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In turfgrass breeding, drought resistance is a primary trait for improvement due to scarcity and reduced quality of water for irrigation. Therefore, in 2010, the turfgrass breeding programs at six public universities joined efforts to address these challenges by cross evaluating breeding lines for the most economically significant warm‐season turfgrass species in the southern United States through a United States Department of Agriculture‐National Institute for Food and Agriculture Specialty Crop Research Initiative funded project. Three breeding cycles were associated with three completed (2010–2014, 2014–2019, and 2019–2024) collaborative grant projects, but the efficiency of this partnership in terms of gains from selection has not been measured. Our objectives were to (1) estimate the expected and realized genetic gain for drought resistance and turfgrass quality for three breeding cycles, (2) compare cultivars developed with support of the projects versus standard cultivars in a historical data analysis, and (3) compare genetic gain for traits assessed visually versus using small unmanned aircraft systems imagery, both in drought and non‐drought environments. For these purposes, historical data were investigated with a retrospective analysis of project trials evaluated 2011–2024. Our findings for the realized genetic gain demonstrated progress in enhancing drought resistance in bermudagrass, St. Augustinegrass, seashore paspalum, and zoysiagrass. In addition, notable positive increments for this trait were documented for each cycle compared to the standard cultivars, particularly in bermudagrass, St. Augustinegrass, and zoysiagrass. While heritability was higher for visually assessed traits, genetic increments were more pronounced for imagery‐assessed traits. [ABSTRACT FROM AUTHOR]

Little is known about the variation of 2C nuclear DNA content in zoysiagrass (Zoysia Willd.). Therefore, a glasshouse study including 20 cultivars and 16 experimental genotypes of Zoysia japonica Steud., Z. macrantha Desv., Z. matrella (L.) Merr., Z. minima (Colenso) Zotov, Z. pacifica (Goudswaard) M. Hotta & Kuroki, Z. pauciflora Mez, and select interspecific hybrids was conducted in 2008 at Gainesville, FL. Nuclei were stained with propidium iodide, and flow cytometry (FCM) analysis was conducted with a laser cytometer. Genotypes from Z. minima and Z. matrella had the largest (0.96 pg) and smallest (0,77 pg) 2C nuclear DNA content, respectively. The observed 0.19 pg spread between zoysiagrass species was less than variation reported in other tetraploid warm-season grasses within the same species. Results further suggest that midparent values for 2C nuclear DNA content of interspecific hybrids between Z. minima and other Zoysia spp. may be statistically detectable. Zoysiagrasses have one of the smallest genome sizes but are extremely diverse with respect to morphology, growth habit, and response to abiotic and biotic stresses. This information supports the large genome constraint hypothesis that species with small genome sizes are better able to adapt to environmental changes due to a lack of evolutionary limitations associated with large amounts of repetitive DNA. doi: 10.2135/cropsci2009.08.0425

Common carpetgrass [Axonopus fissifolius (Raddi) Kuhlm.] is a perennial, warm-season grass. Its low maintenance attributes make it a desirable turfgrass species for use in the southeastern United States. Information on the extent of genetic diversity at the molecular level for common carpetgrass germplasm is limited. Accordingly, the objectives of this study were to assess the genetic diversity and relatedness among 59 common carpetgrass accessions, including 48 accessions collected from the southeastern United States, one from Hawaii, one from the NPGS, and another nine derived from commercial seed (seed-derived) using fluorescence-labeled amplified fragment length polymorphism (AFLP) markers. Twenty selected AFLP primer combinations generated a total of 1046 amplification bands, of which 469 (44.1%) were polymorphic. Genetic similarity coefficients among accessions ranged from 0.807 to 0.980. A low level of genetic diversity (Shannon's information index = 0.24, gene diversity = 0.16) was observed for this collection. Naturalized accessions had relatively higher genetic diversity than seed-derived accessions. Accessions from both sources were randomly distributed throughout the dendrogram with no definite geographic or source patterns. More comprehensive sampling throughout its center of origin is needed to increase the genetic diversity of common carpetgrass for breeding. doi: 10.2135/cropsci2009.08.0472

Sting nematodes (Belonolaimus longicaudatus) can injure roots of many warm-season turfgrasses in sandy, welt-drained soils and on artificial, sand-based putting greens. Resistant or tolerant grasses could reduce the need for chemical control. This research was initiated to assess the host status and relative tolerance of six warm-season genotypes--four zoysiagrasses (Zoysia Wiild.), one St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and one bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy]-to the sting nematode by two screening methodologies in sequential glasshouse trials in 2007. All entries were hosts with final sting populations 1.7 to 11.0 times greater than initial inoculation levels. Results indicate that evaluating root lengths of unestablished sprigs under sting nematode pressure may improve the identification of genotypes with greater genetic tolerance than in methods using established plants. Total root lengths were not reduced by sting nematodes in UFZ-10, indicating greater tolerance than found in other entries. Treatments of 'Empire', 'Cavalier', 'Emerald', ,TifEagle', and 'Floratam' inoculated 45 d after planting exhibited total root length reductions of 24, 29, 29, 32, and 37%, respectively, when compared with uninoculated controls, The observed variability suggests that gains from selecting for sting nematode resistance or tolerance are possible in zoysiagrass. doi: 10.2135/cropsci2008.11.0672

