Thursday, November 8, 2007 - 8:00 AM

Growth Responses of Saltgrass to Combined Effects of Drought Stress and Mowing Heights.

Mohammad Pessarakli1, D.M. Kopec1, Jeffrey Gilbert1, and Anthony Koski2. (1) University of Arizona, Department of Plant Sciences, Forbes Bldg., Room 303, Tucson, AZ 85721, (2) Colorado State University, Department of Horticulture and Land Scaping, Fort Collins, CO 80523-1173

This study was conducted in a greenhouse to find the most tolerant of various saltgrass clones under drought stress, and recommendation of these clone(s) as the potential turfgrass species for use under regions with limited water supplies or drought conditions. Twelve saltgrass clones, collected from various locations, were grown in cups (9 cm diameter and 7 cm height) placed in galvanized cans (45.72 cm diameter and 55.88 cm height). Fritted clay was used as the culture medium. After six months of the establishment period (normal growth, daily irrigation, weekly fertilization and clipping at 5 cm height), the grasses were evaluated at two (5 and 2.5 cm) mowing heights for four months drought period. Three replications of each mowing height were used in a Randomized Split Plot design experiment. Weekly visual evaluations of the green canopy (percent green leaves and stems) as well as weekly shoots (clippings) harvests were made. The harvested materials were oven dried at 60o C for dry-matter (DM) weights determination. After three weeks growth under drought stress, for the drought acclimation period (mild drought stress), leaf samples were taken for the initial osmometer reading. Two months after the initiation of the drought period, the first sign of stress (leaf curling) was shown. At this stage, leaf samples were taken for the second (final) osmometer reading (osmotic adjustment stage). Grasses gradually showed more signs of wilting (finally, permanent wilting, and eventually death). The results showed a substantial variation among the tested clones. At the termination of the drought period, some clones did not survive, while some showed about 20% green canopy. Compared with the 5 cm mowing height, the 2.5 cm mowing height grasses maintained their canopy green color for longer time. However, there was no measurable growth by any plants after 3 months growth under drought stress.