Warm-season Turfgrass Research Articles

Genetic Diversity of Seashore Paspalum Revealed with Simple Sequence Repeat Markers

Seashore paspalum (Paspalum vaginatum) is an important warm-season turfgrass distributed in tropical and coastal areas. It has excellent resistance to abiotic stresses, such as salinity, drought, and low temperature. However, the research on genetic diversity of local P. vaginatum collections from China is limited. In this study, the genetic diversity among 58 P. vaginatum accessions from four different provinces in China and four cultivars were assessed using simple sequence repeat (SSR) markers. The results indicated that a total of 45 alleles were detected by 19 polymorphic markers, with a range of 2 to 4 and an average of 2.4 alleles per marker. The genetic similarity coefficients between each pair of the 58 P. vaginatum accessions and four cultivars ranged from 0.51 to 1.00, with an average of 0.77. The range of variation of Shannon diversity index of each SSR marker was 0.047 to 1.075, with an average of 0.486. The polymorphic information content of each SSR marker varies from 0.016 to 0.577, with an average of 0.249. The results of cluster analysis and principal component analysis (PCA) showed that 58 P. vaginatum accessions and four cultivars were divided into four groups. These results provide the theoretical basis for the genetic diversity assessments and molecular marker–assisted breeding of P. vaginatum species.

Leaf anatomical responses and chemical composition of warm-season turfgrasses to increasing salinity

As population growth and demands for potable water increase, use of low-quality or effluent sources of irrigation is becoming more prevalent. Because these water sources often contain elevated levels of dissolved salts, turfgrasses must increasingly possess mechanisms for coping with salinity stress. The objectives of this research were to utilize Scanning Electron Microscopy (SEM) combined with Energy Dispersive X-ray Spectroscopy (EDS) to explore and characterize anatomical and physiological responses of four salinity-tolerant cultivars/experimental lines of warm-season turfgrass species including bermudagrass (Cynodon ssp.), zoysiagrass (Zoysia ssp.), St. Augustinegrass (Stenotaphrum secundatum), and seashore paspalum (Paspalum vaginatum) to salinity stress. Grasses were grown in the greenhouse under two levels of salinity stress (control = 2.5 and 30 dS m−1) prior to examination of adaxial and cross-sectional leaf surfaces using SEM and EDS. St. Augustinegrass leaf anatomy did not differ between control and elevated salinity. In bermudagrass, salt glands were observed at the 30 dS m−1 salinity level, however, none were detected at the 2.5 dS m−1 level. Zoysiagrass appeared to possess constitutive salt gland development, which although were present under 2.5 dS m−1 salinity, noticeably increased in density with increasing salinity. Seashore paspalum did not possess salt glands, but rather, exhibited bladder-like structures, in which EDS detected high levels of Na following salinity stress. These findings highlight differences in anatomical responses to salinity stress among warm-season turfgrass species. The information may aid breeders and physiologists in developing a more comprehensive understanding of warm-season turfgrass anatomical responses to salinity stress.

Physiological and transcriptomic analyses reveal the mechanisms underlying the salt tolerance of Zoysia japonica Steud

BackgroundAreas with saline soils are sparsely populated and have fragile ecosystems, which severely restricts the sustainable development of local economies. Zoysia grasses are recognized as excellent warm-season turfgrasses worldwide, with high salt tolerance and superior growth in saline-alkali soils. However, the mechanism underlying the salt tolerance of Zoysia species remains unknown.ResultsThe phenotypic and physiological responses of two contrasting materials, Zoysia japonica Steud. Z004 (salt sensitive) and Z011 (salt tolerant) in response to salt stress were studied. The results show that Z011 was more salt tolerant than was Z004, with the former presenting greater K+/Na+ ratios in both its leaves and roots. To study the molecular mechanisms underlying salt tolerance further, we compared the transcriptomes of the two materials at different time points (0 h, 1 h, 24 h, and 72 h) and from different tissues (leaves and roots) under salt treatment. The 24-h time point and the roots might make significant contributions to the salt tolerance. Moreover, GO and KEGG analyses of different comparisons revealed that the key DEGs participating in the salt-stress response belonged to the hormone pathway, various TF families and the DUF family.ConclusionsZoysia salt treatment transcriptome shows the 24-h and roots may make significant contributions to the salt tolerance. The auxin signal transduction family, ABA signal transduction family, WRKY TF family and bHLH TF family may be the most important families in Zoysia salt-stress regulation.

