| Abstract/Contents: | "Bermudagrasses [Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy] were the primary warm-season species used on golf greens until improved varieties of seashore paspalum (Paspalum vaginatum Swartz) and zoysiagrass (Zoysia spp.), with claims of reduced fertilizer and water requirements, became available. Nitrogen is normally applied at 4.9 g N m-2 wk-1 during warm-season putting green establishment to ensure rapid turfgrass cover. Potassium, which reduces turfgrass growth, quality, and tolerance to environmental stresses when deficient, is often applied at rates equal to or greater than N in an attempt to increase its benefits. 'TifDwarf' (TD) and 'TifEagle' (TE) bermudagrasses, 'SeaDwarf' (SD) seashore paspalum, and 'PristineFlora' (PF) zoysiagrass [Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] had varied levels of N, K, and irrigation applied to compare nutrient and water use requirements. Cultivars were sprigged at 36.6 m³ ha-1 on a USGA-specified sand research green in Sept. 2008 and July 2009. Fertilizer treatments included 1.2, 2.4, 3.7, or 4.9 g N m-2 wk-1, and a one-time application of polymer-coated urea (PCU) at 39.1 g N m-2. Each N treatment coincided with four N to K fertilization ratios (N:K): 1N:1K, 1N:2K, 1N:3K, or 1N:4K. Within cultivar grow-in rate was similar for SD,TD, and TE in both years, and PF in year 2 with 2.4, 3.7, or 4.9 g N m-2 wk-1; 1.2 g N m-2 wk-1 was similar for SD in year 2. There were no significant effects among N:K. The 2.4 g N m-2 wk-1 rate was generally considered best for rapid establishment of all cultivars. Although 1.2 g N m-2 wk-1 was usually slower to grow-in, it often provided a more desirable putting surface than 3.7, or 4.9 g N m-2 wk-1. One application of PCU provided sufficient cover for all cultivars in 2009. The USGA green was then fertilized with N at 4.9 g m-2 30d-1, and K at 1N:1K, 1N:2K, 1N:3K, or 1N:4K and irrigated at 25, 50 or 100% of potential evapotranspiration (ETo), as determined by the Blaney-Criddle equation. Treatments were initiated in April (experiment 1) and Oct. (experiment 2) 2009. All cultivars had objectionable wilting at 25% ETo, although PF and SD generally had less in exp. 2. TifDwarf and TE had objectionable wilting at 50% ETo in both exp.'s, while PF was objectionable in exp. 2. Wilting did not become objectionable at 100% ETo. There were no beneficial effects for increasing N:K. SeaDwarf appeared to tolerate deficit irrigation the best. A second water use study, which used identical irrigation treatments and lysimeters to measure evapotranspiration (ET), was conducted with PF, SD, and TD sodded on Hallandale fine sand (Siliceous, hyperthermic Lithic Psammaquent). All cultivars had objectionable wilting at 25, 50, and 100% ETo. SeaDwarf had less wilting than PF in both exp., and TD in exp. 2 at 25% ETo. TifDwarf wilted most at 50% ETo in exp. 2. PristineFlora had the highest ET, and SD the lowest. Irrigation at 100% ETo was insufficient for all cultivars on the native soil. PristineFlora and SD provided high quality putting surfaces and had better drought resistance than TD and TE bermudagrass. SeaDwarf required the least N during establishment." |
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