Turfgrass Drought Response and Water Use During An Induced Drought Period.

Increasing demand and regulation of water supplies has driven a trend to identify turfgrasss species and cultivars suitable for minimal irrigation inputs. Unfortunately much of the research available regarding water use under limited irrigation scenarios focuses entirely on phenotypic responses and does not measure water use. The objectives of this study are to 1) demonstrate the applicability of a time rate of change remote sensing approach to measure evapotranspiration (ET) during a simulated drought, 2) to measure multi-depth soil water content to determine if lysimeters can effectively simulate water uptake of the entire rot zone during drought and 3) investigate a drought response presentation tool that corresponds to turfgrass ET and water extraction capabilities. The study was conducted during the 2012 and 2013 growing seasons in Madison, WI. A 12 x 12 m mobile rainout shelter was used to induce two consecutive drought conditions on  a variety of cool season turfgrasses including: Speedway, SR 8650, and Mustang 4 tall fescue, SR2100, Canon, Touche, and SR 2284 Kentucky bluegrass, SR 3150 hard fescue, SR 5130 chewing fescue, and SR 5250 and Boreal creeping fescue. Data collection included instantaneous ET, NDVI, quality, surface and multi-depth volumetric soil water content twice weekly. Kentucky bluegrass lost color faster than tall fescue, likely because of the species limited ability to extract water and the correspondng dormancy response. Multi-depth volumetric soil water content measurements revealed turfgrass use water well below a 60 cm depth, indicating most lysimeters used for ET measurement are too shallow. The use of a radiometric approach is a suitable way to measure instantaneous turfgrass ET during drought periods to monitor a turfgrasses water use during drought and the likelihood of dormancy or death. The combincation of water use and phenotypic responses is a good way to classify a turfgrasses drought response.