High Shoot Density Research Articles

Suzhi 5: A New Hybrid Zoysiagrass Cultivar with High Shoot Density and Fine Leaf Texture

Suzhi 5: A New Hybrid Zoysiagrass Cultivar with High Shoot Density and Fine Leaf Texture

A hybrid beachgrass (Ammophila arenaria × A. breviligulata) is more productive and outcompetes its non-native parent species.

The ability of non-native species to successfully invade new ecosystems sometimes involves evolutionary processes such as hybridization. Hybridization can produce individuals with superior traits that give them a competitive advantage over their parent species, allowing for rapid spread. Here we assess growth, functional morphology, and species interactions between two non-native beachgrass species (Ammophila arenaria and A. breviligulata) and their recently discovered hybrid (A. arenaria × A. breviligulata) on the U.S. Pacific Northwest coast. We asked whether the hybrid beachgrass differs from its parent species in morphology and growth, whether it competes with its parent species, and, if so, what are the potential mechanisms of competition. Plant taxa were grown in low- and high-density monocultures and in two-way interactions in a common garden environment. We show that the hybrid grew taller and more densely, with greater total biomass, than either parent species. The hybrid was also the better competitor, resulting in the model prediction of competitive exclusion against A. breviligulata and, depending on its relative abundance, A. arenaria. The hybrid displays a mixed 'guerilla-phalanx' growth form that allows it to spread laterally and achieve high shoot densities, giving it a competitive advantage. Given the current dominance of A. breviligulata compared to A. arenaria in most of the region where these taxa co-occur, we suggest that the hybrid will grow, compete, and spread quickly with potentially widespread consequences for the two non-native Ammophila congeners and the dunes they build.

Turf-Type Tall Fescue Brown Patch Resistance as Influenced by Morphological Characteristics

Brown patch (caused by multiple species of Rhizoctonia and Rhizoctonia-like fungi) is one of the major turfgrass diseases impacting turf-type tall fescue [ Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] lawns during the summer season. Selection of tall fescue cultivars with brown patch resistance is an important cultural management practice to reduce disease severity and limit reliance on fungicides. A greenhouse experiment was conducted to quantify differences in brown patch resistance among 15 tall fescue cultivars and correlate disease resistance with plant morphological characteristics. Prior to R. solani inoculation, leaf blade width, sheath width and length, endophyte stem infection, and relative growth rate were measured. Disease resistance was determined as a percentage of the canopy blighted as measured using digital image techniques. Brown patch severity after 21 days in Experiments 1 and 2 ranged from 36.7 to 72.7% and 20.8 to 41.8%, respectively, among all cultivars. There were significant differences among morphological characteristics for the cultivars. Increased brown patch was associated with cultivars with a faster growth rate, wider sheath width, and decreased sheath length. This study demonstrates the importance of cultivar selection for reducing brown patch severity in tall fescue lawns. Additionally, tall fescue cultivars with higher shoot density and narrow leaves should not be avoided due to concerns of increased brown patch susceptibility.

EXAMINATION OF THE QUALITATIVE AND QUANTITATIVE PARAMETERS OF THE WHITE WINE GRAPE VARIETY KIRÁLYLEÁNYKA (FETEASCĂ REGALĂ) IN THE CASE OF DIFFERENT BUD LOADS

Grapes are grown on an area of 8.5 million hectares on Earth. Most of the world's grape production (60%) is located in the regions of Europe. The largest grape and wine-producing countries include France, Italy, and Spain. Viticulture in the Carpathian basin has a history of 2,000 years. The control of the Fetească regală variety which is a traditional Hungarian variety, the control reached the highest sugar content, with an exceptionally high value, and all three loaded treatments were significantly below this. The evolution of the acid content was exactly the opposite, the control reached the lowest value. In terms of survival, all load levels outperformed the control. In conclusion, in the case of Fetească regală, the bud load had both positive and negative effects on the content values, but it had only a positive influence in terms of yield. On the other hand, based on our observation, a high shoot density developed on the high-stressed stems in the plantation, which prevented the phytotechnical operations from being carried out.

