Turf Performance Research Articles

Maximizing genetic gains across agronomic and consumer preference traits in St. Augustinegrass breeding

AbstractCombining 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.

Plant health effects of fungicides alone and in combination with plant growth regulator on improving summer turf performance in annual bluegrass

Plant health effects of fungicides alone and in combination with plant growth regulator on improving summer turf performance in annual bluegrass

Brown patch severity of five tall fescue cultivars as influenced by summer nitrogen rates

Turf-type tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.: TTTF] is a predominant turfgrass species for lawns throughout cool-humid regions, yet brown patch (caused by Rhizoctonia and Rhizoctonia-like species) can cause severe damage during the summer months. Hypothesized strategies to help minimize brown patch severity and decrease fungicide use includes establishing TTTFs with a high level of host resistance and minimizing summer nitrogen (N) applications. A two-year field study was conducted in West Lafayette, IN to determine the influence of late-spring and summer applied N at two application rates among five TTTF cultivars. Urea-N was applied monthly at two rates from April to July, totaling to 73.5 and 245.0 kg N ha−1. Turf performance was determined using visual ratings for turf quality, relative canopy greenness, disease severity (0–100%), and seasonal brown patch as calculated by area under the disease progress curve (AUDPC). Brown patch was generally not affected by N-rate for any cultivar in either study year. While none of the TTTF cultivars had complete brown patch resistance, cultivar differences were observed, with disease severity ranging from 9.8 to 39.0% and 20.0–51.9% in 2021 and 2022, respectively. Selecting a brown patch resistant cultivar reduced seasonal brown patch severity by 61% across study years compared to the most susceptible cultivars. This study demonstrates that summer N applications to TTTF lawns should not be completely avoided to reduce brown patch as previously suggested and emphasizes the importance of host resistance for disease management.

Synthetic turf finite element model development and validation

Assessment of synthetic turf performance has been undertaken using a variety of experimental methods but is limited in understanding the complex physics of cleat-turf interaction. Computational models could provide insight, but there is currently no validated model of synthetic turf available. The scope of this study was to develop a Finite Element (FE) model of synthetic turf using a hierarchical approach and validate the model using independent test data. A physical third-generation synthetic turf comprising slit-film fibers with sand and rubber crumb infill was constructed. Experiments were conducted using a direct impact (Clegg) device and an artificial cleat-form. Material characterization tests were performed on the individual turf components, integrated into constitutive models, and a full turf FE model was constructed. The carpet was modeled with shell elements while the granular infill was modeled using smoothed-particle hydrodynamics (SPH) elements. A method to simulate the physical pre-conditioning performed on the experimental turf was developed. Both unconditioned and pre-conditioned turfs were assessed using Clegg tests. The re-created Clegg tests on the turf model demonstrated good agreement with the physical tests, with higher acceleration for the pre-conditioned turf. The turf model was validated using experiments with a turf test apparatus including dynamic translation and rotation of a cleat-form. The model predicted results in good agreement with the experiments (average CORA rating of 0.863) on pre-conditioned turf. The resulting model and methods can be expanded to synthetic turf of different constituent materials, to investigate their effects on cleat-surface interaction, optimizing performance, and reducing injury risk.

Using Sewage Sludge as Alternative Fertilizer: Effects on Turf Performance of Perennial Ryegrass

Two years of research were carried out to evaluate the effects of various sewage sludge and nitrogen doses on the turf performance of perennial ryegrass (Lolium perenne L.) under Mediterranean-type climatic conditions. Four nitrogen sources (NS) [NS1: ammonium nitrate (26%), NS2: Bursa City’s wastewater treatment plant’s waste, NS3: biogas production plant reactor waste, and NS4: food processing and canning factory’s sludge waste] were used in the research. Four different nitrogen doses (0.0, 2.0, 4.0, and 6.0 g m−2) were applied. The sewage sludges were analyzed before the start of the research. It was determined that the heavy metal concentrations were below the limit values, and the plant nutrient content was high. Turfgrass color and quality observations were taken in the study, and turfgrass clipping yield was determined. The 4.0 g m−2 nitrogen dose provided acceptable turf color and quality values among the sewage sludges. NS4 showed the best turf performance among the sewage sludges. Despite increased turf color and quality values, sewage sludge produced a low clipping yield. Food processing and canning factories’ sewage sludges can be alternatives to a nitrogen source.

