Performance and recovery of turfgrasses irrigated with varying crop coefficients

Abstract

Deficit irrigation is a water conserving practice that involves watering below an estimated evapotranspiration (ET) replacement level. Research is limited to comparing cool-season (CS) and warm-season (WS) turfgrass varieties grown in arid regions under varying deficit irrigation replacement levels. This study investigated the effects of five levels of reference evapotranspiration for short grass (ET_OS) replacement (55%, 70%, 85%, 100%, and 115%) on the performance and fall recovery of several turfgrasses in the southwestern United States. Three years of field research evaluated green cover and visual quality of three CS Kentucky bluegrass (Poa pratensis L.) (four cultivars), tall fescue [Schedonorus arundinaceus (Schreb.)] (three cultivars), and perennial ryegrass (Lolium perenne L.) (three cultivars), and two WS turfgrasses bermudagrass (Cynodon dactylon L.) (three cultivars) and buffalograss Buchloe dactyloides (two cultivars). CS grasses required higher ET_OS replacement than WS grasses to maintain acceptable quality (1–9, ≥6 = minimum acceptable) and coverage. Among CS grasses, Barserati Kentucky bluegrass maintained the best quality and green cover under deficit irrigation and demonstrated the most consistent ability to recover. Notably, bermudagrass performed well under deficit irrigation, maintaining acceptable visual quality and better green cover than CS species like Kentucky bluegrass and tall fescue at lower irrigation levels. Overall, there were significant differences among cultivars, demonstrating the importance of the selection process in drought tolerance. These findings support the promotion of drought-resistant WS grasses to conserve water in arid regions without compromising turfgrass functionality. Future research should focus on variable and seasonal ET_OS for irrigation of turfgrasses and estimating irrigation requirements.