The complete chloroplast genome of Chrysopogon aciculatus (Retz.) Trin

Chrysopogon aciculatus (Retz.) Trin. is one of the most important warm-season turfgrass and one of the distribution centers in China, widely distributed in tropical regions of South China. In this study, the complete chloroplast genome sequence of C. aciculatus was determined from Illumina pair-end sequencing data. The complete chloroplast genome sequence of C. aciculatus is 140,696 base pairs (bp) in length, including one large single-copy region (LSC, 82,667 bp), one small single-copy region (SSC, 12,539 bp), and a pair of inverted repeat regions (IRs) of 22,745 bp. Besides, the complete chloroplast genome contains 134 genes, including 85 protein-coding genes, 41 tRNA genes, and 8 rRNA genes. Phylogenetic analysis showed that C. aciculatus (Retz.) Trin. was most closely related to C. serrulatus. The complete chloroplast genome will provide reference for the further investigation and research of C. aciculatus.

The ethylene responsive factor CdERF1 from bermudagrass (Cynodon dactylon) positively regulates cold tolerance

Cold stress is one of the major environmental factors that limit growth and utilization of bermudagrass [Cynodon dactylon (L.) Pers], a prominent warm-season turfgrass. However, the molecular mechanism of cold response in bermudagrass remains largely unknown. In this study, we characterized a cold-responsive ERF (ethylene responsive factor) transcription factor, CdERF1, from bermudagrass. CdERF1 expression was induced by cold, drought and salinity stresses. The CdERF1 protein was nucleus-localized and encompassed transcriptional activation activity. Transgenic Arabidopsis plants overexpressing CdERF1 showed enhanced cold tolerance, whereas CdERF1-underexpressing bermudagrass plants via virus induced gene silencing (VIGS) method exhibited reduced cold resistance compared with control, respectively. Under cold stress, electrolyte leakage (EL), malondialdehyde (MDA), H2O2 and O2− contents were reduced, while the activities of SOD and POD were elevated in transgenic Arabidopsis. By contrast, these above physiological indicators in CdERF1-underexpressing bermudagrass exhibited the opposite trend. To further explore the possible molecular mechanism of bermudagrass cold stress response, the RNA-Seq analyses were performed. The result indicated that overexpression of CdERF1 activated a subset of stress-related genes in transgenic Arabidopsis, such as CBF2, pEARLI1 (lipid transfer protein), PER71 (peroxidase) and LTP (lipid transfer protein). Interestingly, under-expression of CdERF1 suppressed the transcription of many genes in CdERF1-underexpressing bermudagrass, also including pEARLI1 (lipid transfer protein) and PER70 (peroxidase). All these results revealed that CdERF1 positively regulates plant cold response probably by activating stress-related genes, PODs, CBF2 and LTPs. This study also suggests that CdERF1 may be an ideal candidate in the effort to improve cold tolerance of bermudagrass in the further molecular breeding.

Couch smut, an economically important disease of Cynodon dactylon in Australia

Couch smut, caused by Ustilago cynodontis, is an economically important disease of Cynodon dactylon, the most widely planted warm season turfgrass in Australia. The disease is distributed across all states and mainland territories of Australia, and is found worldwide wherever the host plant is present. The most characteristic disease symptoms are expressed at the flowering stage, when the inflorescence is partly or entirely destroyed and covered by a mass of black powdery spores. However, there are also less obvious impacts of the disease on plant growth such as a more erect growth habit, and a reduced rate of stolon extension and root development, leading to lower levels of tolerance of the turf to wear during usage, and greater amounts of wastage during harvest due to the roll breaking at points of infection. Ustilago cynodontis was first described nearly 130 years ago but pathogen biology and disease epidemiology are still poorly understood, hindering development of disease management strategies. We review the current knowledge and understanding of couch smut biology, the history of its occurrence, distribution and impact, and existing disease management practices to identify the gaps in knowledge that require further research.

