Turfgrass Species Research Articles

Establishment of Kentucky bluegrass and tall fescue seeded after herbicide application

AbstractWeed control before seeding is often required for successful turfgrass establishment, since weed interference prior to turfgrass tillering causes a reduction of cover and density. However, herbicides differ widely in the delay required after herbicide application before seeding can occur without injury to seedlings. The objective of this research was to determine the influence of three selective postemergence grass, broadleaf, and sedge herbicides on the cover and density of Kentucky bluegrass (Poa pratensis L.) and tall fescue (Schedonorus arundinaceus Schreb.) seeded 0, 3, 7 or 14 d after herbicide application. Herbicide treatments included: an untreated control, 2,4‐D + 2‐(2‐methyl‐4‐chlorophenoxy)propionic acid (MCPP) + dicamba (1.64 lb acid equivalent acre–1), quinclorac (0.75 lb a.i. acre–1), halosulfuron‐methyl (0.06 lb a.i. acre–1), and dithiopyr (0.50 lb a.i. acre–1), which was included for comparison. Seeding between 0 to 14 d after an application of 2,4‐D + MCPP + dicamba or quinclorac had little or no effect on Kentucky bluegrass or tall fescue cover in Manhattan, KS, and Wooster, OH. Halosulfuron‐methyl reduced the cover of both turfgrass species when seeded 0 or 7 d after application. This research demonstrates that turfgrass managers who unknowingly seed into areas treated with 2,4‐D + MCPP + dicamba or quinclorac within 0 to 14 d after treatment are likely to observe successful establishment of Kentucky bluegrass or tall fescue under the conditions evaluated in these experiments.

Early Nutrient Diagnosis of Kentucky Bluegrass Combining Machine Learning and Compositional Methods

Kentucky bluegrass (Poa pratensis L.) is the most common perennial turfgrass species grown on playgrounds, municipal and residential lawn areas, and golf tees, fairways and roughs. Fertilization is the most efficient way to improve and maintain turfgrass aesthetic quality. Tissue diagnosis can guide fertilization, but tissue concentration ranges are biased by not taking into consideration nutrient inter-relationships, carryover effects and other key features. The centered log-ratio transformation reflects nutrient interactions in plants and avoids statistical biases. Machine learning (ML) models relate the target variable to the key features ex ante, and can predict future events from prior knowledge. The objective of his study was to predict turfgrass quality from key features and rank nutrients in the order of their limitations. The experimental setup comprised four N, three P, and four K rates applied on permanent plots during three consecutive years. Soils were a loam and an USGA sand. Eleven elements (N, S, P, K, Ca, Mg, B, Cu, Zn, Mn, Fe) were quantified in clippings collected during spring, summer and autumn every year. Turfgrass quality was categorized as target variable by color rating. Concentrations were centered log-ratioed (clr) partitioned into four quadrants in the confusion matrix generated by the xgboost ML model. The area under curve (AUC) and model accuracy were high to predict turfgrass color from the nutrient analyses of clippings collected in the preceding season, facilitating the seasonal adjustment of the fertilization regime to sustain high turfgrass quality. We provide a computational example to run the ML model and rank nutrients in the order of their limitations.

Duman Solüsyonlarına Maruz Kalan Bazı Çim Türlerinin Çimlenme ve Fide Büyümesi

This study aimed to investigate the effect of priming with plant-derived smoke solutions (SS) on the germination, seedling growth and chemical content of three turfgrass species (Lolium perenne, Festuca arundinacea, Poa pratensis). SS was applied at six concentrations (0, 0.5, 1, 5, 10 and 20%) in petri and pot conditions. In petri condition, SS did not stimulate the germination speed, and the highest concentrations (20%) led to lower values than control. In the pot conditions, seedling growth and chemical content were significantly stimulated by the SS. The effect of the SS varied depending on the species and concentrations. Shoot and root length in grass species were improved by the SS, except in P. pratensis for shoot length. Compared to control, higher shoot dry weight in F. arundinacea (1%) and higher root dry weight in L. perenne (5%) and F. arundinacea (0.5%) were determined at certain concentrations. These results showed that priming with SS at appropriate concentrations may lead to healthy and vigorous seedlings. When seedling vigor and visuality are evaluated together, it has been determined that priming with low concentrations of SS such as 0.5 and 1% can produce vigorous seedling.

