Deficit irrigation of cool and warm season turfgrass varieties under sub-drip irrigation method

The aim of this study is to determine the effects of deficit irrigation applications at different levels on the cool-season and warm-season turfgrass species irrigated by subsurface drip irrigation. Field experiments were conducted in the Agricultural Production and Research Center (TURAM) of Silivri Municipality in Gümüşyaka District located between the boundaries of Tekirdağ and Istanbul-TURKEY, at growing season 2020. In this research, two different turfgrass types (K: Cool season turfgrass and B:Warm season turfgrass), at three different irrigation threshold (S1: Full irrigation, S2: 1/3 deficiency, S3: 2/3 deficiency) were examined in split-plots in randomized blocks design with three replications. During the experimental season 28 times and 23 times irrigation were applied for cool and warm season turf varieties, respectively. Irrigation water applied for cool season turfgrass types in different irrigation strategies varied between 559,9 mm - 196,5 mm, seasonal evapotranspiration values varied between 771,2 mm - 4 13,9 mm, and daily evapotranspiration values varied between 5,8 mm/day - 3,1 mm/day. As for warm-season turfgrass types the same values varied between 464,8 mm - 167,7 mm; 575,4 mm - 451,0 mm, and 4,3 mm/day - 3,4 mm/day, respectively. In the 5-months period (May-June-July, August and September) the amount of seasonal irrigation water were 16% less in the warm season turfgrass than that of cool season turfgrass. When seasonal actual evapotranspiration values were compared, it was observed that it was 34% more in cool-season turfgrass than in warm-season turfgrass. Average CWSI values calculated for different irrigation treatments were 0,10-0,35 for cool-season turf, 0,10-0,26 for warm-season turf besides, average CWSI values before irrigation application were 0,12-0,49 for cool-season turf, 0,13-0,38 for warm-season turf. Changes in the vegetation height, fresh yield, dry yield, plant density, color, and quality properties were monitored depending on the irrigation levels. When parameters mentioned above are evaluated together full irrigation treatment gave the best quality for both grass varieties. But, S2 treantment for both varieties, which supplied acceptable quality, has suggested to save ırrigation water of 1/3. Besides, Blaney-Criddle method and Penman-Monteith method were chosen as the best equation for cool and warm season turf types, respectively, and crop coefficient (kc) curves were prepared for both turfgrass species.