Abstract Limited availability of water resources, especially in the Southwest of the United States, has affected the turfgrass industry in recent years. Irrigating turfgrasses with marginal‐quality water conserves potable water supplies. This study evaluated lines of bermudagrass ( Cynodon Rich. spp.), St. Augustinegrass [ Stenotaphrum secundatum (Walter) Kuntze], seashore paspalum ( Paspalum vaginatum Sw.), and zoysiagrass ( Zoysia Wild. spp.) under saline water irrigation. Experiments were conducted in a greenhouse (30 dS m − 1 ) and in the field (4.4 dS m − 1 ) from 2021 to 2023. Variation in response to salinity stress expressed as changes in turfgrass quality and leaf firing was observed within all four species in the greenhouse study and within bermudagrass, St. Augustinegrass, and zoysiagrass in the field. Genotypic means for bermudagrass turfgrass quality (scale 1–9, 9 = highest) ranged from 4.5 to 9.0 in the greenhouse and from 2.67 to 6.33 in the field. Means for zoysiagrass ranged from 1.4 to 7.9 in the greenhouse and from 2.67 to 7.0 in the field. Means for St. Augustinegrass ranged from 1.0 to 7.0 in the greenhouse and from 1.0 to 6.67 in the field. Moderately strong rank correlations in turfgrass quality under stress and during recovery in the field and greenhouse were observed only for zoysiagrass (0.38–0.54). This was caused by differences in performance of individual lines in other species. Wide range of salt tolerance in bermudagrass, zoysiagrass, and St. Augustinegrass indicates that further improvement of these species is possible, providing turfgrass managers and homeowners with better‐adapted to marginal quality water cultivars.

Zoysiagrasses ( Zoysia spp.) are popular warm-season turfgrass species for home lawns, landscapes, and golf courses in the southern United States due to their lower input needs. However, persistent drought conditions necessitate the development of new cultivars with reduced irrigation requirements. This research addresses this critical need through a multi-institutional, collaborative breeding project supported by USDA-NIFA Specialty Crops Research Initiative grants. The primary objective was to improve drought tolerance in zoysiagrass, bridging a gap in the availability of resilient turfgrasses. Our approach involved multi-environment testing across the southern United States coupled with advanced phenotyping techniques, including the integration of small unmanned aircraft systems (sUAS) to collect visual (red, green, blue) and multispectral imagery. A regression analysis identified significant genetic gains for turfgrass quality under drought, with a noteworthy 10.4% increment per breeding cycle. This collaboration led to the successful commercialization of several new cultivars—including Brazos™, CitraZoy®, and Lobo™—which consistently outperformed industry standards like Zeon and Palisades in turfgrass quality and drought resistance. These new cultivars exhibit improved establishment rates, disease resistance, and wider geographical adaptability. In conclusion, this research confirms that multi-institutional collaboration, combined with the strategic adoption of sUAS-based phenotyping and advanced data analysis, is a powerful and efficient strategy for turfgrass breeding. The successful development and release of these superior cultivars provides environmentally sustainable options for a wide range of applications, offering significant benefits to both producers and consumers by reducing irrigation needs.

Centipedegrass, Eremochloa ophiuroides [Munro] Hack., is a low-maintenance, warm-season turfgrass commonly grown in the southeastern United States. Limited information is known about the genomic regions that control centipedegrass traits, including stigma color. Stigma color can impact seed set and can have a role in insect pollination in other plant species. In this study, we used a genome-wide association study to detect a genomic region on the Hi-C genome assembler (HIC-ASM)-8 found to control stigma color. Examination of the most associated single-nucleotide polymorphic (SNP) markers revealed that plants with a homozygous C/C allele had mainly purple stigmas but could be white or a mixture of colors, whereas accessions that were T/T for these loci had only white stigmas. Two candidate genes, ctg780.162 and ctg780.158, with homologs involved in anthocyanin accumulation, were identified near the most significant SNPs. The entire ctg780.158 gene was sequenced from multiple accessions, and the white stigma accessions contained a large insertion before the start codon. Similarly, white accessions (TT) had three SNPs in the ctg780.162 coding region as compared to purple accessions (CC). This study identified candidate genes for stigma color and characterized the utilization of the ctg780.158 insertion.