Reproductive Responses to Increased Shoot Density and Global Change Drivers in a Widespread Clonal Wetland Species, Schoenoplectus americanus

The expansion of many wetland species is a function of both clonal propagation and sexual reproduction. The production of ramets through clonal propagation enables plants to move and occupy space near parent ramets, while seeds produced by sexual reproduction enable species to disperse and colonize open or disturbed sites both near and far from parents. The balance between clonal propagation and sexual reproduction is known to vary with plant density but few studies have focused on reproductive allocation with density changes in response to global climate change. Schoenoplectus americanus is a widespread clonal wetland species in North America and a dominant species in Chesapeake Bay brackish tidal wetlands. Long-term experiments on responses of S. americanus to global change provided the opportunity to compare the two modes of propagation under different treatments. Seed production increased with increasing shoot density, supporting the hypothesis that factors causing increased clonal reproduction (e.g., higher shoot density) stimulate sexual reproduction and dispersal of genets. The increase in allocation to sexual reproduction was mainly the result of an increase in the number of ramets that flowered and not an increase in the number of seeds per reproductive shoot, or the ratio between the number of flowers produced per inflorescence and the number of flowers that developed into seeds. Seed production increased in response to increasing temperatures and decreased or did not change in response to increased CO2 or nitrogen. Results from this comparative study demonstrate that plant responses to global change treatments affect resource allocation and can alter the ability of species to produce seeds.

Benthic Fish Communities Associated with Posidonia oceanica Beds May Reveal the Fishing Impact and Effectiveness of Marine Protected Areas: Two Case Studies in the Southern Tyrrhenian Sea

The effectiveness of a Marine Protected Area (MPA) is strongly related to its zoning design, management, and surveillance, and fish communities are considered indicators of conservation effects. Posidonia oceanica beds and fish assemblages were studied here to evaluate the fishing impacts and the effectiveness of the Marine Protected Areas (MPAs) of Santa Maria di Castellabate (SMC) and Costa degli Infreschi e della Masseta (CIM) in the South Tyrrhenian Sea, Italy. P. oceanica characteristics were estimated counting and collecting shoots, while fish communities were investigated by visual census. Multivariate analyses were performed to detect differences in fish assemblages among the MPA protection levels and seagrass characteristics. Significant differences in fish communities were observed between the depth and protection levels. The latter are probably due to the zoning design at SMC, which does not allow a spillover effect, and to fishing activities, as showed by the ABC curve results. Trophic analyses suggested the use of longlines at SMC, due to the dominance of planktivorous fish species, and of trammel nets at CIM, due to the great heterogeneity of the fish trophic groups. Shoot density and leaf length were significantly correlated with fish communities. CCA analyses showed omnivorous species, mostly belonging to the Sparidae family, correlated with the highest shoot densities, with their feeding habits mostly directed to crustaceans, while macro- and microinvertivores, mainly belonging to the Serranidae and Labridae families, correlated with the highest leaf lengths, where they sough shelter and feed. In conclusion, the data suggest that a zoning redesign at SMC and an increase in the surveillance of fishing activities at CIM might enhance the effectiveness of these MPAs, highlighting the role of fish community studies in identifying MPA efficiency issues and providing trustful guidelines for their management.

Posidonia oceanica (L.) Delile at Its Westernmost Biogeographical Limit (Northwestern Alboran Sea): Meadow Features and Plant Phenology

Meadows of the seagrass Posidonia oceanica inhabit most infralittoral bottoms of the Mediterranean Sea and are considered one of the main climax stages of the infralittoral environment. This seagrass has its western distributional limit along the coast of the Alboran Sea. Taking into account the decline of P. oceanica meadows and the global scenario of ocean warming, it becomes essential to know the structure, temporal dynamics, sexual reproduction and conservation status of this seagrass, across its geographical distribution, including the distribution boundaries where the meadows withstand limiting environmental conditions. In the present work, we studied the structure, phenology and flowering events of four P. oceanica meadows located in the northwestern Alboran Sea (close to the Strait of Gibraltar). Results indicate a decreasing trend of patch size, bathymetric range and number of leaves per shoot towards the Strait (and the Atlantic Ocean), as well as an increasing trend of shoot density and leaf height. Phenological parameters of the northwestern Alboran Sea P. oceanica meadows presented temporal dynamics similar to meadows from other locations within the biogeographical distribution of this seagrass, with similar or even less annual variability in the former. Although most of the studied P. oceanica meadows seem to present a good health status (BiPo index ~0.6) with high shoot densities and some flowering events, some of them showed evidence of regression.