Zoysiagrasses (Zoysia spp.) are widely adapted and highly variable; however, information is lacking regarding the heritability and potential for improvement of numerous performance characteristics. Three individual replicated field studies, which included 90 very fine, 108 fine, and 126 coarse-textured zoysiagrass genotypes, respectively, were conducted near Gainesville, FL, to determine the response and broad-sense heritabilities of 10 turfgrass performance and stressrelated characteristics. Genotypic variance largely contributed to the wide range in expressed phenotypic response for plot coverage, turf density, turf quality, genetic color, and seedhead density, which resulted in higher broad-sense heritability estimates (0.62 [less than or equal to]_[H.sup.2][less than or equal to] 0.94). Fall dormancy and spring greenup were influenced more by the environment and had lower heritabilities (0.32[less than or equal to] [H.sup.2][less than or equal to] 0.58). Turf quality was also rated considering the effects of glufosinate [2-amino4-(hydroxymethylphosphinyl)butanoic acid] herbicide application, Bipolaris incidence, and mole cricket (Scapteriscus spp.) damage. Large error variances and low broad-sense heritablities were typical for these stress-related traits. Potential exists for improvement of characteristics that exhibited large amounts of genetic variation and were less influenced by the environment. Broadsense heritability estimates indicate the possibility of combining desirable traits in superior clonalty propagated [F.sub.1] hybrids. doi: 10.2135/cropsci2008.12.0705

Common carpetgrass (Axonopus fissifolius Raddi) is a stoloniferous, sod-forming species used sparingly as a turfgrass. No information is available regarding the relationships between germplasm accessions of this species. Accordingly, the initial objective of this study was to evaluate the relatedness of common carpetgrass germplasm for morphological and turfgrass performance traits. This was accomplished using principal component and cluster analysis. Resulting principal components were separated into related traits that influenced plant architecture, aesthetic appeal, and inflorescence characteristics. The secondary objective was to identify if collection location impacted genotype performance. This was completed by arranging genotypes into groups on the basis of their geographic origin within the collection area and subsequently analyzing the groups to determine if collection location impacted growth and performance. Differences were found for winter color, establishment, and seedhead density between the SE group and other groups (SW, NE, and NW) which were not different from each other. Groups refer to regions; specifically, SE represents south of 31[degrees] N latitude and east of 86[degrees] W longitude, SW represents south of 31[degrees] N latitude and west of 86[degrees] W longitude, NE represents north of 31[degrees] N latitude and east of 86[degrees] W longitude, and NW represents north of 31[degrees] N latitude and west of 86[degrees] W longitude.

Carpetgrass (Axonopus fissifolius Raddi) is a warm-season perennial grass species that may warrant improvement for use as a turfgrass in the southeastern United States and lower latitudes. Limited information is available regarding the types and amounts of variation that exists for this species. Research objectives were to collect germplasm, to determine the variation for morphological and turfgrass performance characteristics, and to estimate heritability. Germplasm was derived from commercial seed and collection trips. Experiments were performed in both greenhouse and field conditions. The greenhouse study evaluated morphological traits, and the field study evaluated turfgrass performance characteristics. Differences in means were found to exist between genotypes for most traits. Heritability estimates were low to high, indicating the potential to alter stolon diameter, internode length, leaf length and width, spike number per inflorescence, inflorescence density, establishment, genetic color, density, and turf quality through conventional breeding. Differences in means and variances were found to exist between the two germplasm sources (seed-derived and collected) for some traits. For morphological traits, the seed-derived material exhibited greater variation than collected material. However, for turfgrass performance, traits of the collected genotypes were more variable than seed-derived plants.