Nonchemical annual bluegrass (Poa annua) management in zoysiagrass via fraise mowing

AbstractContinued reliance on chemical methods for controlling annual bluegrass has resulted in many populations evolving resistance to PRE and POST herbicides, particularly in warm-season turfgrass species such as zoysiagrass. Soil seedbank management is critically important when managing herbicide-resistant weeds. Fraise mowing (also spelled fraze, frase, and fraize) is a new turfgrass cultivation practice designed to remove aboveground biomass while allowing turf to regrow vegetatively. We hypothesized that this process would remove annual bluegrass seed and therefore be a mechanical means of controlling annual bluegrass in turfgrass. Zoysiagrass field plots were fraise-mowed in June 2015 only, June 2016 only, June 2015 and June 2016, or left untreated. The fraise mower was configured to remove the uppermost 25 mm of plot surface (i.e., 15-mm verdure and 10-mm soil). Annual bluegrass infestation was quantified in April following fraise mowing via grid count. Soil cores (10.8 cm diameter) were extracted from each plot after grid count data were collected to assess effects of fraise mowing on the soil seedbank. Moreover, replicated subsamples (7.6 L) of debris generated during fraise mowing were collected to better understand weed seed content removed during the fraise mowing process. Fraise mowing in June offered a slight reduction (24%) in annual bluegrass cover the following April. Whereas 28% of the seed in fraise-mowing debris consisted of annual bluegrass, there was no difference in the quantity of annual bluegrass seed remaining in the soil seedbank among fraise-mowed and non–fraise-mowed plots. Although fraise mowing may help to temporarily reduce existing annual bluegrass infestations via mechanical removal, the frequency and depth we studied did not effectively reduce the seedbank. Fraise mowing is a useful tool for providing mechanical suppression of annual bluegrass but it is not a replacement for properly timed herbicide applications.

A novel basic helix-loop-helix transcription factor, ZjICE2 from Zoysia japonica confers abiotic stress tolerance to transgenic plants via activating the DREB/CBF regulon and enhancing ROS scavenging.

ZjICE2 works as a positive regulator in abiotic stress responses and ZjICE2 is a valuable genetic resource to improve abiotic stress tolerance in the molecular breeding program of Zoysia japonica. The basic helix-loop-helix (bHLH) family transcription factors (TFs) play an important role in response to biotic or abiotic stresses in plants. However, the functions of bHLH TFs in Zoysia japonica, one of the warm-season turfgrasses, remain poorly understood. Here, we identified ZjICE2 from Z. japonica, a novel MYC-type bHLH transcription factor that was closely related to ICE homologs in the phylogenetic tree, and its expression was regulated by various abiotic stresses. Transient expression of ZjICE2-GFP in onion epidermal cells revealed that ZjICE2 was a nuclear-localized protein. Also, ZjICE2 bound the MYC cis-element in the promoter of dehydration responsive element binding 1 of Z. japonica (ZjDREB1) using yeast one-hybrid assay. A phenotypic analysis showed that overexpression of the ZjICE2 in Arabidopsis enhanced tolerance to cold, drought, and salt stresses. The transgenic Arabidopsis and Z. japonica accumulated more transcripts of cold-responsive DREB/CBFs and their downstream genes than the wild type (WT) after cold treatment. Furthermore, the transgenic plants exhibited an enhanced Reactive oxygen species (ROS) scavenging ability, which resulted in an efficient maintenance of oxidant-antioxidant homeostasis. In addition, overexpression of the ZjICE2 in Z. japonica displayed intensive cold tolerance with increases in chlorophyll contents and photosynthetic efficiency. Our study suggests that ZjICE2 works as a positive regulator in abiotic stress responses and the ICE-DREB/CBFs response pathway involved in cold stress tolerance is also conserved in Z. japonica. These results provide a valuable genetic resource for the molecular breeding program especially for warm-season grasses as well as other leaf crop plants.

