Percent Green Cover Research Articles

Mowing Height and Fertility Regime Effects on Tall Fescue Turf in the Pacific Northwest

The western portion of the Pacific Northwest is known for being dry in the summer and cool and humid in the other months. Tall fescue is valued for its drought and heat tolerance, making it a desirable choice in regions where water is scarce and often restricted by legislation during periods of drought in the summer. However, cool and humid climates make it challenging to manage tall fescue in the winter because unacceptable quality is often observed due to low-temperature diseases and thinning in turf. A field trial was initiated in Autumn 2020 in Corvallis, OR, USA to assess the effects of mowing height as well as fertility timing and rate on tall fescue performance. Two mowing heights of 5.1 and 7.6 cm, four seasonal fertility timings, and three levels of annual N rates of 98, 196, and 294 kg·ha−1·yr−1 were evaluated using a 2 × 4 × 3 factorial experiment in a strip-plot design. Quantitative data of percent green cover and normalized difference vegetation index (NDVI) suggest that autumn fertilization is needed in cool, humid areas where tall fescue is actively growing in the winter months. The annual fertilization rate of 294 kg·ha−1·yr−1 N produced higher green turf cover and NDVI, compared with 98 or 196 kg·ha−1·yr−1 N. Furthermore, divergent effects of mowing heights were observed during winter compared with other months, suggesting that tall fescue could be mowed lower at 5.1 cm during cool, humid winter months and higher at 7.6 cm in other seasons for better overall turfgrass growth and less winter disease and thinning. Our research provides practical cultural practices for managing tall fescue turf in the Pacific Northwest or similar climates.

Nutrition of Florida lawns when summer fertilizer blackout period is enforced

AbstractIn Florida, multiple counties restrict the application of N to turfgrass and landscapes during the summer rainy season. These summer fertilizer blackout periods could impact turfgrass quality and the functionality of warm‐season turfgrass species. A 2‐year study was conducted at the University of Florida's Fort Lauderdale Research and Education Center (FLREC) and West Florida Research and Education Center (WFREC) to assess turfgrass performance of ‘Floratam’ and ‘Classic’ St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] as well as ‘Empire’ and ‘Palisades’ zoysiagrass (Zoysia japonica Steud.), respectively, receiving no N fertilization during summer blackout period using eight fertilization programs compared to an unfertilized control. Visual quality, normalized difference vegetation index, percentage green cover, and dark green color index were assessed biweekly. Roots were collected before and after the fertilizer blackout period to determine root dry weight. While no differences were detected in St. Augustinegrass at the FLREC and zoysiagrass at the WFREC, all fertilized treatments except urea reached and maintained an acceptable turfgrass quality (≥6) throughout the blackout period, suggesting that urea by itself was not sufficient to support an optimal turfgrass performance during a fertilizer blackout period. The addition of P to nutrition programs did not influence turfgrass quality. Results indicate that N source is the most important factor to sustain turfgrass quality year‐round in Florida.

Traffic Tolerance of Perennial Ryegrass (Lolium perenne L.) Cultivars as Affected by Nitrogen Fertilization

Perennial ryegrass (Lolium perenne L.) is one of the most widely used species for sports fields in temperate climates because of its high wear tolerance. However, wear tolerance of cultivars may vary according to local environmental conditions and turfgrass management. In this study, we evaluated the wear tolerance of six perennial ryegrass cultivars (Adagio, Apple SGL, Equate, Firebird, Principal 2, Tetradark) under two fertility treatments (100 or 200 kg N⋅ha−1⋅yr−1) over 2 years. The field trial was performed at the Experimental Agricultural Farm at the University of Padova in northeastern Italy in a silty loam soil. Plots were arranged in a randomized complete block with three replications and subjected to three traffic events per week using a sports field wear simulator. Turfgrass quality (TQ), percent green cover (PGC), and normalized difference vegetation index (NDVI) were recorded every 2 weeks and averaged over each month. Although perennial ryegrass cultivars responded differently to wear stress, the higher nitrogen (N) rate positively affected the TQ of them all. ‘Tetradrak’ and ‘Equate’ had the lowest TQ, especially during the active growing seasons (spring and autumn). However, ‘Tetradark’ was particularly negatively affected during the cool fall months. The impact of a higher N fertilization rate on PGC and NDVI appeared to be more pronounced in spring than in fall. Furthermore, slight differences among cultivars and treatments were observed in summer and winter when temperatures were a limiting growth factor.