Transportation sand leakage and turf performance of sand-based removable modular turf as affected by the combined action of coir fiber and polyacrylamide

Removable modular turf with a sand-based rootzone is a solution for high-end stadiums which can organize various events on the turf. However, the low stability of sand leads to serious sand leakage during the transportation of modular turf, which reduces the evenness and safety of the turf. Previous studies have shown that adding coir fibers (CF) and polyacrylamide (PAM) will improve soil stability. In this study, we evaluated the combined effects of CF and different amounts of PAM on soil properties, turfgrass growth, shear strength, and sand leakage during simulated transport vibrations in a sand-based modular turf planted with tall fescue ( Festuca elata Keng ex E. Alexeev). Each treatment comprised a mixture of 0.4% (weight material/weight soil) CF and six concentrations of PAM (0%, 0.025%, 0.050%, 0.075%, 0.100%, 0.125%, w/w) in the sand-based rootzone, with no addition of CF or PAM as the control. The results show that, in the sand-based rootzone, CF could improve tall fescue growth, shear strength, and resistance to sand leakage owing to transport vibration due to the physical properties of the coir fiber. However, the combined effect of CF and 0.100% PAM was better for tall fescue growth, shear strength, and resistance to sand leakage. However, owing to the lubricating effect of PAM, adding a low (≤0.025%) or a high rate (≥0.125%) amount of PAM would reduce the effect of CF and PAM. Therefore, the combined effect of CF + 0.100% PAM in this study had the best effect on the turf module and can be used as an application scheme for the removable modular turf.

Advanced Turf-type Bermudagrass Experimental Genotypes Show Marked Variation in Drought Response

Bermudagrass (Cynodon sp.) is one of the most commonly used warm-season turfgrasses in the southern areas and transition zone of the United States. Due to the increasing demand for water resources and periodic drought, it is important to improve the drought resistance of bermudagrass for water savings and persistence under drought stress. This study was conducted to determine whether experimental bermudagrass genotypes have improved drought resistance compared with the standard cultivars Tifway and Riley’s Super Sport (Celebration®) at Stillwater, OK. The trials were designed as randomized complete blocks with four replications in Expt. I and three replications in Expt. II. In each experiment, genotypes were subjected to progressive acute drought conditions using polyethylene waterproof tarps to exclude precipitation over a period of at least 72 d. Bermudagrass entries were evaluated for turfgrass quality, leaf firing, normalized difference vegetation index, and live green cover at least once each week during the dry-down. Substantial drought response variations were found in this study, and all parameters were positively and highly correlated. A turf performance index (TPI) was assembled based on the number of times an entry ranked in the top statistical group across all testing parameters on each date. ‘DT-1’ (TifTuf®) and OSU1221 had the top TPI in both experiments. Most of bermudagrass experimental genotypes had equal or greater TPI than the standard Tifway, showing improved drought resistance through breeding effects. The identification of superior drought resistance experimental genotypes provided useful information to breeders on cultivar release.