Functional Characterization of the Pheophytinase Gene, ZjPPH, From Zoysia japonica in Regulating Chlorophyll Degradation and Photosynthesis.

Pheophytinase (PPH), the phytol hydrolase, plays important roles in chlorophyll degradation. Nevertheless, little attention has been paid to the PPHs in warm-season grass species; neither its detailed function in photosynthesis has been systematically explored to date. In this study, we isolated ZjPPH from Zoysia japonica, an excellent warm-season turfgrass species. Quantitative real-time PCR analysis and promoter activity characterization revealed that the expression of ZjPPH could be induced by senescence, ABA, and dark induction. Subcellular localization observation proved that ZjPPH was localized in the chloroplasts. Overexpression of ZjPPH accelerated the chlorophyll degradation and rescued the stay-green phenotype of the Arabidopsis pph mutant. Moreover, ZjPPH promoted senescence with the accumulation of ABA and soluble sugar contents, as well as the increased transcriptional level of SAG12 and SAG14. Transmission electron microscopy investigation revealed that ZjPPH caused the decomposition of chloroplasts ultrastructure in stable transformed Arabidopsis. Furthermore, chlorophyll a fluorescence transient measurement analysis suggested that ZjPPH suppressed photosynthesis efficiency by mainly suppressing both photosystem II (PSII) and photosystem I (PSI). In conclusion, ZjPPH plays an important role in chlorophyll degradation and senescence. It could be a valuable target for genetic editing to cultivate new germplasms with stay-green performance and improved photosynthetic efficiency.

Integrated physiological and transcriptomic analyses of two warm- and cool-season turfgrass species in response to heat stress

Warm- and cool-season turfgrasses were originated from different locations with contrasting heat tolerance. The molecular mechanisms of heat tolerance have not been extensively studied in turfgrass species. In this study, transcriptomic analysis showed that bermudagrass was more tolerant to heat stress as evidenced by lower contents of H2O2, proline and glutathione than those in tall fescue after heat treatment. RNA sequencing analysis revealed that 32.7% and 17.7% more genes were changed in tall fescue than in bermudagrass after 2 and 12h heat treatment, respectively. GO terms of redox were enriched in bermudagrass whereas metabolite transportation ones were over-represented in tall fescue after 2h treatment. Ubiquitin dependent degradation pathways were commonly regulated in both grass species. CdF-box and FaF-box transgenic Arabidopsis exhibited improved tolerance to heat stress. Regulatory elements analysis revealed that four ABA-responsive elements present in CdF-box promoter, indicating CdF-box could be potentially regulated by ABRE binding factors (ABFs). All these findings provide evidences for understanding heat stress response in warm- and cool-season grass species.

CdWRKY2-mediated sucrose biosynthesis and CBF-signalling pathways coordinately contribute to cold tolerance in bermudagrass.

SummaryBermudagrass (Cynodon dactylon) is one of the most widely cultivated warm‐season turfgrass species around the world. Cold stress has been a key environmental factor that adversely affects the growth, development, and geographical distribution of bermudagrass; however, the underlying mechanism of bermudagrass responsive to cold stress remains largely unexplored. Here, we identified a cold‐induced WRKY transcription factor CdWRKY2 from bermudagrass and demonstrated its function in cold stress response. Overexpression of CdWRKY2 enhanced cold tolerance in transgenic Arabidopsis and bermudagrass hairy roots, while knocking down CdWRKY2 expression via virus‐induced gene silencing increased cold susceptibility. RNA sequencing showed that overexpression of CdWRKY2 in Arabidopsis activated the expression of genes involved in sucrose synthesis and metabolism, including sucrose synthase 1 (AtSUS1) and sucrose phosphate synthase 2F (AtSPS2F). CdSPS1, the homology gene of AtSPS2F in bermudagrass, was subsequently proven to be the direct target of CdWRKY2 by yeast one‐hybrid, electrophoretic mobility shift assay, and transient expression analysis. As expected, overexpression of CdSPS1 conferred cold tolerance in transgenic Arabidopsis plants, whereas silencing CdSPS1 expression enhanced cold sensitivity in bermudagrass. Besides, CdCBF1 whose expression was dramatically up‐regulated in CdWRKY2‐overexpressing bermudagrass hairy roots but down‐regulated in CdWRKY2‐silencing bermudagrass both under normal and cold stress conditions was confirmed as another target of CdWRKY2. Collectively, this study reveals that CdWRKY2 is a positive regulator in cold stress by targeting CdSPS1 and CdCBF1 promoters and activating their expression to coordinately mediate sucrose biosynthesis and CBF‐signalling pathway, which provides valuable information for breeding cold‐resistant bermudagrass through gene manipulation.

