Water allocations to turfgrass in Arizona are being restricted, and this trend will increase in the future. As water restrictions increase, secondary, low quality water sources are being substituted for turfgrass irrigation, resulting in increased environmental stress (drought, salinity, and heat). My research focus is in these areas:
1) Elucidating drought and salinity tolerance mechanisms of turfgrasses, and alternative grass species. The predominant turfgrass used in the southwest is bermudagrass, and current cultivars are derived from a narrow genetic base. There are a number of other bermuda (Cynodon) species, as well as other possible alternative xerophytic and halophytic grasses which are being investigated.
2) Determining minimum water use requirements of turfgrass germplasm. Little is known about the minimum water requirements of most important turfgrasses in the southwest. Linear gradient irrigation and lysimetry are being used at the Karsten Turfgrass Laboratory to determine minimum water requirements and evapotranspiration rates under deficit irrigation.
3) Developing methodologies for rapid screening of turfgrass germplasm for heat tolerance. Currently there is a strong interest in developing heat tolerant C3 turfgrasses for golf courses in the southern U.S. Turfgrass breeders are currently using field selection techniques for this trait, which are time-consuming, inefficient, and expensive. Several recently-developed laboratory techniques are being developed which may be able to predict whole-plant heat tolerance.
Marcum, K.B. 1998. Cell membrane thermostability and whole-plant heat tolerance of Kentucky bluegrass. Crop Science (38:1214-1218).
Marcum, K.B., S.J. Morton, and M.C. Engelke. 1998. Salt gland ion secretion: A salinity tolerance mechanism among five zoysiagrass species. Crop Science (38:806-810).
Marcum, K.B. and H. Jiang. 1997. Effects of plant growth regulators on tall fescue rooting and water use. J. Turfgrass Mgmt. 2(2):13-27.
Marcum, K.B. 1995. Salinity tolerance mechanisms of grasses in the subfamily Chloridoideae. p. 231-237. In M.A. Salt Tolerant Plants. Book Crafters, MI.
Marcum, K.B., M.C. Engelke, S.J. Morton, and R.H. White. 1995. Rooting characteristics and associated drought resistance of zoysiagrass. Agron. J. 87:534-538.
Marcum, K.B., M.C. Engelke, and S.J. Morton. 1995. Rooting characteristics of buffalograsses grown in flexible plastic tubes. HortScience 30(7):1390-1392.
Marcum, K.B. and C.L. Murdoch. 1994. Salinity tolerance mechanisms of six C4 turfgrasses. J. Amer. Soc. Hort. Sci. 119:779-784.
Marcum, K.B. and C.L. Murdoch. 1992. Salt tolerance of the coastal salt marsh grass, Sporobolus virginicus (L.) kunth. New Phytol. 120:281-288.
Marcum, K.B. and C.L. Murdoch. 1990.
Salt glands in the Zoysieae. Ann. Bot. 66:1-7.