Water relations and drought tolerance of four turfgrasses

Greenhouse studies were conducted on three warm-season turfgrasses, 'Midlawn' bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy], 'Prairie' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], and 'Meyer' zoysiagrass (Zoysia japonica Steud.), and a cool-season turfgrass, 'Mustang' tall fescue (Festuca arundinacea Schreb.) to determine 1) water relations and drought tolerance characteristics by subjecting container-grown grasses to drought and 2) potential relationships between osmotic adjustment (OA) and turf recovery after severe drought. Tall fescue was clipped at 6.3 cm once weekly, whereas warm-season grasses were clipped at 4.5 cm twice weekly. The threshold volumetric soil water content (SWC) at which a sharp decline in leaf water potential (psi(L)) occurred was higher for tall fescue than for warm-season grasses. Buffalograss exhibited the lowest and tall fescue exhibited the highest reduction in leaf pressure potential (psi(P)) per unit decline in psi(L) during dry down. Ranking of grasses for magnitude of OA was buffalograss (0.84 MPa) = zoysiagrass (0.77 MPa) > bermudagrass (0.60 MPa) > tall fescue (0.34 MPa). Grass coverage 2 weeks after irrigation was resumed was correlated positively with magnitude of OA (r = 0.66, P < 0.05).