Seasonal effects of edge and habitat complexity on eelgrass epifaunal assemblages

Habitat degradation and fragmentation reduce habitat structural complexity (e.g. amount of physical features) and increase habitat edges. While many studies have focused on the effects of habitat edges or complexity on biodiversity, relatively few have disentangled them or investigated their effects over time. We investigated how proximity to the edge of eelgrassZosterasubg.Zostera marinaLinnaeus, 1753 habitat, shoot density and their interactions across seasons can influence the diversity pattern of epifaunal assemblages in meadows situated in a Mediterranean lagoon (France). We used a combination of field sampling andin situmanipulations with artificial seagrass units (ASUs) mimicking low and high shoot densities. During autumn and spring, we found that shoot density, Z. marina biomass and leaf area index (LAI) were higher inside the meadows than at the edge, while epiphyte load was the highest in spring at the edges. Epifaunal abundance and diversity were higher at the edge than inside the meadow for both natural shoots—regardless of the epiphyte load—and ASUs in spring. In autumn, epifaunal abundance varied positively with ASU density, regardless of the position in the meadow. Our results also showed that edges and habitat complexity affect the epifaunal structure differently across seasons. Therefore, we suggest that recruitment of macrofauna is the main mechanism explaining a positive edge effect during spring. This work highlights the need to consider seasonal dynamics in the assessment of habitat fragmentation and degradation.

Morphological and distribution characteristics of \(\textit{Halophila beccarii}\) Aschers., 1871 in the Cau Hai lagoon, Thua Thien Hue province, Vietnam

Halophila beccarii Aschers., 1871 was one of the seagrass species that was vulnerable and threatened list by the International Union for Conservation of Nature (IUCN). During the survey period from March 2018 to September 2019, our results showed that H. beccarii was widely distributed in the Cau Hai lagoon and concentrated mainly in the Southeast area of the lagoon. The distribution of H. beccarii was seasonal. The species’ growth started from the early rainy season of the previous year until the end of the dry season of the following year. However, the period when the species had a high cover, biomass, and shoot density was from September 2018 to March 2019, and those values peaked in January 2019. The lowest cover and shoot density were recorded in November 2019, while the lowest biomass was in July 2019. The rainfall had a close positive correlation with the biomass of H. beccarii, while water salinity and water temperature were moderate negatively correlated with the biomass of the species.

Spatial overlap between lugworm (Arenicola marina) and eelgrass (Zostera marina) distribution in coastal waters: The role of environmental stressors

This study investigates the role of external physical and chemical stressors on the distribution of lugworms and eelgrass in sandy sediments at three shallow locations along the Danish coasts. The density of and spatial overlap between lugworm and eelgrass distribution were quantified during May–October in 2017 and 2018 and related to the potential role of two environmental stressors: Physical disturbance by waves and high levels of sulfide in the sediment. The inverse relationship between the density of lugworms and eelgrass shoots at the study sites suggests a general antagonistic distribution. The spatial overlap between these species was quantified by Levins’ index. The overlap was asymmetrical and much higher for lugworms than for eelgrass with the smallest overlap at the two locations mostly impacted by physical and chemical stress. Almost no eelgrass was present at these two impacted locations when lugworms exceeded 30 ind m−2, while the critical density approached 70 ind m−2 at the less impacted location. These results suggest that eelgrass is less resistant than lugworms to biological interactions when exposed to environmental stress. Eelgrass apparently require large and coherent meadows with high shoot density to tolerate multiple biological and environmental stressors. The knowledge acquired in this study improves the general understanding of species interactions in coastal ecosystems and is important for appropriate planning and management of future eelgrass restoration ventures.

Trait gradients inform predictions of seagrass meadows changes to future warming

Comparing populations across temperature gradients can inform how global warming will impact the structure and function of ecosystems. Shoot density, morphometry and productivity of the seagrass Posidonia oceanica to temperature variation was quantified at eight locations in Sardinia (western Mediterranean Sea) along a natural sea surface temperature (SST) gradient. The locations are spanned for a narrow range of latitude (1.5°), allowing the minimization of the effect of eventual photoperiod variability. Mean SST predicted P. oceanica meadow structure, with increased temperature correlated with higher shoot density, but lower leaf and rhizome width, and rhizome biomass. Chlorophyll a (Chl-a) strongly impacted seagrass traits independent of SST. Disentangling the effects of SST and Chl-a on seagrass meadow shoot density revealed that they work independently, but in the same direction with potential synergism. Space-for-time substitution predicts that global warming will trigger denser seagrass meadows with slender shoots, fewer leaves, and strongly impact seagrass ecosystem. Future investigations should evaluate if global warming will erode the ecosystem services provided by seagrass meadows.

