Effects of ground temperature regulation on the soil temperature, quality, and root growth of bentgrass turf under heat stress

To explore the mitigation effects of ground temperature regulation on turf heat stress, three different treatments were set at the soil depth of 20 cm with 27, 24, and 21 ℃. The bentgrass turf maintained under normal growth conditions was used as the control, and the effects of temperature on turf soil temperature, quality, and root system were explored. During the high-temperature season, ground temperature regulation significantly reduced turf soil temperature (P < 0.05), alleviated the decline in turf quality, and recovered root growth under heat stress. Moreover, these mitigation effects reached statistical significance when the temperature was maintained below 24 ℃ (P < 0.05), with the best cooling effect observed at 21 ℃. Soil temperature at 5 and 20 cm was reduced by respectively 2～4.5 and 5～7 ℃ under the 21 ℃ cooling treatment compared with that under the control treatment. Additionally, under the same treatment, the turf color and normalized difference vegetation index were increased by respectively 17.8% and 28.2%. Likewise, the underground biomass, total root length, root surface area, root volume, and root vitality of the turf were increased up to 58.2%, 84.5%, 97.8%, 112.7%, and 46.9%, respectively. Therefore, ground temperature regulation effectively alleviated the decline in bentgrass turf growth under heat stress, and this strategy can effectively improve bentgrass survival during high-temperature seasons. Specifically, maintaining the ground temperature at 21～24 ℃ is the most suitable mitigation strategy.