Approaches to scheduling water allocations to kikuyugrass grown on a water repellent soil in a drying-climate

Water allocation is a principal planning method for managing water supplies to agricultural and horticultural land in drying climates. Regulatory bodies often establish the water allocation amount, but its distribution during the irrigation season is left to the land manager’s discretion. We evaluated approaches to best manage water allocations to a warm-season turfgrass [Pennisetum clandestinum (Holst. Ex Chiov)] grown on a free-draining sand prone to surface (0–25 mm) soil water repellence in a Mediterranean climate in south-western Australia under ‘deficit irrigation’, in a two-year field study. The three factorial experiment consisted of three levels for each treatment applied to plots (10 m2) of kikuyugrass: water allocation (5000, 6250 or 7500 kL ha−1 yr−1), irrigation schedule, and soil wetting agent rate (nil, recommended ‘label’ rate, double recommended ‘label’ rate), and was replicated three times. The irrigation schedules were based on historical net evaporation at the site, and then refined monthly using in-season net evaporation data or measurements of soil water content. Kikuyugrass growth and color was adequate when irrigated using the current regional water allocation (7500 kL ha−1 yr−1) under a low wear situation and to a lesser extent when the water allocation was lowered to 6250 kL ha−1 yr−1. Application of a soil wetting agent diminished water repellence and improved kikuyugrass color for 7500 or 6250 kL ha−1 yr−1 water allocations. Distributing a water allocation based on historical monthly net evaporation rates was a simple and effective scheduling approach to maintaining a warm-season turfgrass.

Hydraulic Fluid Type and Remediation Practices on Hydraulic Leak Injury to Creeping Bentgrass Putting Greens

Equipment with hydraulic implements are often used to maintain turfgrass surfaces. Hydraulic implements can malfunction and lead to leaks or spills of hydraulic fluid, which is phytotoxic to turfgrass. Previous research has documented extensively hydraulic fluid injury on warm-season turfgrasses, but these effects have not been evaluated on cool-season grasses and warrant further investigation. Therefore, the objectives of this study were to compare phytotoxicity of petroleum, vegetable, and synthetic hydraulic fluids on a creeping bentgrass (Agrostis stolonifera) putting green and to evaluate the influence of postapplication remediation practices on reducing turfgrass injury. Turfgrass injury was evaluated over a 4-week period in 2011 and 2012 after simulated hydraulic fluid leak and remediation practices were applied. Complete necrosis was observed after 28 days for all hydraulic fluid types. However, water rinse (RO) or detergent soap solution drench followed by brushing in/water rinse (SBR) remediation practices effectively eliminated turfgrass injury by the end of the 4-week period for synthetic polyalkylene glycol fluid treatments, but no other hydraulic fluid types. Turfgrass managers might consider the synthetic polyalkylene glycol hydraulic fluid tested in this study as a less phytotoxic alternative to petroleum hydraulic fluids if a remediation practice is implemented after a leak or spill.

Identification of a cold tolerant mutant in seashore paspalum (Paspalum vaginatum)

Seashore paspalum (Paspalum vaginatum Swartz) is a commonly used warm-season turfgrass with superior salt tolerance. Low temperature is one of the major abiotic stresses limiting its growth and plantation regions. A protocol for ethyl methane sulphonate (EMS) induced mutations from embryogenic callus and selection of seashore paspalum mutant line with enhanced cold tolerance was established in the study. Treatment of embryogenic callus with 5 h of 0.8% EMS resulted in an approximate 50% survival rate of callus, which was used for inducing mutations from embryogenic callus of seashore paspalum. One mutant line (A6) with enhanced cold tolerance was selected and identified from about 10,000 regenerated plantlets. A6 had lower TEL50 (the temperature resulted in 50% electrolyte leakage) and higher survival rate than its wild type (WT) plants after 7 days of cold acclimation. Antioxidant defense system was responsive to low temperature in both genotypes, while higher CAT activity was maintained in A6 than in WT after 3 days of cold treatment. Among four DREB1/CBF genes induced by cold treatment, higher levels of DREB1A, DREB1D, DREB1E transcripts were observed in A6 than in WT. Free amino acids concentrations in response to cold treatment also showed difference between A6 and WT. The results suggest that the response of DREB1/CBFs expression, CAT activity, and free amino acids concentrations to cold is differentially altered in A6 compared with WT, which is associated with the enhanced cold tolerance in A6. A mutant line with enhanced cold tolerance was selected by EMS mutagenesis in seashore paspalum. It had higher catalase activity and DREB1/CBFs transcripts with altered free amino acids than WT.