Comparison and Characterization of Oxidation Resistance and Carbohydrate Content in Cd-Tolerant and -Sensitive Kentucky Bluegrass under Cd Stress

Kentucky bluegrass (Poa pratensis L.), a turf grass species that is hypertolerant of cadmium (Cd), is a potential phytoremediation material for soil polluted with Cd. However, the mechanism of Cd phytotoxicity in Kentucky bluegrass is unclear. Here, we compared the phenotype, induction of oxidative stress, and structural and non-structural carbohydrate contents between a Cd-tolerant genotype (‘Midnight’, M) and Cd-sensitive genotype (‘Rugby’, R). The results showed that both genotypes accumulated more Cd in the roots, whereas the R genotype distributed more Cd into the leaves compared with the M genotype. In both genotypes, Cd inhibited the length and fresh weight of the leaves and roots; increased the peroxidase (POD) activity but inhibited ascorbate peroxidase (APX) and catalase (CAT) activity; and increased the superoxide radical (O2−), hydrogen peroxide (H2O2), and malondialdehyde (MDA) contents. However, the M genotype exhibited lower root length inhibition, and the H2O2 and MDA contents confirmed that the M genotype had increased Cd accumulation and resistance, while the R genotype exhibited a better distribution of Cd. Moreover, Cd stress significantly increased the soluble sugar, trehalose, and sucrose contents of both genotypes. Pectin, lignin, and cellulose were significantly increased to prevent the entry of Cd into the roots. The Cd-induced growth inhibition and physiological responses in Kentucky bluegrass were preliminarily explored herein, with the chelation of pectin, lignification, and antioxidant response being possible contributors to Cd detoxification in Kentucky bluegrass. In addition, the Cd-induced increase in trehalose, sucrose, and soluble sugar contents might play a pivotal role in the defense against Cd stress in Kentucky bluegrass.

A novel method of generating RNAi libraries for high‐throughput gene function analysis of creeping bentgrass

AbstractRNA interference (RNAi) is a powerful tool for gene function analysis, particularly for outcrossing polyploid species where simultaneous mutations of multiple alleles of a gene with similar but nonidentical sequences may not be readily achieved with the novel clustered regularly interspaced short palindromic repeats/Cas9 gene editing tools. The most effective RNAi strategy in plants is to use long hairpin RNAi (lhRNAi) constructs containing inverted repeats (IRs) of target genes. Previously, we used a Phi29‐Amplified RNAi Construct method to create a single lhRNAi construct that was shown to be highly effective in gene silencing in the model grass Brachypodium distachyon (L.) P.Beauv. Here, we describe a method of creating a library of lhRNAi constructs ready for high‐throughput gene function analysis in creeping bentgrass (Agrostis stolonifera L.), an important turfgrass species. A cDNA population in which salt‐responsive genes were enriched by suppression subtractive hybridization was used as the source of IRs. Sequencing of 13 randomly selected colonies from the lhRNAi library showed that the size of IRs varied from 184 to 994 bp, which is appropriate for RNAi, and nine of the IRs were shown to be homologous to known genes in closely related grasses. In addition to the demonstration of the proof‐of‐concept of creating an expression‐ready library, the salt stress‐specific lhRNAi library represents a valuable resource for studying the functions of salt‐responsive genes in creeping bentgrass. The method described here is broadly applicable to all plant species where an efficient plant transformation platform is available.