Impacts of seeding rates of different <em>Lolium</em> species on winter overseeding of seashore paspalum in Mediterranean regions: turf quality and suitability for football pitches

Overseeding is an essential management practice for turf cultivation in winter. Warm-season turfgrasses must be overseeded with cool-season turfgrass in the fall to provide green colour and maintain suitable playing surfaces by preventing wear on the dormant warm-season turfgrass throughout the winter months. The cool-season turfgrass species selected for overseeding affect the success or failure of the process in different ways via interaction with environmental conditions. A 2-year research study was conducted at the experimental areas of the Field Crops Department, Agriculture Faculty, Ege University in Izmir/Turkey during 2016-2018. The objectives of the study were to evaluate the overseeding performances of seashore paspalum cv. Sea Spray with different ryegrass (Lolium) species (diploid perennial ryegrass cv. Sun, tetraploid perennial ryegrass cv. Tetragreen, annual ryegrass cv. Axcella, intermediate ryegrass cv. TransAm), and determine the most suitable seeding rates (50, 75, 100 g m-2) for the Mediterranean climate. In the study, the evaluation of turf performance traits such as colour, visual turf quality, cover, fall and spring transition was conducted in both years. Additionally, some football playing quality traits, including ball rebound, force reduction, and vertical deformation were measured during the research periods. According to the results, tetraploid perennial ryegrass cv. Tetragreen and diploid perennial ryegrass cv. Sun generally performed better than the others. Concerning the overseeding rate, 75 or 100 g m-2 applications are recommended as the most suitable for obtaining good turfgrass quality and football playability.

Foliar Application of Carnosine and Chitosan Improving Drought Tolerance in Bermudagrass

Drought stress is one of the crucial factors affecting plant growth and development in turfgrass species, especially during the summer season. Exogenous plant growth regulators are an effective and convenient approach to mitigating the adverse effects of drought stress on plant growth. The objectives of this study were to reveal the effects of exogenous carnosine or chitosan on turf performance and physiological indexes in bermudagrass (Cynodon transvaalensis × C. dactylon) in response to drought stress. Bermudagrass was foliar sprayed with carnosine or chitosan, and dose-dependent effects on turf quality were observed under drought stress. Under drought stress, foliar application of either carnosine (0.03%) or chitosan (10 mg L−1) significantly increased turf quality, chlorophyll content, leaf relative water content, and decreased electrolyte leakage, malonaldehyde, and hydrogen peroxide content in comparison with untreated control in bermudagrass. Moreover, exogenous carnosine treatment significantly enhanced the activities of both catalase and peroxidase, but chitosan application only increased catalase activity. The results of this experiment were beneficial to the development of new plant growth regulators and would provide helpful insights for turf management under drought-stressed conditions.

Development of winter hardy, fine‐leaf zoysiagrass hybrids for the upper transition zone

AbstractA 10‐yr, four‐phase collaborative effort among three universities was conducted to develop new hybrid zoysiagrasses (Zoysia spp. Willd.) with improved turf quality, winter hardiness, and pest resistance in comparison to commercial zoysiagrass cultivars, especially ‘Meyer’ (Z. japonica Steud.). In Phase 1, breeding efforts produced 2,858 new progeny that were evaluated for 2 yr across three sites. In Phase 2, only 60 (2%) of 2,858 progeny were selected for advancement to 10 replicated multiyear field trials (Phase 3). Phase 3 revealed 10 promising progeny (assigned DALZ numbers) that required further intensive field and laboratory testing in Phase 4. Phase 4 revealed differences in establishment rate, and DALZ 1701, 1702, 1707, and 1810 had moderate‐to‐good turf performance across seven sites, whereas DALZ 1808 had similar or slightly lower performance. Meyer consistently performed poorly, and ‘Innovation’, a recently released hybrid cultivar, had poor‐to‐moderate performance in comparison to the experimental genotypes, which illustrates the improvements achieved in zoysiagrass breeding in the last 10 yr. Freeze tolerance (LT50, lethal temperature killing 50% of the plants) ranged from −9.8 °C (Diamond) to −14.1 °C (DALZ 1812) with a mean of −12.5 °C. Evidence of large patch [Rhizoctonia solani Kühn, anastomosis Group (AG) 2‐2 LP] in the top 10 DALZ genotypes was 15 to 40% lower than Meyer on several dates. Results indicate that there are multiple genotypes for potential release in the future with improved turf color, winter hardiness, freeze tolerance, large patch resistance, and finer leaf texture suitable for USDA plant hardiness zones ranging between 5b and 8a.