Measurement of Genetic Diversity of Chinese Seashore Paspalum Resources through Morphological and Sequence-related Amplified Polymorphism Analysis

Seashore paspalum (Paspalum vaginatum) is a notable warm-season turfgrass. Certain germplasm resources are distributed in the southern regions of China. The objectives of this study were to investigate the genetic diversity and genetic variation of Chinese seashore paspalum resources. Morphological characteristics and sequence-related amplified polymorphism (SRAP) markers were used to assess genetic relationships and genetic variation among 36 germplasm resources from China and six cultivars from the United States. The results showed significant variation for 13 morphological characteristics among 42 tested seashore paspalum accessions, and that the phenotypic cv was, in turn, turf height > turf density > internode length > inflorescence density > leaf width > reproductive branch height > spikelet width > leaf length > spikelet number > inflorescence length > internode diameter > inflorescence width > spikelet length. According to the morphological characteristics and cluster analysis, 42 seashore paspalum accessions were divided into six morphological types. In total, 374 clear bands were amplified using 30 SRAP primer combinations; among these bands, 321 were polymorphic with 85.83% polymorphism. SRAP marker cluster analysis showed that 42 seashore paspalum accessions were grouped into seven major groups, with a genetic similarity coefficient ranging from 0.4385 to 0.9893 and genetic distance values ranging from 0.0108 to 0.8244. The high level of genetic diversity occurred among Chinese germplasm, and the genetic distance was relatively high between Chinese germplasm and cultivars introduced from the United States. The patterns in morphological trait variations and genetic diversity will be useful for the further exploitation and use of Chinese seashore paspalum resources.

Flowering Persistence and Pollinator Attraction of Early-spring Bulbs in Warm-season Lawns

Early-spring flowering bulbs can increase biodiversity while adding color to lawns and other grassy areas. However, few studies have investigated whether bulbs can flower and persist in warm-season lawns or provide feeding habitat for pollinating insects. Thirty early-spring flowering bulbs, including species of Anemone, Chionodoxa, Crocus, Eranthis, Hyacinthus, Ipheion, Iris, Leucojum, Muscari, and Narcissus, were established in bermudagrass (Cynodon dactylon L. Pers) and buffalograss [Buchloe dactyloides (Nutt.) J.T. Columbus] lawns in late autumn 2015 in Fayetteville AR. Bulbs were assessed over three growing seasons for flowering characteristics, persistence, and their ability to attract pollinating insects. A growing degree day model was also developed to predict peak flowering times in our region. Numerous bulb entries produced abundant flowers in bermudagrass and buffalograss lawns in the first year after planting, but persistence and flower production were reduced in both the second and third years of the trial. Five bulbs persisted for multiple years in both turfgrass species and continued to produce flowers, including Crocus flavus Weston ‘Golden Yellow’ (crocus), Leucojum aestivum L. (spring snowflake), Narcissus (daffodil) ‘Baby Moon’, Narcissus ‘Rip Van Winkle’, and Narcissus ‘Tete-a-Tete’. Several bulbs, primarily crocuses and Muscari spp. (grape hyacinth), were also observed to attract pollinating insects, principally honey bees (Apis mellifera). These results demonstrate that some early-spring bulbs can persist in competitive warm-season turfgrasses, while providing pollinator forage, but species and cultivar selection is critical for long-term success.

Zoysia japonica MYC type transcription factor ZjICE1 regulates cold tolerance in transgenic Arabidopsis

ICE1 (Inducer of CBF Expression 1) is a regulator of cold-induced transcriptome, which plays an important role in plant cold response pathway. To enhance the cold tolerance of Zoysia japonica, one of the warm-season turfgrasses, it is helpful to understand the cold response mechanism in Zoysia japonica. We identified stress-responsive ZjICE1 from Zoysia japonica and characterized its function in cold stress. Our results showed that ZjICE1 shared the typical feature of ICE homolog proteins belonging to a nucleic protein. Transactivation activity assay revealed that ZjICE1 bound to the MYC cis-element in the ZjDREB1’s promotor. The ZjICE1 overexpressed transgenic Arabidopsis showed enhanced tolerance to cold stress with an increases in SOD, POD, and free proline content and reduction in MDA content. They also induced the transcripts abundance of cold-responsive genes (CBF1, CBF2, CBF3, COR47A, KIN1, and RD29A) after cold treatment. These results suggest that ZjICE1 is a positive regulator in Zoysia japonica plant during cold stress and can be a useful gene for the molecular breeding program to develop the cold tolerant zoysiagrass. Furthermore, the ZjICE1 also conferred resistance to salt and drought stresses, providing the better understanding of the basic helix-loop-helix (bHLH) gene family in abiotic stress responses.