Genetic Variability of Traffic Tolerance and Surface Playability of Bermudagrass (Cynodon spp.) under Fall Simulated Traffic Stress

Bermudagrasses (Cynodon spp.) are the most preferred turfgrass species for athletic fields in the southern and transition zones of the United States. Developing and using bermudagrasses with superior traffic tolerance and surface playability under trafficked conditions benefits turfgrass managers, athletes, and sport organizations. A 2-year field study was conducted in Stillwater, OK, to quantify the genetic variability of traffic tolerance and surface playability from a population composed of two commercially available and 87 experimental interspecific hybrid bermudagrasses under fall simulated traffic stress. The experiment design was a randomized complete block design with three replications. Plots were subjected to 60 simulated cleat traffic events for 6 weeks in the fall of 2019 and 2020 using a Baldree traffic simulator. Bermudagrasses were evaluated for turfgrass quality (TQ), normalized difference vegetation index (NDVI), fall percent green cover (FPGC), shear strength (SS), and surface hardness (SH) after 3 and 6 weeks of traffic. Spring green-up percent green cover (SGPGC) was evaluated in the spring of 2020 and 2021. Except for SH, significant entry effects were found for all parameters and reliability estimates were moderate to high (i2 = 0.49 to 0.68) under simulated trafficked conditions. Experimental entries 17-4200-19X13, 17-4200-19X9, 17-4200-36X19, 17-5200-4X11, 18-7-2, 18-7-6, 18-8-2, 18-8-3, 18-8-7, 18-9-2, OSU1101, and OSU1664, and TifTuf® had excellent traffic tolerance. Entries 18-8-7, OSU1101, OSU1675, TifTuf®, and Tahoma 31® demonstrated high SS. There was a large group of entries that had consistent early spring green-up across both years, including Tilin#5, 18-9-8, OKC1221, OSU1257, OSU1318, OSU1337, OSU1406, OSU1439, OSU1651, OSU1675, Tahoma 31®, and TifTuf®. OSU1101 was the entry ranking in the top statistical grouping most often throughout the study. Findings illustrated the possibility of improving traffic tolerance and SS through breeding and using phenotypic selection could reliably select bermudagrass genotypes with improved traffic tolerance and SS in the transition zone.

Assessing unmanned aerial vehicle‐based imagery for breeding applications in St. Augustinegrass under drought and non‐drought conditions

AbstractThe use of imagery collected from small unmanned aerial vehicles (UAVs) in turfgrass breeding has rapidly increased, as has the demand to develop drought‐resistant cultivars. However, prior to adopting UAVs to help guide turfgrass selection under drought stress conditions, a clear understanding of the value and predictive ability of imagery‐based turfgrass characterization is required. In St. Augustinegrass, a major warm‐season turfgrass species grown in the Southeastern United States, limited research has been published about characterizing drought stress using aerial imagery. Specifically, no efforts have compared the various vegetation indices (VIs) commonly used to evaluate vegetative health in other species and sought to identify the most useful index for phenotyping drought stress traits in St. Augustinegrass. In this study, traditional ground‐based approaches for measuring percent green cover (PGC) and normalized difference vegetation index (NDVI) were compared against their UAV‐derived counterparts as well as 13 VIs under drought and non‐drought conditions, and broad‐sense heritability (H2) was calculated. A population of 115 genotypes from a ‘‘Raleigh’’ × ‘‘Seville’’ cross were analyzed at two environmentally distinct field sites in North Carolina. At both sites, a significant relationship between ground‐based and UAV‐derived measurements for PGC and NDVI was observed before and during drought (r = 0.82 to 0.95) and suggests a clear advantage to using UAVs for phenotyping drought traits given the reduced time and labor costs compared to on‐ground efforts. Among all VIs compared, UAV‐derived NDVI (NDVI‐U) showed strong correlation with the PGC taken on the ground (r > 0.85), a similar trend over time, and a higher H2 estimate under drought conditions, suggesting that NDVI‐U has the potential to assist in the selection of St. Augustinegrass genotypes with the best phenotypic response to drought. Implementing UAV imagery‐based high‐throughput methods will allow breeders to evaluate germplasm with unbiased quantitative consistency, quickly and thoroughly, and with increased frequency—all without sacrificing the response to selection potential.