Familiarity and Use of Biostimulants by the Georgia Golf Industry: Information from a Survey of Golf Course Superintendents

Golf course superintendents are often under pressure to maintain high-quality turf. Such demand entails use of inputs, which can include biostimulants that are often marketed as a way of combating plant stress and improving turf quality. However, the extent of their use by superintendents and their level of efficacy are not well understood. This survey study was designed to better describe biostimulant use by the golf industry and to gain insights on the research needs of superintendents to address them effectively. A survey instrument was developed using online software and included a total of 13 questions relating to general familiarity with biostimulants and specific familiarity with five biological products. The instrument was disseminated electronically via the online survey tool to attendees (N = 80) during the annual conference of the Georgia Golf Environmental Summit in 2022. The respondents were from 62 golf courses, geographically representing the entire state of Georgia. The response rate was 62.5%. The majority of the respondents (86%) were familiar with biostimulants. The main reason for using biostimulants was predominantly agronomic, indicating a focus on turf performance and aesthetics. Of the respondents who used biostimulants, the overwhelming majority (93%) use humic acids and plant growth hormone-containing biostimulants. Respondents also indicated that research in microbial products would be the most relevant to the industry. This may be explained by the challenges in using such products (shelf life and microbial survival in soil). In conclusion, the survey indicated that Georgia golf course superintendents have high a level of familiarity with biostimulants. The survey yielded useful results to help formulate future research objectives to better serve the Georgia golf course industry.

Differential Regulation of Amino Acids and Nitrogen for Drought Tolerance and Poststress Recovery in Creeping Bentgrass

Effects of amino acids and nitrogen on plant regrowth or recovery from drought stress remain largely unknown. The objectives of this study were to examine how gamma-aminobutyric acid (GABA) or proline, alone and in combination, or inorganic nitrogen [ammonium nitrate (NN)] may differentially affect turf performance during drought stress and rewatering, and to determine which specific endogenous amino acids regulated by GABA, proline, or NN priming were associated with plant tolerance to drought stress and postdrought recuperation in cool-season grass species. Creeping bentgrass (Agrostis stolonifera cv. Penncross) planted in porous ceramic fritted clay medium were exposed to well-watered conditions or drought stress by withholding irrigation for 21 days in growth chambers. Plants were treated with water (untreated control), GABA, or proline alone and in combination, or NN through foliar spray before drought stress and every 7 days during the 21-day stress period. For postdrought recovery, at 21 days of drought treatment, plants were rewatered for 14 days to return soil water content to prestress levels. Plants treated with GABA or proline alone or in combination maintained higher turf quality (TQ), dark green color index (DGCI), and stolon length by 21 days of drought stress, whereas proline-treated plants also maintained higher leaf relative water content (RWC) during drought as well as longer stolon length during rewatering. Plants treated with NN maintained higher TQ and leaf RWC during drought and had improved percent canopy cover, DGCI, and stolon length during postdrought rewatering. Accumulation of endogenous amino acids under drought stress, including proline and alanine, for proline-treated creeping bentgrass may have contributed to the enhancement of drought tolerance and postdrought regrowth. Nitrogen-enhanced accumulation of GABA, proline, and glutamic acid may have played a role in active amino acid assimilation and subsequent postdrought regrowth. Results from this study indicate that GABA or proline were mainly effective in promoting the tolerance of creeping bentgrass to drought stress while inorganic NN was effective in promoting rapid postdrought recovery and regrowth potential through the activation of amino acid metabolism. Endogenous amino acids, including GABA, proline, alanine, and glutamic acid, may be used as biomarkers to select for drought-tolerant plants and biostimulant components for improvement of drought stress tolerance and poststress recovery in cool-season turfgrass species.