Salinity Tolerance and Recovery Attributes of Warm-season Turfgrass Cultivars

As population growth places greater pressures on potable water supplies, nonpotable recycled irrigation water is becoming widely used on turfgrass areas including golf courses, sports fields, parks, and lawns. Nonpotable recycled waters often have elevated salinity levels, and therefore turfgrasses must, increasingly, have good salinity tolerance to persist in these environments. This greenhouse study evaluated 10 commonly used cultivars representing warm-season turfgrass species of bermudagrass (Cynodon spp.), zoysiagrass (Zoysia spp.), st. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and seashore paspalum (Paspalum vaginatum Swartz) for their comparative salinity tolerance at electrical conductivity (EC) levels of 2.5 (control), 15, 30, and 45 dS·m–1. Salinity treatments were imposed on the grasses for 10 weeks via subirrigation, followed by a 4-week freshwater recovery period. Attributes, including turf quality, the normalized difference vegetation index (NDVI), canopy firing, and shoot biomass reductions were evaluated before and after salinity stress, as well as after the 4-week freshwater recovery period. Results showed considerable differences in salinity tolerance among the cultivars and species used, with the greatest tolerance to elevated salinity noted within seashore paspalum cultivars and Celebration® bermudagrass. In comparison with growth in 2.5-dS·m–1 control conditions, increased shoot growth and turf quality were noted for many bermudagrass and seashore paspalum cultivars at 15 dS·m–1. However, st. augustinegrass and some zoysiagrass cultivars responded to elevated salinity with decreased growth and turf quality. No cultivars that had been exposed to 30- or 45-dS·m–1 salinity recovered to acceptable levels, although bermudagrass and seashore paspalum recovered to acceptable levels after exposure to 15-dS·m–1 salinity. More severe salinity stress was noted during year 2, which coincided with greater greenhouse temperatures relative to year 1.

Effects of isolates of Clarireedia jacksonii and Clarireedia monteithiana on severity of dollar spot in turfgrasses by host type

Dollar spot, caused by four Clarireedia species (formerly Sclerotinia homoeocarpa), is a devastating disease that affects many turfgrass species throughout North America. Proper classification and genetic diversity of Clarireedia spp. was debated for the past several decades until recently when the organism was reclassified in 2018. Previous studies have shown that there is little genetic diversity except for isolates obtained from warm season hosts in Florida and the southern United States. Our research confirms the presence of isolates obtained from cool-season (C3) turfgrass species which are consistent with the recently classified species Clarireedia jacksonii; and a second, distinct sub-group of isolates obtained solely from warm-season (C4) turfgrass species, which are consistent with the recently classified species Clarireedia monteithiana. Additionally, we have documented the coexistence of these two species throughout the transition zone of the United States, extending as far north as Virginia, with both species present among adjacent stands of C3 and C4 turfgrass species in the same locale. Despite previous documentation of genetically distinct isolates occurring in the United States, there have been no reports on the variability in growth of the two named species over a range of temperatures, nor have these species been evaluated for their ability to infect both C3 and C4 turfgrass species. The effects of temperature on the lack of in vitro isolate growth for both C. jacksonii and C. monteithiana isolates were most noticeable at 10 and 35 °C, where all isolates exhibited little to no growth after 60 h. Cross inoculation experiments showed that both species are capable of infecting and inciting disease on both the preferred and alternative host, and that C. jacksonii isolates are more virulent on both C3 and C4 host grasses than C. monteithiana isolates. The results of this study will have implications for dollar spot management strategies on bermudagrass as well as an increased need for turfgrass breeders to develop dollar spot resistance cultivars of bermudagrass, particularly for those used in climates extending north of the transition zone.

