and III percent volumetric soil moisture was measured at an average 5, 10, 38 and 71 cm depths using a TDR probe. The visual parameters quality, leaf firing and living cover were strongly and positively correlated in all experiments during drydown and recovery cycles. Drought resistance as measured by living cover varied greatly amongst the twenty bermudagrasses in each experiment. In general, Celebration showed the highest resistance to drought by resisting leaf firing and loss of live cover the longest during drydown and by recovering faster after the drought. Premier showed lower drought resistance as indicated by more rapid leaf firing and earlier loss of live cover. TifGrand performed nearly as well as Celebration in drought while Latitude 36 had leaf firing and live cover performance similar to Premier. Generally, Celebration, TifGrand and other cultivars with higher drought resistance had improved moisture extraction capacity at deeper soil depths. Cultivars with earlier leaf firing and loss of live cover had higher levels of moisture remaining deep in the soil profile during the drought.