Evaluation of remote sensing to measure plant stress in creeping bentgrass (Agrostis stolonifera L.) fairways

Turfgrass irrigation strategies must be clearly defined in response to increasing concerns over quality water availability. Water conservation may be achieved with technologies such as remote sensing. The objectives of this research were to (i) correlate reflectance measurements from creeping bentgrass (Agrostis stolonifera L.) under stress with volumetric water content and turf quality measurements, (ii) determine if remote sensing can detect plant stress before visual observation, and (iii) explore the influence of nitrogen fertility on water stress detection. Four experiments were conducted in the 2006 and 2007 growing seasons on 3-m² creeping bentgrass plots maintained under fairway conditions at the University of Minnesota agriculture campus. Treatments were irrigation at 20, 40, 60, and 80% of predicted evapotranspiration every 3 d on plots fertilized with 98 or 244 kg N ha^-1 yr^-1. Reflectance measurements from two remote sensors were more highly correlated (r = 0.73-0.91) than reflectance and turf quality (r = 0.42-0.71) or reflectance and volumetric water content (r = 0.28-0.64). Reflectance measurements detected water stress 0 to 48 h before visual observation across all treatments and experiments. Nitrogen did not influence the ability to detect drought-stressed turfgrass. Use of remote sensors to monitor and detect drought stress has the potential to improve turfgrass irrigation and ultimately conserve water.