Plant traits determining biogeomorphic landscape dynamics: A study on clonal expansion strategies driving cliff formation at marsh edges

AbstractDespite the well‐recognized importance of plant traits for biogeomorphic development of landscapes, our understanding remains limited of how species‐specific plant traits respond to and serve as drivers for the sedimentary dynamics within a biogeomorphic landscape. By manipulating a series of laboratory experiments, using mesocosms and a flume, we examined how species‐specific differences in expansion strategy, i.e., clonal step‐length of laterally expanding tillers, both respond to sediment type and drive cliff formation and persistence. We compared three marsh species, with contrasting clonal expansion traits, that are dominant in many estuaries worldwide: Spartina anglica, Scirpus maritimus, and Phragmites australis. Our results revealed that S. anglica tussocks tend to have high shoot density due to a short clonal expansion step‐length, whereas S. maritimus tussocks were much more diffuse and tend to have a longer clonal expansion step‐length. P. australis showed intermediate traits. Clonal expansion step‐length did show within‐species variation in response to sediment texture, but species‐specific differences remained the most important. Species with smaller clonal step‐lengths, such as S. anglica in this study, are more likely to induce cliffs at the marsh edge by driving formation of larger cliff heights and also having lower capacity to grow out from cliffs. Our findings thus illustrate how dynamic landscape features like cliffs at marsh edges depend on the clonal expansion traits of the dominant species. This enhances current understanding of the formation and development of marsh edges, and is instructive for understanding the role of species‐specific traits in driving distinct biogeomorphic landscape dynamics.

Velvet bentgrass putting green quality, water retention, and infiltration as affected by topdressing sand size and rate

AbstractVelvet bentgrass (Agrostis canina L.) putting greens require intensive sand topdressing programs for thatch management; however, their high shoot density combined with the low mowing heights make it challenging to maintain smooth, sand‐free putting surface when topdressing is applied at high rates. A field trial was initiated to determine the effects of sand size and topdressing rate on a ‘Greenwich’ velvet bentgrass putting green. Treatments were arranged in a 2 × 2 factorial and included a non‐topdressed control arranged in a randomized complete block design. The two factors were topdressing sand (medium‐coarse sand and medium‐fine sand) and topdressing rate (0.15 and 0.3 L m–2). Topdressing improved turf quality compared to the non‐topdressed control. Additionally, velvet bentgrass had better quality when topdressed at the rate of 0.3 L m–2 compared to 0.15 L m–2. Increasing topdressing rate from 0.15 to 0.3 L m–2 notably increased the quantity of unincorporated medium‐coarse sand remaining on the putting surface, whereas it often did not increase or only slightly increased the quantity of unincorporated sand with medium‐fine sand. Independent of sand size and rate, topdressing treatments maintained the top 0‐to‐3.8‐cm soil profile relatively dry and increased infiltration rate measured with mini disk infiltrometers. The lack of negative effects of medium‐fine sand on measured parameters and the minimum disruption to putting surface may encourage superintendents to apply greater quantities of topdressing for improving the performance of velvet bentgrass putting greens.

Growth and Photoacclimation Strategies of Three Zostera Species Along a Vertical Gradient: Implications for Seagrass Zonation Patterns

Seagrasses typically display vertical zonation patterns in tropical and temperate areas. In East Asia, three Zostera species (Z. japonica, Z. marina, and Z. caespitosa) are distributed at different water depths, leading to zonation patterns from intertidal to subtidal zones. The present study aimed to determine whether these patterns could be explained by differences in their physiological responses, morphological traits, and meadows architecture caused by depth variations. Intertidal Zostera japonica had the lowest shoot height and blade width and the highest shoot density, while subtidal Z. caespitosa exhibited the largest specific leaf area. Total carotenoid content and the total chlorophyll/total carotenoid ratio were significantly higher in Z. japonica than in Z. marina or Z. caespitosa. The average carbon stable isotope (δ13C) values were significantly less negative in Z. caespitosa than in Z. marina and Z. japonica. The average maximum relative electron transport rate was higher for Z. marina than for Z. japonica and Z. caespitosa, while the maximum quantum yield values were higher for Z caespitosa than for Z. japonica and Z. marina. The non-photochemical quenching (NPQ) of Z. japonica extinguished within 5-min following the rapid light curve, indicating that most of its NPQ was energy-dependent quenching (qE). The rapid light curve (RLC) parameters and leaf relaxation after RLC showed that Z. japonica is a high-light adapted species and Z. caespitosa is a low-light adapted one. Additionally, Z. caespitosa showed the lowest dark respiration values and Z. japonica, the highest, suggesting that Z. caespitosa can survive with low photosynthetic activity. These results suggested that interspecific variations in the morphological and physiological characteristics, photosynthetic pigments, and meadows architecture of three Zostera species were associated with vertical zonation patterns and likely explain their patterns.