light conditions induce shade avoidance responses in plants, causing morphological changes that are undesirable for turfgrass aesthetic quality and plant health. A greenhouse experiment was conducted to examine the effect of varying shade intensities on hybrid bermudagrass (Cynodon dactylon x Cynodon transvaalensis) canopy morphology. Five hybrid bermudagrasses were evaluated for their shade avoidance responses to four levels of shade. Grasses were established as plugs within 20-cm-long growth tubes made from capped sections of 10-cm-diameter polyvinylchloride pipe. The grasses were maintained under ambient greenhouse conditions for 6 weeks before implementing the shade treatments for 8 weeks using a black poly-woven fabric to reduce the photosynthetic photon flux by 0%, 30%, 60%, and 90% of the ambient conditions. Leaf elongation rate was measured weekly during the shade period. The leaf area index (LAI), specific leaf (RWC), leaf angle, and leaf width were measured at the end of 8 weeks of shade treatment. Significant differences were observed in morphological parameters, which varied with the relative shade resistance of the genotypes within species. The genotype-by-treatment interaction was not significant for most of the parameters, suggesting that most grasses responded in a similar manner to shade, but that genetic behavior in their growth habit had a stronger influence on apparent resistance. 'ST-5' (TifGrandVR) had the greatest LAI, SLA, LWR, and LAR, which suggests its apparent shade resistance is associated with increased leafiness. Leaf RWC and leaf angle did not appear to be useful in predicting sensitivity to shade in any of the entries.

Combining large multi-environment trial (MET) datasets to decide which genotypes to move forward in the breeding process can be challenging, especially when dealing with negatively correlated traits. The use of a selection index has long been identified as an effective strategy in these situations. However, the method has found limited application in turfgrass breeding. The objective of this study was to use MET data for St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] breeding lines evaluated across the southern United States to compare genetic gains achieved with the additive additive genetic index (AI) versus the turf performance index (TPI) incorporating agronomic as well as consumer preference traits. The use of either selection index produced more positive genetic gains across traits than direct selection even in the presence of negative correlations. However, the higher genetic gains obtained with AI versus TPI indicate that the use of an index that weighs traits according to their importance is a better approach for selection. Moreover, under a more stringent selection intensity, none of the best lines identified with AI would have been selected with TPI emphasizing the importance of choosing selection criteria that provide a more nuanced ranking of lines. Additionally, higher heritability values and gains from selection were obtained for turfgrass quality under stress (drought and shade) than under normal conditions indicating that selection under stress environments might be more efficient. Most of the evaluated St. Augustinegrass lines outperformed the checks, further supporting the value of cross-institutional breeding collaborations. The additive selection index resulted in the highest genetic gains across traits. Genetic gains using the turf performance index were much lower. High correlations among turfgrass quality, turfgrass quality under drought, and turfgrass quality under shade were observed. Genetic gains under stress environments were higher than those under normal conditions. St. Augustinegrass breeding lines that outperformed the checks were identified. To develop a new cultivar, breeders must select the best performer among hundreds of lines. They must gather large amounts of information on how those lines perform in different locations and for a number of traits, but being able to identify which line is the best can be difficult when looking at so much data. Traditionally, turfgrass breeders have done this using an index that counted how many times a line was among the top performers. However, that index considers all traits to be equally important, which is not realistic. In this study, we tried a new index that takes into consideration the importance of the traits, and compared how much progress could be made in improving different traits when using one index versus the other. The new index was able to better differentiate the best lines and accelerate improvement of all traits. Application of this method can help breeders make better selections and ultimately result in development of better cultivars for consumers.

'FSA1602' (Reg. no. CV-294, PI 704119) hybrid St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] was developed and released by the Florida Agricultural Experiment Station, University of Florida, in 2018. FSA1602 has a distinct olive blue-green color and high levels of resistance to gray leaf spot, take-all root rot, and excellent shade tolerance and turfgrass quality (TQ). It is targeted for use in residential and commercial lawns in the southern United States. FSA1602 has coarse textured leaves similar in width to 'Floratam' and leaf lengths similar to 'SS-100' (Palmetto) but shorter than Floratam. FSA1602 stolon width is larger than Floratam or Palmetto but has a mean stolon internode length shorter than either Floratam or Palmetto. It produces a dense turfgrass with high TQ that is similar to or better than Floratam and with less winter kill than Floratam, which is the most widely used St. Augustinegrass for lawns in Florida. 'FSA1602' has a distinct olive blue-green color with coarse leaves and excellent resistance to gray leaf spot.'FSA1602' is adapted for use throughout the southern regions of gulf coast states.'FSA1602' is commercialized as 'CitraBlue' St. Augustinegrass.

