Global Distributions of Clarireedia Species and their In Vitro Sensitivity Profiles to Fungicides

Dollar spot is reported to be caused by multiple Clarireedia species and is a serious problem on many turfgrasses around the world. To our knowledge, the distribution of different Clarireedia species and their sensitivity profiles to fungicides remains unknown. In this study, a total of 275 isolates were characterized by ITS sequence. Amounts of 124, 59 and 75 isolates were identified as C. jacksonii, C. monteithiana and C. paspali, respectively, while each species of C. homoeocarpa and C. bennettii had only five isolates. Four and three isolates were identified as two potential new species, which remained to be further characterized. C. jacksonii and C. monteithiana were distributed worldwide, while C. paspali was restricted to China. Of the isolates with host information, 81% (93/115) and 19% (22/115) of C. jacksonii isolates were collected from C3 and C4 plants, respectively, 97% (56/58) of the C. monteithiana isolates were collected from C4 plants and all C. paspali isolates were collected from C4 plants. The coexistence of different Clarireedia species on the same C4 host type in the same locales was found in Shanghai (Paspalum vaginatum), Jiangsu (Paspalum vaginatum) and Florida (Cynodon dactylon). The study revealed that differential fungicide sensitivity patterns were observed in different species in Clarireedia for the first time. Similar differential sensitivity profiles were also found in the locales with coexistence of at least two species. The findings from this study suggest that the adjacent coexistence of different Clarireedia species and the differential fungicide sensitivity profiles of different species will complicate dollar spot disease control.

Effects of overseeding times on different warm-season turfgrasses: Visual turf quality and some related characteristics

The sustainability of warm-season turfgrass species in winter dormancy is a major concern in Mediterranean ecology. The concept of overseed a lawn has been still new for many developing countries such as Turkey as part of a regular maintenance. Therefore, a 2-year study was conducted at the experimental fields of Ege University, Izmir/Turkey during 2014-2016 years to compare the effects of four different overseeding times (September 15, September 30, October 15 and October 30) on four warm season turfgrass species (Cynodon dactylon cv. SR9554, Cynodon dactylon × Cynodon transvaalensis cv. Tifway-419, Paspalum vaginatum cv. Sea Spray and Zoysia japonica cv. Zenith) by measuring visual turf quality (1-9 score) and some related characteristics as texture (mm), cover (1-9 score), weed infestation (1-9 score) and colour (1-9 score). ‘50% cv. Troya+50% cv. Esquire’ perennial ryegrass (Lolium perenne L.) mixture was used for overseeding in trial. According to results, visual turf quality performance of 6.0 scores and above were obtained from all treatments. We concluded that October 15 should be most suitable time for overseeding applications. Additionally, L. perenne L. can be practiced successfully in Mediterranean region in order to eliminate the concerns of warm-season turfgrasses in the winter dormancy period observed in cold temperatures. Highlights - No gaps were formed in plots and high coverage degrees were maintained during overseeding periods in all treatments. - Homogeneous spring transition was occurred from Lolium perenne L. to warm-season turfgrass species in all overseeding times. - Visual turf quality performance of 6.0 scores and above which is acceptable level were obtained from all overseeding times. - Better results were obtained from overseeding applications on Paspalum vaginatum and Cynodon dactylon × Cynodon transvaalensis. - The different results among the warm-season turfgrass species can provide effective information for future research studies.

The genome of stress tolerant crop wild relative Paspalum vaginatum leads to increased biomass productivity in the crop Zea mays

A number of crop wild relatives can tolerate extreme stressed to a degree outside the range observed in their domesticated relatives. However, it is unclear whether or how the molecular mechanisms employed by these species can be translated to domesticated crops. Paspalum (Paspalum vaginatum) is a self-incompatible and multiply stress-tolerant wild relative of maize and sorghum. Here we describe the sequencing and pseudomolecule level assembly of a vegetatively propagated accession of P. vaginatum. Phylogenetic analysis based on 6,151 single-copy syntenic orthologous conserved in 6 related grass species placed paspalum as an outgroup of the maize-sorghum clade demonstrating paspalum as their closest sequenced wild relative. In parallel metabolic experiments, paspalum, but neither maize nor sorghum, exhibited significant increases in trehalose when grown under nutrient-deficit conditions. Inducing trehalose accumulation in maize, imitating the metabolic phenotype of paspalum, resulting in autophagy dependent increases in biomass accumulation.

Intraspecific variation in elemental accumulation and its association with salt tolerance in Paspalum vaginatum

Most plant species, including most crops, perform poorly in salt-affected soils because high sodium levels are cytotoxic and can disrupt uptake of water and important nutrients. Halophytes are species that have evolved adaptations to overcome these challenges and may be a useful source of knowledge for salt tolerance mechanisms and genes that may be transferable to crop species. The salt content of saline habitats can vary dramatically by location, providing ample opportunity for different populations of halophytic species to adapt to their local salt concentrations; however, the extent of this variation, and the physiology and polymorphisms that drive it, remain poorly understood. Differential accumulation of inorganic elements between genotypes or populations may play an important role in local salinity adaptation. To test this, we investigated the relationships between population structure, tissue ion concentrations and salt tolerance in 17 “fine-textured” genotypes of the halophytic turfgrass seashore paspalum (Paspalum vaginatum Swartz). A high-throughput ionomics pipeline was used to quantify the shoot concentration of 18 inorganic elements across three salinity treatments. We found a significant relationship between population structure and ion accumulation, with strong correlations between principal components derived from genetic and ionomic data. Additionally, genotypes with higher salt tolerance accumulated more K and Fe and less Ca than less tolerant genotypes. Together these results indicate that differences in ion accumulation between P. vaginatum populations may reflect locally adapted salt stress responses.

