Drought Resistance of Warm‐Season Putting Green Cultivars on U.S. Golf Association Root Zones with Varied Potassium

Abstract

Drought resistance of putting green cultivars is receiving increased attention due to irrigation restrictions. Potassium, which reduces turfgrass tolerance to environmental stresses when deficient, is often applied at rates equal to or greater than N in an attempt to increase its efficacy. Drought resistance for recently established ‘TifDwarf’ (TD) and ‘TifEagle’ (TE) bermudagrasses [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt Davy], ‘SeaDwarf’ (SD) seashore paspalum (Paspalum vaginatum Swartz), and ‘PristineFlora’ (PF) zoysiagrass [Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] was evaluated under varied irrigation and K levels on a U.S. Golf Association (USGA)‐specified research green. Irrigation treatments were applied in the spring and fall of 2009 and spring 2010, and included 25, 50, and 100% of potential evapotranspiration (ETo), as calculated using the Blaney–Criddle equation. Nitrogen at 4.9 g m−2 30 d−1 and K (as KCl) in 1N:1K, 1N:2K, 1N:3K, and 1N:4K fertilization ratios were applied at the beginning of each experiment. All cultivars had objectionable wilting (>10%) at 25% ETo in 2009, although PF and SD had least in the fall. In 2010 PF and SD did not exhibit objectionable wilting at any irrigation level. At 50% ETo, TD and TE wilted objectionably in all experiments, as did PF in the fall of 2009. In 2010, the bermudagrasses exhibited objectionable wilting under daily irrigation at 100% ETo. Increasing K in relation to N failed to increase drought resistance for the cultivars studied. The bermudagrasses had the least drought resistance and PF and SD the most.