'DALSA 1618' (Reg. no. CV-291, PI 702594) is a first-generation intraspecific St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] hybrid developed by Texas A & M AgriLife Research in Dallas, TX, from a cross between a drought-resistant polyploid female parent, TAES 5384 (PI 300130, GRIN National Plant Germplasm System), and a semi-dwarf shade-tolerant diploid pollen donor, 'Amerishade'. DALSA 1618 was formerly tested as 'TAES 5896-09' and 'TXSA-156'. Superior performance and quality from 2010 to 2015 in space-plant nurseries across multiple environments led to advancing DALSA 1618 to replicated trials in 10 National Turfgrass Evaluation Program (NTEP) locations across the southcentral and southeastern United States. DALSA 1618 was one of the top performers in the 2016 NTEP (2016-2020). It established faster than 'CitraBlue' and similarly to other tested commercial cultivars. DALSA 1618 exhibited high turfgrass quality in standard and ancillary trials and earlier spring greenup, which was generally better than 'Floratam'. Drought resistance of DALSA 1618 was similar to Floratam (a drought-resistant aneuploid). Tolerance to moderately dense shade was tested in Dallas, TX, from 2017 to 2020, where DALSA 1618 exhibited improved shade tolerance relative to Floratam. This array of environmental testing indicates DALSA 1618 possesses a unique combination of drought and shade tolerance that would allow its use across the southcentral and southeastern United States.

Abstract Stand establishment, early‐season seedling vigor, and mid‐season canopy closure ensure peanut growers’ timely achievement of a vigorous crop that can resist weeds, take advantage of available moisture and nutrients, and produce optimal yield. Direct measurement of these traits is prohibitively time consuming in large breeding trials and nurseries. Estimations based on visual ratings are rapid but require extensive training and experience for reliable data. Technological improvements in camera and unmanned aerial systems (UAS) has made them a practical and beneficial tool for plant breeders. This study evaluated the use of UAS for measuring plant growth‐related traits in a replicated yield trial of 16 Georgia runner‐type peanut cultivars. Flights were conducted at similar times with ground measurements and visual ratings of seedling and mid‐season plant vigor at the University of Georgia's Gibbs Research Farm in Tifton, GA, from 2019 to 2021. High correlations and similar ranks were seen between UAS‐derived and manual measurements for plant height among cultivars evaluated at mid‐season and late‐season (r2 = 0.95 and 0.75, respectively). For early‐season vigor evaluations, moderate correlations were achieved (r2 = 0.11–0.41), however, high correlations and similar results were evident comparing UAS‐derived mid‐season growth characteristics and visual vigor ratings (r2 = 0.75–0.86). Given the affordability and efficiency of data collection, UAS‐based phenotyping provides a promising and powerful tool for high throughput peanut breeding programs.

Weeds are a persistent problem on sod farms, and herbicides to control different weed species are one of the largest chemical inputs. Recent advances in unmanned aerial systems (UAS) and artificial intelligence provide opportunities for weed mapping on sod farms. This study investigates the weed type composition and area through both ground and UAS-based weed surveys and trains a convolutional neural network (CNN) for identifying and mapping weeds in sod fields using UAS-based imagery and a high-level application programming interface (API) implementation (Fastai) of the PyTorch deep learning library. The performance of the CNN was overall similar to, and in some classes (broadleaf and spurge) better than, human eyes indicated by the metric recall. In general, the CNN detected broadleaf, grass weeds, spurge, sedge, and no weeds at a precision between 0.68 and 0.87, 0.57 and 0.82, 0.68 and 0.83, 0.66 and 0.90, and 0.80 and 0.88, respectively, when using UAS images at 0.57 cm-1.28 cm pixel(-1) resolution. Recall ranges for the five classes were 0.78-0.93, 0.65-0.87, 0.82-0.93, 0.52-0.79, and 0.94-0.99. Additionally, this study demonstrates that a CNN can achieve precision and recall above 0.9 at detecting different types of weeds during turf establishment when the weeds are mature. The CNN is limited by the image resolution, and more than one model may be needed in practice to improve the overall performance of weed mapping.