Alternative Engineered Soils and Seed Mixes Used for Seepage Troughs

Green Infrastructure measures such as seepage troughs are an integral part of sustainable urban rainwater management. In Austria, seepage troughs are currently almost exclusively produced with a 30 cm thick active soil filter passage made of topsoil. A standard seed mix is used as vegetation, which usually consists of only three different turfgrass species. During a three-year trial, engineered soils with improved properties (increased water storage capacity, infiltration rate and pore volume) were tested for their suitability as seepage troughs compared to topsoil. In addition to the standard turf seed mix, a flowering turf seed mix (34 species) and flowering meadow seed mix (53 species) were applied. The engineered and reference soils were analyzed for infiltration rate, vitality, cover ratio and inflorescence. The results were further assessed with the evaluation chart showing quantitatively the suitability of the tested soils for rainwater management. The investigations showed that engineered soils in combination with flowering meadow seed mix lead to the best results. Therefore, this type of vegetation for seepage troughs is recommended for future applications. The reference alternatives cannot be recommended.

Responses to elevated carbon dioxide for postdrought recovery of turfgrass species differing in growth characteristics

AbstractElevated CO2 concentration affects plant responses to drought, but its effects on poststress recovery for perennial grass species with different growth habits are unclear. The objective was to determine how stoloniferous and bunch‐type grass species may exhibit differential responses to elevated CO2 concentration during drought stress and postdrought recovery upon rewatering due to different growth characteristics. Stoloniferous creeping bentgrass (Agrostis stolonifera L.) ‘Penncross’ and bunch‐type tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] ‘Sitka’ were grown at ambient CO2 (400 μl L−1) or elevated CO2 concentration (800 μl L−1) repeated in four growth chambers for 28 d, subsequently subjected to either irrigation (control) or drought stress (irrigation completely withheld) for 28 d, and then rewatered for 18 d. During drought stress, both species exposed to elevated CO2 maintained higher turf quality, leaf water content, and membrane stability than plants at ambient CO2. Elevated CO2 caused significant increases in the viability of stolon–node meristematic tissues in creeping bentgrass under drought stress and rapid regeneration of daughter plants during rewatering, as shown by increased shoot biomass and percent turfgrass cover. Elevated CO2 had no significant effects on the viability of crowns with meristematic tissues in tall fescue during drought nor shoot biomass or percent turfgrass cover during rewatering. The stoloniferous grass species was more responsive to elevated CO2 compared to bunch‐type species for poststress recovery, as creeping bentgrass rapidly regrew and recovered from drought damages. Such information is of great importance for making appropriate turfgrass selections and breeding improvements in growth habits in areas with prolonged drought and the anticipated rising CO2 levels.

Turfgrass intercropping prevents non-point source pollution in sweet pepper production

Greenhouse vegetable production is one of the major non-point source (NPS) pollution due to its high fertilizer input and low nutrient use efficiency. Excessive salt and nutrient accumulation in the topsoil is responsible for the NPS pollution in greenhouse vegetable production. This study was designed to investigate the effects of turfgrass intercropping on NPS pollution in greenhouse sweet pepper production. The results showed that the pollution discharges via both surface runoff and leaching were significantly reduced by turfgrass intercropping. The reduction of pollution was associated with the capacity of turfgrass species in the absorption and accumulation of salts and nitrate. Paspalum vaginatum with preferential accumulations of nitrate and salts performed best results in the alleviation of soil salinity and NPS pollution. Paspalum vaginatum-intercropping decreased 51.2% of nitrate and 23.9% of electrical conductivity in the soil, 71.8% of total nitrogen, 54.9% of ammonia-nitrogen, 67.0% of nitrate-nitrogen, 68.8% of total phosphorus, 68.2% of phosphates, and 73.2% of potassium in the surface runoff, and 64.1% of total nitrogen, 53.4% of ammonia-nitrogen, 67.0% of nitrate-nitrogen, 44.3% of total phosphorus, 54.8% of phosphates, and 32.9% of potassium in the leachate. These results indicated that Paspalum vaginatum-intercropping could be a clean and sustainable solution to prevent NPS pollution in greenhouse vegetable production.

