Response of cool and warm season turfgrass species to deficit irrigation under sprinkler and subsurface drip irrigation methods.

The aim of this study is to determine the effects of deficit irrigation applications at different levels on 
the cool-season turf mix and warm-season turfgrass species irrigated by sprinkler irrigation method and 
sub-drip irrigation method. Field experiments were conducted in the Agricultural Production and 
Research Center (TURAM) of Silivri Municipality in the boundaries of Tekirdağ and Istanbul - 
TÜRKİYE (41°03ʹN; 28°00ʹE; 46 m a.s.l.) in the summertime of 2019 and 2020. In this research, two 
different irrigation methods (SI: Sprinkler and SDI: sub-drip), for two different turfgrass types (CS: 
Cool-season turfgrass mix and WS: Warm-season turfgrass), at three different irrigation levels (I1: full 
irrigation, I2: 1/3 deficiency, I3: 2/3 deficiency) were examined in split split plots in randomized blocks 
design with three replications. Soil moisture content was monitored via TDR for irrigation scheduling, 
climatic data needed for ETo estimation were taken from automatic meteorology station established in 
experimental area, canopy temperature for CWSI calculation was measured by infrared thermometer. 
When the results were evaluated in terms of irrigation methods, 6-36% less irrigation water was applied 
with SDI method according to SI method due to the high-water application efficiency and low 
evaporation.  Besides, it has been concluded that deficit irrigation for cool season turfgrass mix has not 
been possible by SI method whereas deficit irrigation of 1/3 can be applied by SDI method on the 
condition of a little bit compromising the color quality. Thus, 38% irrigation water saving was achieved 
by SDI method. Although there was no any decrease in the density value, irrigation deficiency was not 
possible due to the decrease in the color parameter in Bermudagrass under SI method. However, 
irrigation water deficiency of 1/3 can be managed without any problem in visual quality in the same 
grass type under SDI method. Thus, approximately 50% irrigation water saving can be achieved 
compared to the SI method. 
Moreover, the CWSI is a valuable tool for monitoring and quantifying water stress and scheduling 
irrigations. CWSI of 0,12; 0,13; 0,31 and 0,39 are irrigation thresholds for CS and WS under SDI method 
for CS and WS under SI method, respectively. 
 
Keywords: Landscape irrigation, Turfgrass varieties, Irrigation methods, Irrigation water saving, Crop 
water stress index (CWSI) 
This Project was funded by The Scientific and Technological Research Council of Turkey 
(TÜBİTAK).