Irrigation scheduling based on Crop Water Stress Index (CWSI) for cool and warm-season turf grass under subsurface-drip irrigation method

Özet

Aims: This study was conducted to determine irrigation scheduling based on the Crop Water Stress Index (CWSI) of cool (CS) and warm-season (WS) turfgrass species under subsurface-drip irrigation method. Methods and Results: The field experiment was carried out during the summer period of 2018 in the Agricultural Production and Research Centre (TURAM) of Silivri municipality, Istanbul-Turkey. Specific objectives were to measure actual evapotranspiration (ETc) values for both turfgrass types, to compare their responses to different water levels, to determine CWSI values for both turfgrass species under different irrigation scheduling and opportunity of using CWSI in irrigation timing, to compare ETc with reference to evapotranspiration (ETo) calculated with five different methods and to determine crop coefficient curve (kc) for experimental conditions, and to focus on the crop growing and irrigation management parameters under subsurface-drip irrigation method. Three irrigation strategies [I1:30%, I2:50%, and I3:70%) were tested in a split-plot randomized complete block design with three replications. These strategies corresponded, respectively, to 30%, 50% and 70% of total available soil moisture depletion at 0-30 cm of the effective root zone and returning soil moisture back to field capacity. The results indicated that colour, quality, fresh yield, dry matter yield, irrigation water use efficiency, water use efficiency, vegetation height and mowing were significantly different in terms of irrigation strategies for both species. The most appropriate irrigation strategies were I2:50% for CS and I3:70% for WS turfgrass which corresponded to a CWSI of 0.47 and 0.45, respectively. Conclusions: The amount of applied irrigation water in WS turfgrass was 53% less than in CS turfgrass. Actual evapotranspiration was 26% lower for WS than for CS turfgrass. Significance and Impact of the Study: These results obtained from the experiments will help choosing of turf type and irrigation scheduling to save water in urban areas.