Transfer of resistance alleles from herbicide-resistant to susceptible grass weeds via pollen-mediated gene flow

AbstractThe objective of this paper was to review the reproductive biology, herbicide-resistant (HR) biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from HR to herbicide-susceptible grass weeds including barnyardgrass, creeping bentgrass, Italian ryegrass, johnsongrass, rigid (annual) ryegrass, and wild oats. The widespread occurrence of HR grass weeds is at least partly due to PMGF, particularly in obligate outcrossing species such as rigid ryegrass. Creeping bentgrass, a wind-pollinated turfgrass species, can efficiently disseminate herbicide resistance alleles via PMGF and movement of seeds and stolons. The genusAgrostiscontains about 200 species, many of which are sexually compatible and produce naturally occurring hybrids and hybrids with species in the genusPolypogon. The self-incompatibility, extremely high outcrossing rate, and wind pollination in Italian ryegrass clearly point to PMGF as a major mechanism by which herbicide resistance alleles can spread across agricultural landscapes, resulting in abundant genetic variation within populations and low genetic differentiation among populations. Italian ryegrass can readily hybridize with perennial ryegrass and rigid ryegrass due to their similarity in chromosome numbers (2n= 14), resulting in interspecific gene exchange. Johnsongrass, barnyardgrass, and wild oats are self-pollinated species, so the potential for PMGF is relatively low and limited to short distances; however, seeds can easily shatter upon maturity before crop harvest, leading to wider dispersal. The occurrence of PMGF in reviewed grass weed species, even at a low rate, is greater than that of spontaneous mutations conferring herbicide resistance in weeds and thus can contribute to the spread of herbicide resistance alleles. This review indicates that the transfer of herbicide resistance alleles occurs under field conditions at varying levels depending on the grass weed species.

Current Outlook on Ice Encasement Stress and Management Strategies in Turfgrasses

Ice encasement of perennial cool-season turfgrasses is a common problem in many northern regions of the world, and the incidence of ice encasement may increase with climate change. The objective of this review was to discuss recent advances in knowledge of how ice encasement affects turfgrass systems, current knowledge gaps, and current and potential future management strategies that can be used by turfgrass managers to mitigate ice encasement damage to turfgrass species that are sensitive to this stress. Ice encasement is a complex and severe stress, which if prolonged can include low temperatures, anoxia, toxic gases, toxic metabolic by-products, and other complications associated with the stress. Thus, research is needed to specifically identify responses of different turfgrasses to this stress. Species such as annual bluegrass (Poa annua) are widespread in the turfgrass industry but do not have adequate tolerance of ice encasement and extensive plant necrosis can occur. Repairs or renovations of large areas damaged by ice encasement is costly. Research on ice encasement of turfgrass species is needed to provide efficient recommendations and management strategies to the turfgrass industry.

Long-term Performance of Warm-season Turfgrass Species under Municipal Irrigation Frequency Restrictions

Landscape irrigation frequency restrictions are commonly imposed by water purveyors and municipalities to curtail domestic water use and to ensure adequate water supplies for growing populations during times of drought. Currently, published data are lacking concerning irrigation frequency requirements necessary for sustaining acceptable levels of turfgrass quality of commonly used warm-season turfgrass species. The objective of this 3-year field study was to determine comparative turfgrass quality of drought-resistant cultivars of four warm-season lawn species in the south–central United States under irrigation frequency regimes of 0, 1, 2, 4, and 8× monthly. Turfgrasses used in the study were based on previously reported drought resistance and included ‘Riley’s Super Sport’ (Celebration®) bermudagrass [Cynodon dactylon (L.) Pers.], ‘Palisades’ zoysiagrass (Zoysia japonica Steud.), ‘Floratam’ st. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and ‘SeaStar’ seashore paspalum (Paspalum vaginatum Swartz). During each growing season, slightly reduced irrigation volumes and bypassed events resulted from the 8× monthly treatment (34.95 cm, 38.13 cm, and 27.33 cm) compared with the 4× monthly treatment (35.36 cm, 40.84 cm, and 28.70 cm) in years 1, 2, and 3, respectively. For the once weekly treatment, the average fraction of reference evapotranspiration (ETo) supplied by effective rainfall and irrigation during the summer months was 1.22, 0.67, and 0.83 in years 1, 2, and 3, respectively, and was generally adequate to support acceptable turfgrass quality of all warm-season turfgrasses evaluated. Under the less than weekly irrigation frequency, st. augustinegrass and seashore paspalum generally fell to below acceptable quality levels because the average fraction of ETo supplied by effective rainfall and irrigation during the summer months of years 2 and 3 was 0.51, 0.39, and 0.26 for the 2× monthly, 1× monthly, and unirrigated treatments, respectively. Bermudagrass generally outperformed all other species under the most restrictive irrigation frequencies and also did not differ statistically from zoysiagrass. These results show that as irrigation frequency is restricted to less than once per week, species selection becomes an important consideration.