The role of Cyperus alopecuroides Rottb. sedge in monitoring water pollution in contaminated wetlands in Egypt: a phytoremediation approach.

Many macrophytes have heavy metal phytoremediation potential from contaminated watercourses. Therefore, the present study investigated the seasonal potential of the sedge plant Cyperus alopecuroides to remediate heavy metals from contaminated water bodies. Water, sediment, and plant samples were collected from four contaminated watercourses and the uncontaminated Nile River. Summer was the blooming season of C. alopecuroides with the highest shoot density, leaf size, fresh production, and dry biomass, while winter represented the lowest growth season. The photosynthetic pigments were distinctly decreased in plants growing in contaminated compared to the uncontaminated sites. Plant roots accumulated concentrations of all measured heavy metals, except Ni, Cu, Zn, and Pb, more significant than the shoot. The maximum concentrations of Al, Ni, and Pb were recorded during spring, while the highest Cd, Cr, Fe, and Mn were recorded during summer. The bioconcentration factor (BCF) of all investigated metals (except Al) was > 1, while the translocation factor (TF) of all elements (except Pb) was ˂1. These results indicated the capability of C. alopecuroides for metal phytostabilization and considered the target species a powerful phytoremediator for monitoring water pollution in contaminated wetlands. In this context, the above- and belowground parts of C. alopecuroides should be harvested in summer for efficient phytoremediation.

Morphometry of leaf and shoot variables to assess aboveground biomass structure and carbon sequestration by different varieties of white mulberry (Morus alba L.)

Mulberry is economically important and can also play a pivotal role in mitigating greenhouse gases. Leaf and shoot traits were measured for Morus alba var. Kanmasi, M. alba var. Karyansuban, M. alba var. Latifolia, and M. alba var. PFI-1 to assess aboveground biomass (AGB) and carbon sequestration. Variety-specific and multivariety allometric AGB models were developed using the equivalent diameter at breast height (EDBH) and plant height (H). The complete-harvest method was used to measure leaf and shoot traits and biomass, and the ash method was used to measure organic carbon content. The results showed significant (p < 0.01) varietal differences in leaf and shoot traits, AGB and carbon sequestration. PFI-1 variety had the greatest leaf density (mean ± SE: 1828.3 ± 0.3 leaves tree−1), Karyansuban had the largest mean leaf area (185.94 ± 8.95 cm2). A diminishing return was found between leaf area and leaf density. Latifolia had the highest shoot density per tree (46.6 ± 1.83 shoots tree−1), total shoot length (264.1 ± 2.32 m), dry biomass (16.69 ± 0.58 kg tree−1), carbon sequestration (9.99 ± 0.32 kg tree−1) and CO2 mitigation (36.67 ± 1.16 kg). The variety-specific AGB models b(EDBH) and b(EDBH)2 showed good fit and reasonable accuracy with a coefficient of determination (R2) = 0.98–0.99, standard error of estimates (SEE) = 0.1125–0.3130 and root mean square error (RMSE) = 0.1084–0.3017. The multivariety models bln(EDBH) and (EDBH)0.756 showed good-fitness and accuracy with R2 = 0.85–0.86, SEE = 1.6231–1.6445 and RMSE = 1.609–1.630. On the basis of these findings, variety Latifolia has good potential for biomass production, and allometric equations based on EDBH can be used to estimate AGB with a reasonable accuracy.

