The influence of deciduous foliage shade on turfgrass development has not been fully investigated. Previous research neglects changes in spectral distribution, e.g., red:far‐red light (R:FR) ratios common of foliage shade. Turfgrass plants may respond simultaneously but in different ways to changes in light intensity and spectral composition. A field study was conducted in 2001–2002 at the Ohio Turfgrass Research and Educational Facility, Columbus, OH. Two tall fescue (Festuca arundinacea Schreb.) cultivars of differing shade tolerance were established under low photosynthetic photon flux (PPF) in approximately 8% of full sunlight with high (>1) and low (<1) R:FR ratios to distinguish between developmental effects of R:FR ratio (spectral composition) and PPF (light intensity) on turfgrass photomorphogenesis. Few morphological differences in shade tolerance between the two cultivars were observed during the 2‐yr study. However, under low PPF, high R:FR ratios led to increased tillering, leaf blade width and thickness, and chlorophyll contents. Root mass declined under reduced PPF regardless of R:FR ratio. Results suggest that while turfgrass photomorphogenesis in shade is influenced by changes in PPF, many characters are further influenced by changes in the R:FR ratio.

A 3-year study was conducted to evaluate the comparative performance of zoysiagrass (Zoysia spp.) cultivars for shaded environments in which inputs are minimized. Included in the study were commercial cultivars Diamond, Cavalier, Royal, Shadow Turf, Zorro, Zeon, Jamur, Crowne, Palisades, and Meyer. In July 2006, grass plugs were planted in a shade nursery comprised of live oak trees providing 89% shade. From 2007 to 2009, turf plots were periodically evaluated for quality, density, color, vertical canopy height, and extent of lateral spread. Overall turfgrass quality was noticeably reduced by the heavily shaded environment; however, some cultivars attained acceptable levels during midsummer periods. A turf performance index (TPI) was generated for ranking the cultivars that represented the number of times an entry occurred in the top statistical group across all parameters and rating dates. ‘Royal’, ‘Zorro’, and ‘Shadow Turf’ were the cultivars ranking in the top statistical grouping most often throughout the study. The results suggest that Z. matrellas may be better adapted than Z. japonicas for heavily shaded environments where inputs are conserved.

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Municipal water restrictions have become commonplace throughout much of the southern United States. The objectives of this 2‐yr study were to (i) determine supplemental irrigation requirements necessary for achieving acceptable quality in 15 zoysiagrass (Zoysia japonica and Zoysia matrella) and bermudagrass (Cynodon ssp.) cultivars when managed under a 2 d/wk irrigation frequency, (ii) determine the effects of mowing height on irrigation requirements, and (iii) evaluate root development differences between the species and cultivars at the completion of the study. A linear gradient irrigation system (LGIS) was used to provide an irrigation gradient across field plots. Plots were evaluated along the gradient six times over two summers to determine the level of supplemental irrigation, relative to reference evapotranspiration (ETo), necessary for maintaining acceptable visual quality. The fine‐textured, sports‐type bermudagrass cultivars required the least supplemental irrigation (∼10 to 15% × ETo) to maintain acceptable quality in the study. The medium‐textured amenity bermudagrasses and Japanese lawngrass (Zoysia japonica Steud.) cultivars required similar but somewhat greater irrigation requirements (∼15 to 20% × ETo) than the fine‐textured bermudagrasses. Manilagrass cultivars (Z. matrella) required the highest supplemental irrigation requirements (∼25 to 33% × ETo) for maintaining acceptable appearance within 2 d/wk irrigation regime. Mowing height did not consistently affect irrigation requirements for either group of bermudagrass but affected the Zoysia species differently. Tall mowing heights generally reduced irrigation requirements in Z. japonica but increased irrigation requirements for Z. matrella cultivars. While few intraspecific root development differences occurred within the 0 to 25 cm soil depth, Z. matrella root development was limited relative to bermudagrass and Z. japonica cultivars within deeper (25–50 cm) soil, which may have contributed to the higher irrigation requirements for the species. The results emphasize differences in supplemental irrigation levels needed for maintaining acceptable appearance among warm‐season turfgrass species and cultivars during 2 d/wk irrigation.

Estimation of genotype‐by‐environment interaction (GEI) is important in breeding programs because it provides critical information to guide selection decisions. In general, multienvironment trials exhibit heterogeneity of variances and covariances at several levels. Thus, the objectives of this study were (a) to find the best genetic covariance matrix to model GEI and compare changes in genotypic rankings between the best covariance structure against a compound symmetry structure, (b) to define mega‐environments for turfgrass performance across the southeastern United States, and (c) to estimate genetic correlations between drought or nondrought and growing or nongrowing conditions to determine the extent of GEI under specific environments. Three nurseries with 165, 164, and 154 genotypes were evaluated in 2011–2012, 2012–2013, and 2013–2014, respectively. These nurseries were conducted at eight locations (Citra, FL; Hague, FL; College Station, TX; Dallas, TX; Griffin, GA; Tifton, GA; Stillwater, OK; and Jackson Springs, NC). The response variables were averaged turfgrass quality (TQ), TQ under drought (TQD), nondrought TQ (TQND), TQ under actively growing months (TQG), and TQ under nongrowing months (TQNG). This study demonstrated that (a) the best variance structure varied among traits and seasons, and changes in genotype rankings were dependent on GEI; (b) considering TQ and TQND, mega‐environments formed between Jackson Springs and College Station, and between Citra, Dallas, and Griffin, whereas Stillwater, Hague, and Tifton represented unique environments across the southeastern United States; and (c) genetic correlations between drought or nondrought and growing or nongrowing conditions suggested that indirect selection can be efficient in multienvironment trials for contrasting environmental conditions.