In the U.S. since 2013, the sugarcane aphid is a perennial pest to all types of sorghum. Rating sugarcane aphid population density, plant damage, and other traits in sorghum requires a large amount of labor and ratings, especially damage ratings, may vary by evaluator. Thus Unmanned Aerial Systems (UAS)-based imagery may be exceedingly useful to more accurately quantify the effects on sorghum caused by sugarcane aphids. This study quantified the dynamic nature of sugarcane aphid infestations on silage sorghum varieties using UAS-based imagery data, and demonstrated the UAS-based measurements correlated to ground measurements. Two UAS platforms equipped with RGB (red, green, and blue) and multispectral cameras respectively were used to evaluate the silage sorghum variety trials during the growing seasons of 2019 and 2020. For the purpose of high throughput phenotyping in sorghum breeding, a new workflow scheme was developed including UAS image processing, raster calculation, DTM (digital terrain model) and CHM (canopy height model) generation, image extraction of sorghum plants, and tabular dataset generation from zonal statistics for further statistical analyses. Ground-based measurements included aphid sampling, aphid damage ratings, plant height, and biomass yields. The normalized difference red edge index (NDRE) and canopy cover collected by the UAS showed negative linear relationship with aphid damage ratings in both trials (R2 = 0.55-0.64). In addition to assessing spatial differences among the varieties in 2019, temporal change in both NDRE and canopy cover from the baseline sampling date in 2020 better estimated aphid damage, R2 of 0.68 and 0.79 respectively, than using the spatial difference of NDRE (R2 = 0.55) and canopy cover (R2 = 0.57) before harvest. Plant height (R2 = 0.84, Root-Mean-Square Error (RMSE) = 0.16 m) can be estimated with efficiency and precision using UAS-derived measurements during high throughput phenotyping of sorghum. Fresh yield estimates for the primary harvests were consistent in both years, but green yield estimates differed among harvests and need to be improved. Future development of UASbased high throughput phenotyping would benefit from increased temporal resolutions of growth parameters and vegetation indices throughout a growing season.

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an important pest of warm-season turfgrass species, including bermudagrass (Cynodon spp.). Bermudagrass is a popular turfgrass that is widely planted on golf courses, athletic grounds, and ornamental landscapes across the country and throughout the world. Spodoptera frugiperda infestation is often sporadic; however, when it does occur, damage can be severe. Host plant resistance against S. frugiperda can be a valuable tool for reducing or preventing the use of insecticides. Therefore, the objective of this study was to determine resistance against S. frugiperda in a few promising bermudagrasses. Fourteen experimental bermudagrass genotypes plus two control cultivars, 'Zeon' zoysiagrass (resistant control) and 'TifTuf' bermudagrass (susceptible control), were evaluated against S. frugiperda to determine host plant resistance in the laboratory. The results showed that the resistant control, 'Zeon' zoysiagrass, was more resistant than the other genotypes to S. frugiperda larvae. To determine the response of the experimental lines to S. frugiperda as compared with that of the controls, three indices were developed based on survival, development, and overall susceptibility. According to the susceptibility index, '13-T-1032', 'T-822', '11-T-510', '12-T-192', '11-T-56', '09-T-31', '11-T-483', and '13-T-1067' were the top-ranked bermudagrasses. Among these, the responses of '13-T-1032', 'T-822', '11-T-510', '11-T-56', '09-T-31', and '11-T-483' were comparable to that of 'TifTuf', and antibiosis was the underlying mechanism of resistance. Additionally, larval length, head capsule width, and weight were negatively associated with the days of pupation and adult emergence and positively associated with pupal length, thorax width, and weight. These results will help refine future breeding and with investigations of resistance against the fall armyworm.