Effects of Sub-Optimal Temperatures on Seed Germination of Three Warm-Season Turfgrasses with Perspectives of Cultivation in Transition Zone

Warm-season turfgrass species prevail in tropical and subtropical areas, but can also be grown in the transition zone. In this case, cold tolerance is a key aspect for germination and successful turfgrass establishment. The germination response to sub-optimal temperatures was investigated for Cynodon dactylon (cvs Jackpot, La Paloma, Transcontinental, Yukon, Riviera), Buchloe dactyloides (cv SWI 2000) and Paspalum vaginatum (cv Pure Dynasty). Four temperature regimes were applied, i.e., 20/30 °C, 15/25 °C, 10/20 °C and 5/15 °C, with a 12:12 h (light:dark) photoperiod. Germination assays were performed twice, with six replicates (Petri dishes) per treatment in each experiment, fifty seeds per dish. The final germinated percentages at last inspection time (FGP) were obtained for each Petri dish and processed by using a generalized linear mixed model (binomial error and logit link). Germination curves were fitted to each Petri dish by using time-to-event methods and germination rates (GR) for the 10th, 20th and 30th percentiles were derived and used to fit a linear thermal-time model. For all cultivars, FGP decreased with decreasing mean daily temperatures. Base temperatures (Tb) ranged between 11.4 °C and 17.0 °C, while the thermal time to obtain 30% germination ranged from 51.3 °C day for SWI 2000 to 144.0 °C day for Pure Dynasty. The estimated parameters were used to predict germination time in the field, considering the observed soil temperatures in Legnaro. The estimated date for the beginning of germination in the field would range from early April for SWI 2000 and Transcontinental to mid-May for Riviera. These results might be used as a practical support for planning spring sowing, which is crucial for successful turfgrass establishment, especially without irrigation.

TURF AND PLAYING QUALITY TRAITS OF SOME NEW TURFGRASS ALTERNATIVES IN A MEDITERRANEAN ENVIRONMENT

In an attempt to investigate the turfgrass and playing quality characteristics of some newly introduced warm season turf grasses and traditional cool season sports turf mixture, classical and contemporary techniques were imposed on the turfgrass experimental plots of the research area of Department of Field Crops, Agriculture Faculty of Ege University, Bornova/Izmir/Turkey. Some warm season turfgrasses (Cynodon dactylon cv. SR9554, Cynodon dactylon x Cynodon transvaalensis cv. Tifway-419, Paspalum vaginatum cv. Sea Spray and Zoysia japonica cv. Zenith) and traditional cool season sports turf mixture were tested in terms of visual turf quality and playing quality traits (ball rebound, ball roll and shock absorption) on a monthly and seasonal bases for three years under Mediterranean environmental conditions. Significant variations were determined among the turfgrass alternatives in all traits except years. It was concluded that Tifway-419 and Sea Spray turf grasses were the most successful and promising alternatives compared to the other options under Mediterranean environmental conditions.

Transcriptome-guided identification and functional characterization of key terpene synthases involved in constitutive and methyl jasmonate-inducible volatile terpene formation in Eremochloa ophiuroides (Munro) Hack

Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) is a warm-season turfgrass, widely planted in residential lawns and recreational fields. Here, we uncovered three major terpenes released from the shoots of Eo: (E)-β-ocimene (6%), α-muurolene (87.8%), and eremophilene (6.2%). Methyl jasmonate (MeJA) treatment increased the emission of monoterpenes, including (E)- and (Z)-β-ocimene, limonene, and myrcene, as well as sesquiterpene blends of (E)-caryophyllene, α-copaene, (+)-cyclosativene, and α-farnesene. RNA sequencing analysis predicted 14 putative Eo terpene synthase (EoTPS) genes, and two full-length EoTPS were successfully amplified: Eo7816 (1722 bp) and Eo6039 (1701 bp). Phylogenetic analysis revealed that Eo7816 and Eo6039 belonged to the clades of TPS-b and TPS-a, respectively. The Arabidopsis transgenic plants overexpressing Eo7816 exclusively released (E)-β-ocimene (96%) with (Z)-β-ocimene and myrcene. In contrast, Eo6039-overexpressing Arabidopsis plants emitted significant amounts of α-muurolene (69.4%) and eremophilene (21.8%). Together, we demonstrated that the two TPSs play roles in producing major volatile terpenes in Eo.

Biology and Management of Doveweed (Murdannia nudiflora) in Ornamental Crop Production

Doveweed is a common grass-like warm-season annual weed in Florida landscapes, container nurseries, and other agricultural production systems. This article is written for green industry professionals and others to aid in the identification and management of doveweed in and around ornamental plants. Information on doveweed management in warm-season turfgrass species can be found at https://edis.ifas.ufl.edu/pdffiles/AG/AG39500.pdf.