Morphophysiological Responses of Two Cool-Season Turfgrasses with Different Shade Tolerances

Understanding the differences in cool-season turfgrass responses to shade is critical for future turfgrass management and breeding for improved shade tolerance. The purpose of this study was to evaluate the shade-tolerance mechanisms of two cool-season turfgrass species in terms of turf performance, growth, and physiological characteristics. Two turfgrass species, namely, ’SupraNova’ (Poa. supina Schrad.) and ‘Lark’ (Lolium perenne L.), were subjected to 0 (CK, unshaded), 35% (LS), 70% (MS), and 92% (HS) shade, respectively. Compared with ‘Lark’, ‘SupraNova’ showed better turf quality (TQ) and turf color intensity (TCI) under shade. The total length and surface area of the roots of ‘Lark’ gradually decreased as the shade increased, while those of ‘SupraNova’ increased and then decreased with increasing shade. The chlorophyll fluorescence photochemical quenching coefficient (qP), electron transport rate (ETR), and maximum quantum yield of primary photosystem II (PSII) photochemistry (Fv/Fm) decreased significantly under HS; however, these decreases were more significant in ‘Lark’ than in ‘SupraNova’. The leaf reflectance of the two turfgrasses under shade was lower than that under CK, but the leaf reflectance of ‘Lark’ was higher than that of ‘SupraNova’ in the visible light band. The normalized difference vegetation index (NDVI) of the two grasses first decreased and then increased. The NDVI of ‘Lark’ under shade was slightly higher than that under CK. ‘SupraNova’ showed strong tolerance on the basis of malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide anion (O2·−), and ascorbic acid (AsA) contents and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity. The MDA, H2O2, O2·−, and AsA contents and SOD, POD, and CAT activity (which represent indicators) changed the most under MS. Taken together, the results indicated that the adaptability of ‘SupraNova’ to shade was better than that of ‘Lark’.

Multienvironment evaluation of St. Augustinegrass breeding lines for turf performance via a mixed‐models approach

AbstractSt. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] is a turfgrass extensively used in managed landscapes in Florida and throughout the southeastern United States. To develop cultivars with broad adaptation, it is necessary to understand the effect of genotype × environment interactions. The objective of this study was to estimate genetic parameters in St. Augustinegrass for coverage, turf quality (TQ), and turf color (TC) in a multienvironment trial across five locations in Florida (Arcadia, Hague, Citra, Cocoa Beach, and Jay) evaluated over 5 yr (2011–2016). The experiment consisted of 26 advanced breeding lines, and four cultivars: ‘Floraverde’, ‘SS‐100’ (Palmetto®), ‘NUF‐76’ (Captiva®), and ‘Floratam’. Trials were arranged as randomized complete block designs with three replications. Linear mixed models with repeated measures were implemented in ASReml‐R. Significant differences were observed among genotypes. The estimates of genotype‐mean broad‐sense heritabilities ranged from 0.37 to 0.96 for coverage, 0.00 to 0.37 for TC, and 0.27 to 0.93 for TQ. Genotypic correlations ranged from 0.05 to 0.90 for coverage, 0.48 to 0.69 for TC, and 0.35 to 0.83 for TQ, indicating stable genotypic performance for TQ and TC between locations. For coverage, most genotypes clustered together, whereas greater genotypic variability was observed for TQ and TC. Genotypes ‘04‐4‐1‐4‐6’ and ‘FSA1602’ showed the best overall performance across the different traits analyzed for most locations and both genotypes are recommended for further use in future crosses in the breeding program. FSA1602 was recently released as FSA1602 and is being commercialized under the trademark CitraBlue®.

Turf performance and physiological responses of native Poa species to summer stress in Northeast China.