Epiphytic hydroids on Posidonia oceanica seagrass meadows are winner organisms under future ocean acidification conditions: evidence from a CO2 vent system (Ischia Island, Italy)

Effects of ocean acidification (OA) on the plant phenology and colonization/settlement pattern of the hydrozoan epibiont community of the leaves of the seagrass Posidonia oceanica have been studied at volcanic CO2 vents off Ischia (Italy). The study was conducted in shallow Posidonia stands (2.5–3.5 m depth), in three stations on the north and three on the south sides of the vent’s area (Castello Aragonese vents), distributed along a pH gradient. At each station, 10–15 P. oceanica shoots were collected every three months for one-year cycle (Sept 2009–2010). The shoot density of Posidonia beds in the most acidified stations along the gradient (pH < 7.4) was significantly higher than that in the control area (pH = 8.10). On the other hand, we recorded lower leaf lengths and widths in the acidified stations in the whole year of observations, compared to those in the control stations. However, the overall leaf surface (Leaf Area Index) available for epiphytes under ocean acidification conditions was higher on the south side and on both the most acidified stations because of the higher shoot density under OA conditions. The hydrozoan epibiont community on the leaf canopy accounted for seven species, three of which were relatively abundant and occurring all year around (Sertularia perpusilla, Plumularia obliqua, Clytia hemisphaerica). All hydroids species showed a clear tolerance to low pH levels, including chitinous and non-calcifying forms, likely favoured also by the absence of competition for substratum with the calcareous forms of epiphytes selected against OA.

Historical changes in seagrass beds in a rapidly urbanizing area of Guangdong Province: Implications for conservation and management

Rapid urbanization leads to an accelerating decline of seagrass beds. The status of seagrass beds along the entire coastline of a rapidly urbanizing area, Guangdong Province, was examined to document the change in seagrass beds and to explore the determinants of seagrasses characteristics and their plasticity. Thirteen seagrass beds were newly discovered with a total area as 679.04 ha, whereas eleven known seagrass beds have decreased from 972.55 ha to 858.67 ha with seven of them having disappeared in recent decade primarily due to exacerbated construction of artificial shorelines and beach dams, increased nutrient inputs from fish caging and shrimp pond culture, oyster culture, mangrove planting and shellfish collection. The leaf nitrogen content of Halophila ovalis, which dominated the largest beds, increased from (2.09 ± 0.24)% in 2011 to (3.39 ± 0.18)% in 2017, indicating enhanced eutrophication. The optimum seawater dissolved inorganic nitrogen and dissolved inorganic phosphorus levels for Halophila beccarii were 40 μmol/L and 2.5 μmol/L, respectively. The standing stock and plant dimensions of H. beccarii were positively correlated with sediment mud content. Longer, wider leaves, and greater aboveground and belowground biomass were observed at lower salinities, indicating that H. beccarii prefers hyposaline habitats. High shoot density could induce intraspecific competition followed by self-thinning in H. beccarii, leading to reduced leaf area, aboveground and belowground biomass, and root length. Thus, long-term monitoring of seagrass beds along the rapidly urbanizing coastline of Guangdong Province is needed to unravel the mechanisms of decline and to develop effective management strategies.

Registration of ‘DALZ 1308’ zoysiagrass

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

Effect of Seagrass on Current Speed: Importance of Flexibility vs. Shoot Density

Water flow through seagrass beds transports nutrients, affects sediment stability and chemistry, and imposes hydrodynamic forces on shoots that alter canopy configuration. Past studies done under diverse conditions yielded conflicting results about the effects of shoot density on flow through seagrass bed canopies. We used eelgrass, Zostera marina, to study how the density of flexible shoots affect the hydrodynamics of seagrass beds (canopies) in unidirectional water flow. By exposing randomly-arranged shoots of uniform length to current velocities controlled in a flume, the effects of shoot density and downstream distance (position) could be determined without confounding factors. Comparison of velocity profiles within beds to those upstream of the beds showed that flow was slower in the beds. However, shoot density, position, and current velocity did not affect the percent reduction in flow velocity in a (sea)grass bed. Turbulence enhances mixing of substances carried in the water. Here, turbulence intensity (index of the importance of turbulent velocity fluctuations relative to average current velocity) was lower when ambient flow was faster, but was not affected by shoot density or position, Drag, the hydrodynamic force on a shoot that bends it over in the flow direction, provides another measure of how the canopy affects flow experienced by a shoot. Drag was not affected by current velocity, shoot density, or position in the bed. Gaps between shoots can enhance light and flow penetration into the canopy, but when shoots are bent over by flow, they can cover gaps. Faster ambient currents caused greater gap closure, which at each current speed was greater for high shoot densities. Thus, canopy gap closure did not correlate with percent flow reduction in grass beds or with drag on individual shoots, both of which were independent of shoot density and ambient current velocity. Since changing shoot density does not affect the flow in a grass bed exposed to a given ambient current, our results are inconsistent with the hypothesis that the high shoot densities observed in grass beds in habitats exposed to rapid flow are due to a direct, adaptive response of the grass to the flow environment.