The objective of this study was to characterize and compare mechanisms of drought avoidance and tolerance, specifically rooting characteristics, osmotic adjustment and antioxidant metabolism among different bermudagrasses. Six different bermudagrasses ('Celebration', 'Tifway', 'TifTuf', 'UGB-70', 'UGB-42' and 'UGB-208') were grown in field and growth chamber conditions and exposed to drought treatments. A range of drought performance was observed across bermudagrass genotypes with TifTuf being only the genotype to maintain a minimum acceptable turf quality rating of 6 at the end of drought treatments under field conditions. Along with TifTuf, UGB-42 and UGB-70 performed well in terms of percent green cover, normalized difference vegetation index (NDVI), leaf water status and membrane stability in both field and growth chamber conditions indicating these three genotypes had the best drought performance in the current study. Drought tolerant bermudagrasses were able to better maintain photosynthesis and transpiration after being exposed to drought. TifTuf had 15, 27 and 200 % greater osmotic adjustment (OA) compared to poor performing Celebration in 2017 and 2018 field, and grown chamber experiments, respectively. Antioxidant enzyme activities, including activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT) and glutathione reductase (GR), were mostly greater in drought-tolerant bermudagrasses. Greater antioxidant activities reduced formation of damaging H2O2 and lipid peroxidation in TifTuf, UGB-42 and UGB-70. TifTuf had 25 % greater total dry weight partitioned to roots compared to poorer performing UGB-208. Root viability was the greatest in UGB-42 and root length density (RLD) were greater in UGB-42 and UGB-70 compared to many other bermudagrasses. Results indicated better drought performances of bermudagrasses could be attributed both drought tolerance (particularly OA and antioxidant mechanisms) and desiccation avoidance (total dry weight partitioned to roots and root viability) traits.

'DALZ 1308' (Reg. no. CV-285, PI 691612) is a first-generation interspecific hybrid developed in 2004 by crossing a genotype of Zoysia minima (Colenso) Zotov and Z. matrella (L.) Merr. 'Diamond.' After field evaluations in Dallas, TX (2004-2009) and Gainesville, FL (2006-2008), DALZ 1308 was selected for advancement to the 2013 Warm-season Putting Greens National Turfgrass Evaluation Program (NTEP). DALZ 1308 was evaluated at 10 NTEP locations (2013-2018) as well as in Dallas, TX (2014-2017) and Gainesville, FL (2013-2017). DALZ 1308 exhibited a diminutive growth habit with narrower and shorter leaf blades and dwarf canopy height as compared to Diamond and L1F; shorter internode length, smaller node, and smaller internode diameter as compared to L1F; superior ball roll as compared to Diamond and L1F in Arizona, Kentucky, and Texas; resistance to tawny mole crickets; and reduced seedhead incidence and density during the growing season. As compared to Diamond and L1F, DALZ 1308 has shown to have reduced winter injury with fabric cover in Bloomington, IN. Although characteristics varied by location, DALZ 1308 exhibits good turfgrass quality, high shoot density, medium-green genetic color, and extended fall and winter color retention. Initial greenhouse experimentation under moderate shade shows that DALZ 1308 has a greater percent green cover as compared to 'Palisades', Diamond, and 'Zorro'. Overall, DALZ , 1308 is an ultradwarf zoysiagrass suitable for golf course putting greens in a wide range of environments across the United States.

Heavily shaded environments often limit the performance and persistence of hybrid bermudagrass (Cynodon dactylon × C. transvaalensis), therefore a field-based shade study was performed to determine whether different mowing heights (0.5 and 1.5 inch) or two trinexapac-ethyl (TE) growth regulator management treatments (control and 2 oz/acre) allow either ‘TifSport’ or ‘TifGrand’ hybrid bermudagrass to persist under 77% shade. Turfgrass quality (TQ), green cover, normalized difference vegetation index (NDVI), and dark-green color index (DGCI) were evaluated on the two cultivars under a shade structure in Tifton, GA, during 2010 and 2011. Neither of the cultivars maintained acceptable TQ throughout the entire year under 77% shade, although ‘TifGrand’ displayed adequate TQ at the higher mowing height (1.5 inch) and demonstrated more shade tolerance than ‘TifSport’, as indicated by TQ, green cover, and NDVI. The TE application did not enhance the turf performance of ‘TifSport’ under 77% shade when mowed at 0.5 inch, but it improved turf performance of ‘TifGrand’ at the same height. The effect of TE application was cultivar and mowing height dependent under this heavily shaded environment, which warrants future study to determine the best management practices of these cultivars as well as continued efforts to develop new, shade-tolerant bermudagrass hybrids.