Tall Fescue Mowing Height Effects under Simulated Athletic Field Traffic

Tall fescue (Schedonorus arundinaceus) offers an alternative to kentucky bluegrass (Poa pratensis) for use on athletic fields. Tall fescue has the ability to withstand athletic field traffic, but little is known about the best management practices such as optimal height of cut (HOC). A 2-year study was conducted on established ‘Snap Back’ tall fescue grown over a native soil root zone to determine optimal HOC under simulated athletic field traffic. Plots were maintained at various HOC treatments (1.5, 2, or 3 inches) for the duration of the growing season. Twenty-five simulated traffic events were applied each fall with a modified Baldree traffic simulator. The percentage of green cover (GC) loss per traffic event by HOC varied between years. In 2017, the 1.5-inch HOC improved traffic tolerance (–1.7% GC per event) compared with the other HOC treatments (–2.6% GC per event) in terms of percentage of GC. In 2018, the HOC did not have an impact on traffic tolerance. Differences in traffic tolerance between years could be a result of differences in precipitation (78 mm in 2017, 6 mm in 2018) during the period when traffic occurred, which suggest that the lower HOC performs better under wet conditions compared with the greater HOC. There were no differences among treatments for the safety variables measured (surface hardness, rotational resistance, and soil moisture).

Comparative study of morphological, anatomical, cell wall compositional, and leaf elemental features of traffic‐tolerant versus traffic‐sensitive tall fescue (Festuca arundinacea)

AbstractTurfgrass traffic tolerance is essential for athletic field aesthetics and performance. Tall fescue (Festuca arundinacea Scherb.; syn. Schedonorus arundinaceus [Schreb.] Dumort., nom. cons.) is utilized on athletic fields due to its high tolerance to traffic stress. However, the physiochemical characteristics and mechanisms associated with traffic tolerance are not understood. Therefore, identifying traffic‐tolerant characteristics would be beneficial for selecting future turfgrass varieties. The objective of this study was to identify morphological, mechanical, and anatomical characteristics of traffic‐tolerant and traffic‐sensitive tall fescue varieties. Simulated traffic was applied to the 2018 National Turfgrass Evaluation Program tall fescue trial at the Iowa State Horticulture Research Station. A modified Baldree traffic simulator applied 24 simulated traffic events yearly during August and September 2019–2021. The four most traffic‐tolerant/traffic‐sensitive varieties, each, were selected based on the average final percent green cover after simulated traffic. Evaluations included leaf width and thickness, leaf angle, plant density, intercellular void space, and maximum and final resistive force of three‐point bending testing. Additionally, cell wall constituents, hemicellulose, cellulose, lignin, and concentration of three elements (nitrogen [N], calcium [Ca], potassium [K]) were quantified in the leaf. Compared to traffic‐sensitive varieties, the traffic‐tolerant group (SE5302, SE5STAR, BGR‐TF3, and PST‐5DART) exhibited wider leaves (3.53 vs. 2.73 mm), lower plant density (23.4 vs. 38.6 plants 7 cm−2), larger intercellular void space (29,532 vs. 10,051 μm2), greater maximum resistive force (0.607 vs. 0.350 N), and greater final displacement force (0.531 vs. 0.288 N). The identification of these characteristics could be used as selection criteria for traffic‐tolerant varieties of tall fescue in future.

Seed treatment affected establishment and yield in two pennycress lines

IntroductionOilseed pennycress (Thlaspi arvense L.) is an emerging biofuel crop for use in the aviation industry that has potential as a rotational crop in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] cropping sequences. Ensuring autumn emergence of pennycress after early broadcast seeding is key because this practice may result in uneven spatial distribution due to the small seed size and variable germination, soil contact, and moisture availability. The objective of this research was to evaluate the impact of five seed treatments and enhancements on autumn establishment in two pennycress lines (MN106NS and tt8-t/ARV1) in broadcast seeding compared with no treatment.MethodsTested treatments were (i) gibberellic acid (GA) soak, (ii) fludioxonil fungicide, (iii) pelleting with diatomaceous earth and a commercial binder, (iv) fungicide plus pelleting, or (v) fungicide plus pelleting with GA added to the binder. Seeds were planted at nine sites in four U.S. states to assess establishment (stand counts and percentage canopy cover) in the autumn and spring and seed yield after maturity.ResultsThe MN106NS line had greater plants m−2 and percent green cover with treatments that included GA compared to the control. Line tt8-t/ARV1 had reduced stands when pelleted compared to the untreated, and establishment was unchanged when treated with GA compared to the untreated. Pelleting treatments without GA were not beneficial for stand establishment of either line. Seed yield for MN106NS was 20% greater than the untreated when treated with GA only or pelleted. Seed yield for tt8-t/ARV1 did not increase over the untreated with any treatment and was reduced by 20%–40% when pelleted.DiscussionThese results suggest minimal benefit of seed treatment and pelleting for the tested lines under broadcast seeding, though black-seeded lines may still benefit from GA treatment. Plant establishment and yield were negatively correlated with total precipitation post-planting, suggesting that excessive rainfall post-planting (>60 mm) may impede establishment when broadcast seeded.

