Wednesday, November 15, 2006

Comparison of Turfgrass Visual Quality Ratings with Ratings Determined Using the GreenSeeker Handheld Optical Sensor.

Kyungjoon Koh, Gregory Bell, Dennis Martin, and Holly Han. Oklahoma State University, 360 Ag Hall, Stillwater, OK 74078-6027

Turfgrass performance can be assessed in terms of visual and functional quality. Visual quality is the performance trait most often utilized in large cultivar performance trials.  Evaluators assessing turfgrass visual quality may be distracted by many factors that affect accuracy and consistency.  The objectives of this study were to assess the GreenSeeker Handheld optical sensor for evaluating overall turfgrass quality in three turf species over two growing seasons, and to compare the combined time required of visual evaluation and data entry with the time required for the same functions using a handheld optical sensor.  Visual quality ratings and sensor ratings were collected on schedules prescribed by the National Turfgrass Evaluation Program for the 2002 bermudagrass, the 2002 buffalograss, and the 2002 zoysiagrass studies in 2003 and 2004.  The sensor ratings were collected within 24 hours of when visual ratings were assessed by an experienced visual evaluator.  Use of the sensor reduced the time required to complete data collection and data entry by 68% compared with visual evaluation.  The strongest relationship between ratings collected by the visual evaluator and the sensor were from those collected on Bermudagrass (r2=0.51 in 2003; n=­­­­­­­­­­­­­­­­­­­­­­­ 1029 and r2=0.76 in 2004; n=1029).  The relationship between the two assessment methods was stronger in the spring and fall than in the summer because more difference occurred between the cultivars and quality differences were more easily observed by both rating methods.  The GreenSeeker Handheld sensor provided a consistent, objective evaluation of turfgrass quality and required considerably less time than visual evaluation.

Handout (.pdf format, 72.0 kb)