Recent advances in remote sensing technology, especially in the area of Unmanned Aerial Vehicles (UAV) and Unmanned Aerial Systems (UASs) provide opportunities for turfgrass breeders to collect more comprehensive data during early stages of selection as well as in advanced trials. The goal of this study was to assess the use of UAV-based aerial imagery on replicated turfgrass field trials. Both visual (RGB) images and multispectral images were acquired with a small UAV platform on field trials of bermudagrass (Cynodon spp.) and zoysiagrass (Zoysia spp.) with plot sizes of 1.8 by 1.8 m and 0.9 by 0.9 m, respectively. Color indices and vegetation indices were calculated from the data extracted from UAV-based RGB images and multispectral images, respectively. Ground truth measurements including visual turfgrass quality, percent green cover, and normalized difference vegetation index (NDVI) were taken immediately following each UAV flight. Results from the study showed that ground-based NDVI can be predicted using UAV-based NDVI (R-2 = 0.90, RMSE = 0.03). Ground percent green cover can be predicted using both UAV-based NDVI (R-2 = 0.86, RMSE = 8.29) and visible atmospherically resistant index (VARI, R-2 = 0.87, RMSE = 7.77), warranting the use of the more affordable RGB camera to estimate ground percent green cover. Out of the top ten entries identified using ground measurements, 92% (12 out of 13 in bermudagrass) and 80% (9 out of 11 in zoysiagrass) overlapped with those using UAV-based imagery. These results suggest that UAV-based high-resolution imagery is a reliable and powerful tool for assessing turfgrass performance during variety trials.

Core Ideas Nitrogen rate had a greater impact on turfgrass quality of zoysiagrass when the grass was actively growing, but the effect of mowing height was only significant during spring green‐up. Nitrogen rate of 171 kg ha−1 was suitable for consistent turf performance in zoysiagrass and the effect of increasing N rate from 171 to 268 kg per ha was minimal. Japanese lawngrass and manilagrass can be successfully maintained at 2.5 or 5.0 cm and 0.6 or 1.2 cm, respectively, for equivalent performance during the majority of the year; however, during spring green‐up, the lower mowing height may deliver better turf performance. As new zoysiagrass (Zoysia spp.) cultivars are released, field studies on N responses and mowing heights conducted over several years under different environments are needed to determine best management practices. This study was initiated to (i) characterize a general response (color, density, turf quality) to N fertilization rate, mowing height, and their interactions among zoysiagrass cultivars; and (ii) establish appropriate mowing height and N rate recommendations for each of the cultivars studied. Four Japanese lawngrass cultivars (Z. japonica Steud.) and four manilagrass cultivars (Z. matrella L. Merr.) were evaluated in Citra, FL, for 4 yr and in Raleigh, NC, for 2 yr under three N rates (73, 171, and 268 kg ha−1 yr−1) and two mowing heights (2.5 and 5.0 cm for Japanese lawngrass; 0.6 and 1.2 cm for manilagrass). Genetic differences were evident among the zoysiagrass cultivars. Nitrogen rate had a greater impact on most of the observed characteristics when the grass was actively growing, but the effect of mowing height was only significant during spring green‐up. The medium N rate was suitable for consistent turf performance throughout the year and the effect of increasing N rate from 171 kg ha−1 to 268 kg ha−1 was minimal. Japanese lawngrass and manilagrass can be successfully maintained at 2.5 or 5.0 cm and 0.6 or 1.2 cm, respectively, for equivalent performance during the majority of the year. However, during spring green‐up, the lower mowing height may deliver better turf performance.

