Physiological Responses and the Dust Retention Ability of Different Turfgrass Mixture Ratios Under Continuous Drought

Drought is one of the main environmental disturbances limiting the growth and production of turfgrass in China and around the world. To study the performance under drought conditions of different mixing ratios (<i>Lolium perenne</i> L., <i>Festuca elata</i> Keng., <i>Poa pratensis</i> L.), a water-controlled pot experiment was conducted. The mixing ratios used were 2:3:5, 2:6:2, and 2:2:6 for <i>Lolium perenne</i>, <i>Festuca elata</i>, and <i>Poa pratensis</i>, respectively. The relative water content (RWC), proline (Pro) content, and other physiological and ecological variables of three turfgrass monocultures and their three ratio mixtures (a total of six different treatments) were measured under drought as well as dust stress at various time points. The results revealed that, under drought stress, the dust retention performance of the mixing ratio treatments was better than the monocultures, with the best performance in the 2:6:2 mix and the worst in the <i>Poa pratensis</i> monoculture. Additionally, during the 21 days of drought stress, as time increased, the appearance quality (TQ) of the turfgrass gradually declined over time; its RWC gradually decreased; its chlorophyll (Chl) content, peroxidase (POD) activity, and superoxide dismutase (SOD) activity all showed a trend of initially increasing then decreasing; and its soluble sugar (Sol), malondialdehyde (MDA), and Pro content increased continuously. A comprehensive evaluation of physiological and ecological variables, using the membership function method, showed that the six types of turfgrass treatments ranked as follows (from strongest to weakest) in drought resistance: 2:6:2 mix > <i>Festuca elata</i> monoculture > 2:3:5 mix > 2:2:6 mix > <i>Lolium perenne</i> monoculture > <i>Poa pratensis</i> monoculture. The dust retention capability was assessed through quantitative measurements, and the ranking of dust retention amounts in descending order was as follows: <i>Festuca elata</i> > 2:6:2 mix > 2:2:6 mix > <i>Poa pratensis</i> > <i>Lolium perenne</i> > 2:3:5 mix. We conclude that, in practical applications, the degree of drought can be appropriately controlled within a certain range to achieve maximum dust retention benefits from turfgrass.