*3.2. Impact of Irrigation Levels and Frequency on Turfgrass Visual Ratings*

Table 3 summarizes the statistical analysis of the VR data for both species in 2018 and 2019. Figure 4 illustrated the dynamics of VR values over time for tall fescue and hybrid bermudagrass species across the imposed irrigation treatments. The VR values greater than six were considered acceptable for residential areas and are highlighted in green.


**Table 3.** Statistical analysis of the hybrid bermudagrass and tall fescue response (visual rating) to irrigation treatments imposed in 2018 and 2019 (each year and species were analyzed separately).

NS, \*\*\* and \* are non-significant or significant at *p* ≤ 0.001 and 0.05, respectively. Means sharing a similar letter are not significantly different, based on Turkey's test at α = 0.05. I, F, and T in the table refer to irrigation levels, irrigation frequency restrictions, and time (i.e., repeated measures of visual rating each year over time), respectively.

**Figure 4.** The dynamics of visual rating (VR) values over time showing the response of hybrid bermudagrass (B) and tall fescue (TF) turfgrass to varying irrigation treatments (percentages of ETo) imposed in 2018 and 2019. d/wk: days per week.

For hybrid bermudagrass, in 2018 and 2019, the VR values ranged from 5 to 9. The effect of irrigation levels was only significant in 2018 (*p* < 0.05). Irrigation frequency restriction showed no significant impact on either of the years. The interaction of irrigation levels and frequency restrictions was not statistically significant in either of the years. In 2018 and for the 3 d wk−<sup>1</sup> frequency restriction, the VR values started to fluctuate noticeably beginning in June, yet stayed above or very close to the minimum threshold for most of the trial (Figure 4). Toward the end of the experiment, VR values fell below 6 for the 65% ETo and 84% ETo treatments. The VRs for 101% ETo treatment stayed in the acceptable range during the trial. The trend was very similar for the 2 d wk−<sup>1</sup> frequency restriction treatment. In 2019, the VRs were similar for both 7 and 3 d wk−<sup>1</sup> frequency restrictions. It showed a gradual and constant increase from VR values close to 6 up to 7–8 at the end of the trial. The dynamics of VR values over time were very similar across the irrigation levels in 2019.

For tall fescue in 2018, the VR values ranged from 4 to 9. In 2019, the VR values ranged from 3 to 8. The irrigation level (*p* < 0.001) and frequency restriction (*p* < 0.05) significantly impacted the VR values in 2018, but not in 2019. The interaction of irrigation levels and frequency restrictions was not statistically significant in either of the years. In 2018, the tall fescue VR values were higher than the minimum threshold (VR = 6) for the 129% ETo treatment and 108% ETo, except for the early July period. For the 83% ETo treatment, the VR values decreased as the trial progressed and eventually fell below the minimum accepted values of 6. The trends were similar for the 2 d wk−<sup>1</sup> and 3 d wk−<sup>1</sup> irrigation frequency restrictions. In 2019, the VR fluctuated less for the 7 d wk−<sup>1</sup> treatments (no frequency restriction), yet only stayed above the threshold for the highest irrigation treatments of 129% ETo for most of the experiment. The lowest quality ratings were observed for the irrigation level of 83%. For the 3 d wk−<sup>1</sup> restriction, all treatments had VR values below the acceptable threshold, and the 109% treatment had slightly higher VR values than the 129% treatment.
