Genotype‐by‐environment interaction for turfgrass quality in bermudagrass across the southeastern United States

Abstract

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.

Multispecies genotype × environment interaction for turfgrass quality in five turfgrass breeding programs in the southeastern United States

“…For each species, three separate breeding nurseries (each containing different lines) were evaluated: Nursery 1 (2011–2012), Nursery 2 (2012–2013), and Nursery 3 (2013–2014). Thus, a total of 12 nurseries (three nurseries for each of four species) were established at eight locations across the southeastern United States, corresponding to research facilities from the five partnering universities: Citra and Hague, FL (UF); College Station and Dallas, TX (TAMUS); Griffin and Tifton, GA (UGA); Stillwater, OK (OSU); and Jackson Springs, NC (NCSU) (Gouveia et al., 2020). Weather data from 2011 to 2014 in these locations were presented in supplemental materials by Gouveia et al.…”

“…Weather data from 2011 to 2014 in these locations were presented in supplemental materials by Gouveia et al. (2020). Each nursery was arranged as a randomized complete block design with two replicates.…”

Evaluation of recurrent selection for drought tolerant tall fescue (Festuca arundinacea) using rain‐out shelters

“…A recent study by Gouveia et al. (2020) estimated H 2 for bermudagrass ( Cynodon spp.) turf quality under both drought and non‐drought conditions at multiple locations across southeastern United States.…”

“…Drought stress decreased broad-sense heritability (H 2 ) of root to shoot ratio from 0.47 to 0.28 and grain yield from 0.55 to 0.17. A recent study by Gouveia et al (2020) estimated H 2 for bermudagrass (Cynodon spp.) turf quality under both drought and non-drought conditions at multiple locations across southeastern United States.…”

Multilocational screening identifies new drought‐tolerant, warm‐season turfgrasses

“…This requires multiyear and multilocation testing to ensure stable performance. A recent federal grant emphasizing the development of droughttolerant, warm-season cultivars provided an opportunity for southern turfgrass breeders to evaluate a large set of diverse germplasm for drought tolerance at multiple locations across the southern United States (Gouveia et al, 2020). One of the primary goals of this collaborative effort was to rapidly and efficiently identify broadly adapted genotypes with superior drought tolerance.…”