Investigating Factors Influencing Consumer Adoption of Low-input Turfgrasses

Important financial savings, along with reductions in environmental impact, can be achieved by planting lawns with low-input turfgrass species. Drawing on data from an online survey, this article provides empirical evidence on the factors that influence consumers’ willingness to adopt low-input turfgrasses. We group consumers into two segments: Willing Adopters and Reluctant Homeowners. Regardless of segment, consumers who regard maintenance requirements as more important were more willing to adopt low-input turfgrasses, whereas those who placed a higher value on appearance, were more unlikely to change to a low-input turfgrass, especially for Reluctant Homeowners. We categorized the barriers to adoption as follows: 1) Promotion, 2) Benefits and Accessibility, 3) Peer Effect, 4) Sample, and 5) Information. Our models predict that consumers’ willingness to adopt low-input turfgrass can be significantly increased if the identified barriers are removed. Based on our study, suppliers/retailers should adopt heterogeneous and multiple marketing strategies, such as promoting through multiple channels, informing and advising the public on proper information, providing photos or exhibiting in-store samples, triggering communication between different types of consumers, and providing incentives and improving accessibility, to target different consumer groups.

Growth and physiological potential of various turf grass species under graded shade levels

An study was carried out to evaluate the effects of graded shade levels on the growth and quality of turf grass species Cynodon dactylon (Bermuda grass), Zoysia matrella (Manilla grass), Stenotaphrum secundatum (St. Augustine grass), Paspalum notatum (Bahia grass), Paspalum vaginatum (Seashore Paspalum), Dactyloctenium aegyptium (Crowfoot grass), Axonopus affinis (Mat grass/Carpet grass) and Eremochloa ophiuroides (Centipede grass). These species grown under shade nets with different shading intensity of 25%, 50%, and 75% along with control (without shade net) were investigated at Division of Floriculture and Landscaping, IARI, New Delhi during 2017-19. Among the all species, Crowfoot grass and Zoysia found good under reduced irradiance conditionas compared to open conditions, while, St. Augustine, Bahia and Seashore Paspalum performed well from 25-50% reduced irradiance level but these were best under open conditions. Performance of Bermuda grass, Carpet grass and Centipede were not satisfactory under reduced irradiance level.

Silicon in turfgrass: A review

AbstractSilicon (Si) is a “quasi‐essential” element that helps plants to overcome various abiotic and biotic stresses. This review summarizes research which examined application of Si in turfgrass management and its impact on plant health. Research on inclusion of Si in turfgrass has largely centered upon three areas: plant disease suppression, improvement in wear tolerance, and reductions in drought and salinity stress. Of these, the ability of Si to reduce turf diseases has received the most attention, with applications of Si often reducing various diseases, including gray leaf spot, dollar spot, and brown patch, in creeping bentgrass, bermudagrass, perennial ryegrass, and St. Augustinegrass. One potential constraint to its effectiveness is that Si application rates for disease reduction are often quite high (e.g., rates as high as 400 to 2,000 kg Si ha–1). Responses were also variable with turfgrass species, soil type, and soil Si content, and the measured response was often not great enough to produce turf of desirable quality without additional use of fungicides. More research is needed in the area of Si and turf wear, as the use of Si to “harden” turfgrass and improve wear and ball roll is widely marketed in turfgrass maintenance. Further research is also needed to identify best soil extractants for measuring soluble Si and to calibrate this extractable Si for the determination of critical levels of soil Si across soil types and turfgrass species.