Drought avoidance is dictated by a collection of traits used to maintain tissue hydration levels and turgidity during water-limited conditions. These traits include deeper and more extensive rooting and the closure of stomata to limit the transpiration of water from leaves. Zoysiagrasses are a group of warm-season turfgrasses, including Zoysia japonica and Zoysia matrella, that are valued for their turfgrass quality; however, they are susceptible to drought relative to other warm-season turfgrass species. The objectives of the study were to determine 1) differences in drought avoidance among a collection of zoysiagrasses and 2) which drought avoidance traits contributed to these differences. Fifteen zoysiagrass genotypes were exposed to either drought or control conditions in a greenhouse environment. Overall performance was assessed by evaluating turfgrass quality and percentage green cover. Drought avoidance was estimated by measuring leaf hydration levels and drought avoidance traits [including stomatal conductance (g(S))]; root traits such as total root biomass, specific root length (SRL), and root length density (RLD) were measured. Compared with commercial cultivars Meyer, Palisades, or Zeon, some experimental genotypes maintained greater turfgrass quality during drought, with experimental genotype '09-TZ-54-9' having a quality rating of 7.8 after 20 days of drought compared with 5.3 in 'Zeon', 5.2 in 'Meyer', and 5.0 in 'Palisades'. A range of belowground traits such as root biomass was also found to be associated with drought avoidance, with experimental '09-TZ-53-20' having 1.03 total grams, and 2.39 total grams in '10-TZ-1254', compared with 1.14, 1.66, and 3.44 total grams in 'Meyer', 'Zeon', and 'Palisades', respectively. Significant differences in drought avoidance were found among the 15 genotypes, with both belowground rooting traits and aboveground factors affecting transpiration influencing plant performance.

Characterization of rooting capacity in the greenhouse is a routine screening procedure for assessing a plant's ability to cope with drought stress. However, an association between rooting capacity in the greenhouse and turf performance in the field during drought is not always found. The objectives of the study were (i) to classify zoysiagrass (Zoysia spp.) rooting characteristics under well‐watered conditions in the greenhouse, (ii) to compare zoysiagrass performance under drought conditions in the field, and (iii) to relate the results from the greenhouse to the drought responses in the field. The greenhouse study included 17 zoysiagrass genotypes grown in clear acrylic tubes. Root morphological traits and dry weight at different depths (0–30, 30–60, 60–90, and 90–120 cm) were evaluated. Visual responses of zoysiagrass to field dry down were evaluated, and total turf performance index (TTPI) was used to rank the genotypes. Genotypes with higher root length density and root dry weight at 30 to 120 cm, deeper maximum root depth, and lower fraction of surface root length in the greenhouse study were better performers (high TTPI) in the field dry down study and included ‘UF 182’, ‘Emerald’, ‘JaMur’, and ‘Palisades’. The correlation between the greenhouse study and the field dry down study suggests that improvement of drought resistance may be achieved by screening for root traits in the greenhouse.

Warm season turf taxa of centipedegrass [Eremochloa ophiuroides (Munro) Hack], bermudagrass [Cynodon L.C. Rich. spp.], St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and zoysiagrass [Zoysia Willd. spp.] were evaluated for tolerance to adult twolined spittlebug (Prosapia bicincta Say) feeding in choice and no-choice experiments, and for their ability to support nymphal development (antibiosis potential). Among 133 selections evaluated, few showed evidence of potential antibiosis and/or improved tolerance over commercially available cultivars. Most of the centipedegrass taxa evaluated were susceptible to the spittlebug. However, some potential antibiosis among Chinese centipedegrass taxa was identified, and there was a gradient in the ability to tolerate spittlebug feeding. Among centipedegrasses, TC 358 and TC 362 showed moderate tolerance and recovery in no-choice and choice trials. The most tolerant bermudagrasses in no-choice trials were 00-23, 03-14, and 03-15. Centipedegrasses overall were the best hosts for nymph development, but TC 379, TC 422 and E. ciliaris did not support nymph development, and TC 341 and TC 399 showed very low numbers of nymphs. The bermudagrasses 00 -23 and 00 -28 and the St. Augustinegrasses T638 and Mercedes failed to support nymph development.

Warm-season grasses are characterized by the C4 photosynthetic pathway. This pathway occurs in 18 families of flowering plants, and 61% of the species belong to the grass family. This chapter discusses the major warm-season grass species used for turf. Bermudagrass is one of the most widely used turfgrasses on athletic fields, golf courses, lawns, and various other recreational areas around the world. Zoysiagrass cultivars are valued for their adaptation to the northern transition zone and for their low fertility requirements. Seashore paspalum is valued for its salt tolerance and maintenance of green color under cool temperatures. Centipedegrass has one of the lowest fertility requirements for maintaining desirable turf and it does not scalp. St. Augustinegrass is best adapted to sandy, high-pH soils and is the predominant species used for home lawns in the Gulf Coast regions of the United States. Carpetgrass and bahiagrass are mainly used for very low input turf in the south.