Intraspecific variation in elemental accumulation and its association with salt tolerance in Paspalum vaginatum

Most plant species, including most crops, perform poorly in salt-affected soils because high sodium levels are cytotoxic and can disrupt uptake of water and important nutrients. Halophytes are species that have evolved adaptations to overcome these challenges and may be a useful source of knowledge for salt tolerance mechanisms and genes that may be transferable to crop species. The salt content of saline habitats can vary dramatically by location, providing ample opportunity for different populations of halophytic species to adapt to their local salt concentrations; however, the extent of this variation, and the physiology and polymorphisms that drive it, remain poorly understood. Differential accumulation of inorganic elements between genotypes or populations may play an important role in local salinity adaptation. To test this, we investigated the relationships between population structure, tissue ion concentrations (i.e., ionomic profiles) and salt tolerance in 17 fine-textured genotypes of the halophytic turfgrass seashore paspalum (Paspalum vaginatum Swartz). A high-throughput ionomics pipeline was used to quantify the shoot concentration of 18 inorganic elements across three salinity treatments. We found a significant relationship between population structure and ion accumulation, with strong correlations between principal components derived from genetic and ionomic data. Additionally, genotypes with higher salt tolerance accumulated more K and Fe and less Ca than less tolerant genotypes. Together these results indicate that differences in ion accumulation between P. vaginatum populations may reflect locally adapted salt stress responses.

Performance of Two Seashore Paspalum (Paspalum vaginatum Sw.) Varieties Growing in Shallow Green Roof Substrate Depths and Irrigated with Seawater

The continuing decline in global drinking water reserves necessitates finding alternative water sources for turfgrass irrigation, especially in southern semi-arid Mediterranean countries. The aim of the present study was to evaluate the potential of using seawater for irrigating two varieties of seashore paspalum (Paspalum vaginatum Sw.), “Marina” and “Platinum ΤΕ”, growing in shallow green roof substrates, and to determine their recuperative capacity after the termination of the salt stress period. The greenhouse study comprised of 48 lysimeters equipped with extensive green roof layering. Treatments included: (i) two substrate depths (7.5 cm or 15 cm) and (ii) three seawater irrigation regimes (7 mm, 15 mm, or 45 mm every two days). Measurements included the determination of green turf cover (GTC) as well as the leaching fraction (LF) and leachate electrical conductivity (ECL) draining from the lysimeters. It was found that during the 46-d salt stress period, none of the seawater irrigation regimes managed to maintain acceptable GTC levels for both seashore paspalum varieties. Increasing the green roof substrate depth from 7.5 cm to 15 cm resulted in GTC improvement. During the recovery period, the use of potable water as irrigation source improved GTC levels. After 40 d the recovery was complete since GTC exceeded 90% in all treatments for both varieties. Regression curves correlating GTC response to ECL can be used to estimate the leaching requirements of turfgrasses grown in shallow green roof systems when irrigated with saline water.

Tropical Signalgrass Control in Seashore Paspalum

Tropical signalgrass (Urochloa subquadripara) is a mat-forming grass with relatively coarse texture. It is characterized by hairy sheaths and leaf blades plus a short fringe of hair present on the ligule. Tropical signalgrass control in Florida has been challenging for turf managers, in part, due to monosodium methanearsonate (MSMA) restrictions. Previous research indicates fall herbicide applications to be more effective than summer applications; however, fall applications typically do not allow turfgrass adequate time to fill in bare spots prior to winter. Two studies were conducted on seashore paspalum (Paspalum vaginatum) roughs at The Oaks golf course in Osprey, FL in summer 2019 comparing single and combination treatments of amicarbazone, carfentrazoneethyl, sulfentrazone, flazasulfuron, and quinclorac for control of tropical signalgrass. All treatments were applied with a non-ionicsurfactant at 0.25% v/v. In both studies a sequential application of each treatment was made 21 days after initial treatment (DAIT). Rating dates were 4 June, 25 June, 16 July, and 13 August, corresponding to 0, 21, 42, and 70 DAIT, respectively. In study one, 10 weeks after initial treatment (WAIT), amicarbazone + carfentrazone-ethyl + sulfentrazone at 0.23 + 0.0076 + 0.068 lb ai/acre (0.26 + 0.0085 + 0.076 kg ai/ha), respectively, provided best control (~60%). For study two, at 6 and 10 WAIT, tropical signalgrass control of >50% was not achieved. Overall, long-term postemergence control of tropical signalgrass with summer applications of herbicides tested was incomplete, even with multiple applications; however, amicarbazone + carfentrazone-ethyl + sulfentrazone showed potential as a control option.