Rapid rise in temperature in summer causes severe injury to cool-season turfgrass of both native species and introduced ones in Heilongjiang of Northeast China. The objectives of this study were to compare physiological responses to seasonal heat stresses and turf performances between native and introduced commercial Poa accessions. Three Chinese native Poa species (i.e., P. pratensis, P. sibirica and P. sphondylodes) and three USA Kentucky bluegrass cultivars (ie. ‘Midnight’, ‘Moonlight’ and ‘BlueChip’) were evaluated under field conditions in 2017 and 2018. All accessions showed unique characteristics and considerable seasonal differences in response to temperatures. However, performances over all accessions were largely similar in early spring and autumn. In summer, native P. pratensis performed similar to ‘Midnight’, ‘Moonlight’ or ‘BlueChip’, with respect to such traits or parameters as quality, coverage, color intensity, growth rate, osmolytes, ROS and anti-oxidant production. Native P. pratensis could be used as a new turf resource for further improvement and application under the specific climatic conditions in Heilongjiang; native P. sphondylodes may be used in repairing damaged environments or for alternative seasonal greenness.

Performance of five typical warm‐season turfgrasses and their influence on soil bacterial community under a simulated tropical coral island environment

AbstractVegetation is a key to improving and protecting a new tropical coral island terrestrial ecosystem. Because of their superior ability in adapting poor soil structure and fertility, conserving soil and water and improving the living environment, warm‐season turfgrass are considered as important pioneer plants and frequently applied in vegetation construction on tropical coral islands. However, few studies had evaluated the growth of these turfgrass and how these turfgrass influence the soil microbial communities on tropical coral islands. In this study, we conducted a greenhouse experiment and assessed the performance, soil properties and rhizosphere bacterial communities of five typical warm‐season turfgrasses species (i.e., Paspalum vaginatium, Paspalum notatum, Cynodon dactylon, Zoysia tenuifolia, and Stenotaphrum helferi) grown on tropical coral sand. Results showed that C. dactylon was superior in the adaptability and turf performance among the studied species, with a turf establishment time of 34 days and a turf quality score of 6.83. Richness of bacterial species and nitrifying bacteria in its rhizosphere soil planted with C. dactylon were also much higher than with other species. The speed of turf establishment was positively correlated with rhizosphere soil bacterial species richness. Our findings indicated that C. dactylon could be a potentially suitable candidate species for vegetation restoration and soil bacterial community conservation on tropical coral islands.

Humic acids‐based biostimulants impact on root viability and hormone metabolism in creeping bentgrass putting greens

AbstractCreeping bentgrass putting greens experience quality decline during summer due to heat and drought stress in U.S. transition zone and other areas with similar climate. Plant biostimulants have been used to improve turfgrass tolerance to abiotic stress. This study was designed to investigate the effect and modes of action of humic acid (HA) based biostimulants on turf quality, root viability, and hormone metabolism of creeping bentgrass during summer stress. The two humic acid formulations – solid powder and liquid, were characterized and applied at two rates of each formulation to a creeping bentgrass putting green from May through August in this study. Auxin indole‐3‐butyric acid (IBA) served as the positive control. Foliar application of either solid or liquid HA at 0.2% and 0.3% biweekly improved turf quality, photochemical efficiency and chlorophyll content at certain sampling dates. The HA treatments also increased leaf growth hormone cytokinin zeatin riboside (ZR) on July 25 and August 22 and auxin indole‐3‐acetic acid (IAA) on August 22. The HA treatments improved root length, surface area (SA), root volume, biomass, and viability. Solid HA (HA‐S) at 0.2%, 0.3% solution, liquid HA (HA‐L) at 0.2%, and 0.3% increased root viability by 91.8%, 122.4%, 57.1%, and 71.4%, respectively, when compared to the control. This study suggests foliar application of humic acid‐based biostimulants may be considered as an effective tool to improve turf performance in creeping bentgrass putting greens during summer months.