Cynodon transvaalensis Burtt-Davy (African bermudagrass) is used as a turfgrass and in interspecific hybridization to produce turfgrass cultivars. Information is lacking on the magnitude of intraspecific genetic variation for traits related to turfgrass performance. A Design II mating population comprised of 320 [F.sub.1] plants (4 parental sets, 16 crosses [set.sup.-1], 5 [F.sub.1] hybrids [cross.sup.-1]) was used to estimate genetic parameters for 21 traits. The [F.sub.1] plants were evaluated in replicated field (13 traits) and greenhouse (8 traits) experiments in Stillwater, OK during 2002-2003. Genetic variation was detected for 17 of the 21 traits as indicated by significant (P < 0.05) differences among families within sets. Both additive and dominance genetic effects were detected for most of the 17 traits, but dominance effects usually prevailed over additive effects. Broad sense heritability estimates varied from 0.42 to 0.96. Population improvement via recurrent selection techniques would be possible but difficult as indicated by low levels of additive genetic variation for genetic color, raceme number, seed number, and percent seed set. Dominance effects might be exploited to select clonally propagated [F.sub.1] hybrid cultivars with enhanced sensor-rated color, density, turf quality, spring greenup, fall dormancy, percent living cover, raceme number, raceme length, number of florets per inflorescence, plant height, stolon length, number of internodes, internode length, and leaf length.

Climate change, recurrent droughts, and increasing urban water demands have limited water availability in urban landscapes. Water quantity challenges have led to irrigation restrictions and turfgrass removal programs. An experiment was conducted at the University of Florida, West Florida Research and Education Center, Jay, FL, to evaluate the effect of turfgrass conversion to other landscape types on nutrient leaching and groundwater recharge. In April 2021, all surface vegetation was removed from existing turfgrass plots using a sod harvester. Thereafter, plots were planted or covered with three landscape types: a pollinator landscape with flowering forbs (Mimosa sp., Coreopsis sp., and Phyla sp.) + turfgrass (Eremochloa ophiuroides); a nitrogen (N)‐efficient lawn (Arachis glabrata + Paspalum notatum); and a low‐input landscape with unplanted woodchip mulch. Undisturbed turfgrass (E. ophiuroides) served as a control. For 2 years, leachate samples were collected weekly from previously installed 168‐L drainage lysimeters for NO3‐N and NH4‐N load determination. Temporal changes in landscape composition, groundwater recharge, water use, and soil bulk density were also quantified. While the mulch leached 44.7 kg ha−1 NO3‐N year−1, this landscape still offers positive attributes, including erosion protection and water conservation. Conversely, the pollinator landscape minimized nitrogen leaching (8.3 kg ha−1 NO3‐N year−1) due to their relatively greater water use rates (3.56 mm day−1). The turfgrass and nitrogen‐efficient lawn returned ∼35% of the water inputs as groundwater recharge while maintaining relatively low nitrogen leaching (3.6 and 2.7 kg ha−1 NO3‐N year−1, respectively), making these landscapes efficient for protecting both water quality and quantity. [ABSTRACT FROM AUTHOR]

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] is indigenous to the short-grass prairies of North America and is a polyploid series of diploid, tetraploid, and hexaploid individuals. It has a base chromosome number of x = 10. The distribution pattern of these ploidy levels is not well-defined, especially in the southern Great Plains. We predicted the ploidy levels of 273 buffalograsses from the southern Great Plains of North America using flow cytometry to measure cellular DNA content. The buffalograss accessions were grouped into four distinct ploidy level groups. Very few diploid accessions were collected (2.6% of the collection), and all were found in northwest Texas and eastern New Mexico. Tetraploid accessions (23% of the collection) were found exclusively in the western regions of the southern Great Plains. Hexaploids were the most prevalent ploidy level, representing 73% of the collection and found throughout the collection area. Pentaploid accessions were also found in field sites (1.8% of the collection). No clear pattern of adaptation for ploidy levels is apparent from these data. In other collections, cold hardiness appears associated with higher ploidy levels, but this pattern is not apparent in the southern Great Plains., BUFFALOGRASS is a warm-season perennial grass that has been the subject of substantial plant breeding and development work in recent years for use in forage and low-maintenance turfgrass areas. Buffalograss [...]

Since its introduction into the United States in 1892, zoysiagrass (Zoysia spp. Willd.) has made a tremendous impact on the US turfgrass industry. Three species of zoysiagrass [Z. japonica Steud., Z. matrella (L.) Merr., and Z. pacifica (Goudswaard) M. Hotta & S. Kuroki] collected from East Asia and the Pacific Islands were introduced into the United States and are used directly as turf or by turfgrass breeders in the development of advanced lines. Golf courses, lawns, grounds, sod farms, athletic fields, roadsides, and airports are some of the many locations where zoysiagrass is used. While almost 50 improved cultivars of zoysiagrass have been developed to date, active efforts to improve zoysiagrass further and expand its utilization are ongoing. These continued improvements in stress and pest tolerance allow for expanded use of this low-input turf species. This review summarizes the history of zoysiagrass in the United States; summarizes species introduction and utilization; addresses and discusses strengths and shortcomings of the species; evaluates breeding history, methodology, and challenges; and suggests future prospects and potential for zoysiagrass. [ABSTRACT FROM AUTHOR]