Golf Course Management

JUN 2013

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research Spring green-up and fall color retention in 2005, 2006 and 2007 Spring green-up Cultivar 2005 Fall color retention 2006 2007 Mean 2005 2006 2007 Mean Drip Sprinkler Drip Sprinkler Drip Sprinkler A138 5.1a† 5.4a 2.8b 2.7a 1.0 1.0b 3.0ab 2.9e 5.4d 4.3e 4.2e De Anza 3.7bA 2.9cB 2.3cA 1.6cB 1.0B 1.6aA 2.2c 3.1e 5.4d 4.4de 4.3e DT16 5.4a 5.7a 3.4aA 2.9aB 1.0 1.0b 3.2a 5.6ab 6.8c 5.9a 6.1b Princess 77 5.3aA 4.2bB 2.1c 1.8bc 1.0 1.0b 2.6bc 5.0cd 7.6b 5.1b 5.9bc Riviera 3.6b 3.2c 2.1c 2.0b 1.0 1.0b 2.1c 4.7d 7.4b 4.9bc 5.7bc NuMex Sahara 3.7bA 2.7cB 2.1c 2.1b 1.0 1.0b 2.1c 4.7d 6.7c 4.7bc 5.4d Sea Spray 5.2aA 4.3bB 1.7dA 1.1dB 1.0 1.0b 2.4bc 5.9a 8.3a 5.7a 6.7a SeaDwarf 5.0aA 4.2bB 1.4d 1.2cd 1.0 1.0b 2.3c 5.3bc 8.6a 5.8a 6.6a Transcontinental 3.2b 2.7c 2.3c 2.1b 1.0 1.0b 2.1c 4.9cd 6.8c 4.5cde 5.4cd Mean 4.5A 3.9B 2.3A 1.9B 1.0 1.1 † Values followed by the same letter are not signifcantly different from one another. Lowercase letters denote differences between cultivars separately for each year (in columns); uppercase letters denote differences between drip and sprinkler irrigation separately for each cultivar and year. Table 3. Spring green-up and fall color retention (from 1 = complete dormancy to 9 = plot entirely green) of nine turfgrasses in 2005, 2006 and 2007. Data for spring green-up are pooled over three water qualities (potable, moderately saline, and saline) and listed separately for drip and sprinkler irrigation. Values represent an average of nine readings (three water qualities and three replications). Data for fall color retention are pooled over three water qualities (potable, moderately saline, and saline) and two irrigation systems (drip and sprinkler irrigation). exhibited lower quality than the same grasses on sprinkler-irrigated plots, whereas only one cultivar had lower quality on drip-irrigated plots at the beginning of the study. Fall quality on drip-irrigated De Anza plots was also lower than on sprinkler-irrigated plots, but all other grasses showed no difference in quality between the two irrigation systems. When data were averaged over the three years of the study, SeaDwarf (7.8) exhibited the highest fall quality and DT16 (5.3) and A138 (5.0) had the lowest (Table 2). Spring green-up and fall color retention Inland saltgrass DT16 was the fastest to green up in the spring, followed by A138. Riviera, NuMex Sahara, SeaDwarf and Transcontinental were slowest to green up (Table 3). When data were averaged over all cultivars, drip-irrigated plots were faster to green up than sprinkler-irrigated plots in 2005 and in 2006. In 2007, no difference in speed of green-up between the two irrigation systems was observed (Table 3). Sea Spray rated highest for fall color retention during all three years, joined by Sea Dwarf and DT16 in two of the three years. A138 and De Anza were the frst grasses to go dormant as evidenced by the lowest fall color ratings in each of three years of the study (Table 3). Fall color retention was not affected by water quality or irrigation system. Among the bermudagrass cultivars, Princess 77, Riviera and Transcontinental had greater fall color retention than NuMex Sahara. Correlations among turf quality and salinity Summer values of EC, sodium and SAR in the 86 GCM June 2013 top 4 inches of the root zone were not good predictors of summer quality. No signifcant relationship between any of the salinity parameters and turf quality could be established for saltgrasses A138 and DT16 or seashore paspalum SeaDwarf and Sea Spray. Although soil EC had a signifcant effect on the quality of De Anza and Princess 77, the correlation was very low, indicating that little of the variation in quality could be explained by variation in soil EC. There was also a signifcant relationship between EC and sodium content and summer quality of Riviera and Transcontinental, but again, little of the variation in quality could be explained by variation in soil EC and sodium content. Discussion EC and sodium content Irrigating turfgrasses with saline waters requires careful root-zone management to prevent detrimental levels of salt accumulation. Adding a leaching fraction to the required irrigation amount, blending irrigation water or alternating sources of irrigation water have all been suggested as strategies to manage salinity accumulation (2,3,5,6). In this study we added a leaching fraction (irrigation was applied at 110% ETo) and relied on natural precipitation to manage salinity in the top 8 inches of the root zone. Consequently, seasonal changes in soil EC and sodium content followed the irrigation and natural precipitation pattern, with higher values during the dry periods of the summer followed by lower values after the summer rains. During the three-year study, EC and sodium content were highest in summer 2005 and 2006

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