Investigation of cool‐season species, seeding rate, and nitrogen fertilization in sod production: I. Establishment and sod tensile strength

AbstractNew regulations aimed at reducing soil erosion along with changing building and residential codes are increasing sod demand, especially low‐input species, which are currently in very short supply and require research.Replicated field experiments were established in Indiana and Minnesota to quantify the effect of turfgrass species (strong creeping red fescue [Festuca rubra L. ssp. rubra Gaudin], Chewings fescue [F. rubra ssp. commutata Gaudin], tall fescue [F. arundinacea Schreb.], and Kentucky bluegrass [Poa pratensis L.]), seeding rate (1, 2, and 3 pure live seed cm−2), andN fertilization (98, 196, and 294 kg N ha−1 yr−1) on the production, quality, and harvest limitations of sod. Sod strength and handling were measured at sod harvests from 11 to 24 months after planting (MAP). Results indicate that strong creeping red fescue produces quality sod, likely because of the fast establishment and rhizomatous growth habit, and had higher or similar sod strength as Kentucky bluegrass at optimum N rates. Optimum N rates for strong creeping red fescue were two to three times lower than Kentucky bluegrass. Chewings fescue had less sod strength than strong creeping red fescue but more than tall fescue, and at times similar to Kentucky bluegrass. Overall, turfgrass species had the largest effect on sod strength and handling, while seeding or N rates had less impact on sod strength, especially with fine fescues. Sod growers may be able to produce fine fescue sod with good sod strength using lower seeding and N rates, and shorter production periods.

Response of Hybrid Bermudagrass and Manilagrass to Soil Moisture Using Water-table Depth Gradient Tanks

Previous research involving turfgrass response to soil moisture used methodology that may compromise root morphology or fail to control outside environmental factors. Water-table depth gradient tanks were employed in the greenhouse to identify habitat specialization of hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] and manilagrass [Zoysia matrella (L.) Merr.] maintained at 2.5 and 5.1 cm. Turfgrass quality (TQ), normalized difference vegetation index (NDVI), canopy temperature (CT), and root biomass (RB) were used as metrics for plants grown in monoculture in sandy clay loam soil. Mowing height did not affect growth of turfgrass species in response to soil moisture. Turfgrass quality, NDVI, and RB were greatest, whereas CT was lowest at wetter levels [27- to 58-cm depth to the water-table (DWT)] of each tank where plants were growing at or above field capacity. However, bermudagrass RB was greatest at 27-cm DWT, whereas manilagrass RB at 27-cm DWT was lower than RB at 42.5- to 73.5-cm DWT in 2013 and lower than all other levels in 2014. Both species responded similarly to droughty levels (120- to 151-cm DWT) of the tanks. Turfgrass quality, NDVI, and RB were lowest, whereas CT was highest at higher droughty levels. Bermudagrass may be more competitive than manilagrass when soil moisture is high whereas both species are less competitive when soil moisture is low.

Lipidomic metabolism associated with acetic acid priming-induced salt tolerance in Carex rigescens

Acetic acid priming may mitigate salt stress to plants by modulating lipid metabolism. Carex rigescens is a stress-tolerant turfgrass species with a widespread distribution in north China. The objective of this study was to figure out whether modification of lipid profiles, including the contents, compositions and saturation levels of leaf lipids, may contribute to acetic acid modulated salt tolerance in C. rigescens. Plants of C. rigescens were primed with or without acetic acid (30 mM) and subsequently exposed to salt stress (300 mM NaCl) for 15 days. Salt stress affected the physiological performance of C. rigescens, while acetic acid-primed plants showed significantly lower malondialdehyde content, proline content, and electrolyte leakage than non-primed plants under salt stress. Acetic acid priming enhanced the contents of phospholipids and glycolipids involved in membrane stabilization and stress signaling (phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, digalactosyl diacylglycerol, monogalactosyl diacylglycerol, and sulfoquinovosyldiacylglycerol), reduced the content of toxic lipid intermediates (free fatty acids) during subsequent exposure to salt stress. Furthermore, expression levels of genes involved in lipid metabolism such as CK and PLDα changed due to acetic acid priming. These results demonstrated that acetic acid priming could enhance salt tolerance of C. rigescens by regulating lipid metabolism. The lipids could be used as biomarkers to select for salt-tolerant grass germplasm.