Golf Course Management

JUN 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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06.18 GOLF COURSE MANAGEMENT 69 ple off-type and desirable grasses on golf course putting greens. Beginning in summer 2013, 52 samples were harvested from 21 golf courses in Alabama, Arkansas, Florida, Mis - sissippi, South Carolina and Tennessee. e superintendent at each golf course determined what was an off-type and what was the desir - able grass. It is important to note that off-type grasses were found in Champion, MiniVerde and TifEagle putting greens. A plug of each sample was taken to the University of Tennes - see to be grown in a greenhouse environment for morphological and genetic characteriza - tion as well as responses to nitrogen and plant growth regulator (PGR) applications. Morphological characterization e off-type and desirable samples from putting greens were characterized accord - ing to their morphology. A single, three-node stolon of each sample was planted into a peat moss-based growing medium and maintained in a greenhouse environment. e stolon length at transplanting ranged from 1.3 to 4.4 inches (3.4 to 11.3 cm), which is an indication of the morphological and growth variability among the samples. Morphological characterization of the off- type and desirable samples was conducted using methods similar to those used by other researchers (7). Internode length and stolon diameter were measured between the third and fourth node, and leaf length and width were quantified using the outer leaf from the third node. In addition, a leaf length:width ratio was calculated. All measurements were made using digital calipers, with each grass sample replicated four times and measure - ments collected on three stolons per replica- tion (n = 12). e morphological data were an- alyzed using a cluster analysis with the goal of grouping these grasses according to the vari - ability among samples. A clustering algorithm was used to separate the data set into a defined number of clusters (that is, groups). ree clusters were determined based on a clustering criterion number and the number of observa - tions in each cluster. Cluster 1 contained nine off-type and five desirable samples. Cluster 2 had 12 off-type and 14 desirable samples. Cluster 3 had eight off-type and four desirable samples. Means for each morphological measurement of the three clusters are presented in Figure 2. Internode length, leaf length and length:width ratio were statistically different among the three clusters, Plant measurements Figure 2. Cluster means and standard deviations for internode length, leaf length, leaf length:width ratio, stolon diameter and leaf width measurements. Measurements were made on 52 off-type and desirable ultradwarf bermudagrass samples harvested from golf course putting greens in the southeastern U.S. Cluster 1 Cluster 2 Cluster 3 Cluster 1 Cluster 2 Cluster 3 Millimeters Millimeters Internode length Leaf length Leaf length:width Stolon diameter Leaf width whereas stolon diameter and leaf width were similar (Figure 2). e mean internode length for grasses in cluster 1 was 0.5 inch (12.7 mm) and 0.4 inch (9.9 mm) longer than cluster 2 or 3, respectively (Figure 2). However, leaf length was significantly longer in cluster 3 (1.2 inches or 29.9 mm) than clusters 1 (0.6 inch or 14.9 mm) and 2 (0.4 inch or 9.9 mm). is rela - tionship was also present in length:width ratio among clusters (Figure 2). Figure 3 contains a representative sample from each morphologi - cal cluster. Internode and leaf lengths varied greatly among desirable and off- type grasses as well as grasses measured in other experiments (4,7). is is an indication of the amount of

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