Selection of New Zoysiagrass Genotypes for Golf Course Fairways, Greens, and Tees in the Upper Transition Zone

A set of 70 experimental zoysiagrass genotypes along with three standards, ‘Meyer,' ‘Innovation,' and ‘KSUZ 1201,' were evaluated for turf performance in the northern transition zone. The genotypes were previously selected from a set of 935 progeny that resulted from pairwise crossings of cold-hardy zoysiagrass parents with fine-textured, under-utilized zoysiagrasses. All 70 progeny survived the winter of 2019–2020 and thus were evaluated based on their turf performance. The preference of selection was based first upon spring green up ratings, followed by leaf texture (finer preferred), vigor, turf quality, and wilt during dry down. A total of 20 best progeny were selected and harvested for propagation on October 12, 2020. Only one geno­type, ‘6844-31’ had a texture rating of 8.0 (1 to 9 scale; 9 = finest texture) and four other genotypes had texture ratings higher than 7.0 among the selected 20 best progeny. The progeny will be established in larger replicated plots at several locations including Kansas State University Olathe Horticulture Center, Olathe, KS, starting in the summer of 2021

Performance and playability of experimental low-input coarse-textured zoysiagrass in multiple climates

A 3-year experiment was conducted to evaluate the performance and playability of 24 coarse-textured zoysiagrass (Zoysia spp. Willd.) experimental genotypes in comparison to five commercially available cultivars maintained as a low-maintenance turf across multiple climates (Indiana, North Carolina, Georgia, Arizona, and California). Following establishment in 2018, plots were maintained under low-maintenance regimes and evaluated for quality, density, uniformity, color, winterkill damage, drought resistance, and golf ball lie in 2019 and 2020. A turf performance index (TPI) was calculated for each treatment at each site, which represented the number of times the treatment occurred in the top statistical group. The unique climate for each site led to differences in TPI scores. For instance, the arid climates of Arizona and California resulted in distinct differences in performance among treatments compared to the other sites. However, consistencies in performance across sites were also observed. For example, the 2018−2019 winter resulted in winterkill differences among entries in both Indiana and North Carolina, which led to some similarities in TPI. Furthermore, the southern humid climates of North Carolina and Georgia produced consistencies in overall TPI. Under the minimal inputs and the hot-humid or arid climates evaluated in this study, all of the check cultivars were some of the poorest performing treatments, which clearly illustrates there is a need for breeding programs to develop zoysiagrass genotypes for these climates. However, experimental lines that exhibited excellent persistence under these conditions were identified indicating the genetic potential for wider adaptation to lower input environments exists within the species.

The Optimized N, P, and K Fertilization for Bermudagrass Integrated Turf Performance during the Establishment and Its Importance for the Sustainable Management of Urban Green Spaces

Bermudagrass (Cynodon dactylon (L.) Pers) turf is the most widely used turfgrass in urban landscapes. Large amounts of fertilizer are usually applied for maximum turf performance, while relatively little attention has been paid to efficient nutrient management of bermudagrass turf. The design opted for was a 3-factor and 5-level Central Composite Rotatable Design (CCRD) consisting of 24 experimental runs in the greenhouse with response surface methodology (RSM) and simulated regression modeling. The experiment covered in this study was carried out at Sichuan Agricultural University with the objectives of understanding the interactive effects of nitrogen, (N), phosphorus (P), and potassium (K) fertilization on the bermudagrass integrated turf performance (ITP) and optimizing the amount of N, P, and K required for optimum turf performance during establishment. The qualitative and quantitative relationships between bermudagrass and fertilization significantly affected the ITP. The N, P, and K Fertilization significantly influenced the percent grass cover, turf height, shoot dry weight, root dry weight, and total chlorophyll content. Fertilization with N and P significantly enhanced the tiller length, turf density, color, and total protein levels. Root length was augmented with the application of P and K. We found that 3-D surface plots indicated significant interactive effects of NP, NK, and PK on the ITP. A simulation optimization and frequency analysis indicated that the optimal combined amounts of these nutrients were N: 26.0–27.6 g m−2, P: 24.2–26.4 g m−2, and K: 3.1–5.0 g m−2 during the establishment phase. The results suggest that optimized fertilization is key to sustainable nutrient management of bermudagrass integrated turf performance.