Kuala Lumpur Green Space Fragmentation Index Analysis and Green Corridors Suggestion using Geographic Information System

More than half of the world’s population lives in urban areas, and the United Nations has projected that nearly all future global population growth will occur in urban areas. Urbanization has caused rapid industrial, transportation and residential development at the expense of environmental deterioration. Activities involving large-scale land clearances are conducted to satisfy human needs for expansion. The clearances have caused green area fragmentation and patches, especially in the rapidly developing urban areas. This study is aimed at detecting the current coverage of green space in the metropolitan city of Kuala Lumpur (KL), the capital city of Malaysia and monitor its fragmentation using a very high spatial resolution satellite data. Green cover which includes trees, grass, and shrubs of KL was first extracted from the SPOT 6 data using Object Oriented method which can classified the green covers. The fragmented green spaces in KL were analyzed using a range of fragmentation indices namely Number of Patches, Edge Density, Class Area, Total Landscape Area, Mean Patch Size and Mean Shape Index using the Patch Analyst tool embedded in the ArcGIS software version 10.0 to study the patterns of green patches. The connectivity of the green patches was studied and proposed to overcome the fragmentation problems. Kuala Lumpur (KL) was chosen as the case study as it is a rapidly developing city with a significant loss of green space. The urban green spaces were more fragmented as there were more built-up areas. Results of the green cover extraction reveal that the KL city centre had the lowest percentage of green cover (2.09 %) area to the urban area compared to the other five zones (Sentul Manjalara 5.03 %, Wangsa Maju Maluri 6.09 %, Damansara Penchala 11.22 %, Bukit Jalil Seputeh 7.07 % and Bandar Tun Razak Sg Besi 7.42 %). Since KL’s urban growth predominantly consists of compact building blocks, the highest land use was believed to be for commercial purposes. Around 66% of industrial and commercial activities are concentrated in the KL city centre, resulting in a diverse green space structure and a growing gap between patches in the city centre zone. The green patches were then connected to create green corridors in the city centre. Several parameters were involved in the analysis, including area, distance, types of land use (green areas and place of interest for the origin and destination), slopes under 7% value (topology with flat surfaces) and road networks. The origin and destination points were analyzed using the network analysis method in Quantum GIS to produce routes with the shortest path algorithm. Results showed that six routes were suitable for designing green corridors in the KL city centre area connecting green spaces and places of interest. All six routes were analyzed every 400 meters using Google Earth Street View to see the surrounding facilities. The Green Corridor Route 6 was the most appropriate for people, as it included parks and places of interest for city dwellers. The green corridor could then be promoted as a walkable area to minimize carbon emissions in the urban area, reducing the urban heat island phenomenon and increasing green connectivity for a better urban life.

Identification of new cold tolerant Zoysia grass species using high-resolution RGB and multi-spectral imaging

Zoysia grass (Zoysia spp.) is the most widely used warm-season turf grass in Korea due to its durability and resistance to environmental stresses. To develop new longer-period greenness cultivars, it is essential to screen germplasm which maintains the greenness at a lower temperature. Conventional methods are time-consuming, laborious, and subjective. Therefore, in this study, we demonstrate an objective and efficient method to screen maintaining longer greenness germplasm using RGB and multispectral images. From August to December, time-series data were acquired and we calculated green cover percentage (GCP), Normalized Difference Vegetation Index (NDVI), Normalized Difference Red Edge Index (NDRE), Soil-adjusted Vegetation Index (SAVI), and Enhanced Vegetation Index (EVI) values of germplasm from RGB and multispectral images by applying vegetation indexs. The result showed significant differences in GCP, NDVI, NDRE, SAVI, and EVI among germplasm (p < 0.05). The GCP, which evaluated the quantity of greenness by counting pixels of the green area from RGB images, exhibited maintenance of greenness over 90% for August and September but, sharply decrease from October. The study found significant differences in GCP and NDVI among germplasm. san208 exhibiting over 90% GCP and high NDVI values during 153 days. In addition, we also conducted assessments using various vegetation indexes, namely NDRE, SAVI, and EVI. san208 exhibited NDRE levels exceeding 3% throughout this period. As for SAVI, it initially started at approximately 38% and gradually decreased to around 4% over the course of these days. Furthermore, for the month of August, it recorded approximately 6%, but experienced a decline from about 9% to 1% between September and October. The complementary use of both indicators could be an efficient method for objectively assessing the greenness of turf both quantitatively and qualitatively.

Evaluation of Different Aerification Methods for Ultradwarf Hybrid Bermudagrass Putting Greens

Aerification and topdressing are important cultural management practices that help prevent organic matter accumulation and soil compaction in golf greens. However, these practices result in surface disruption and decreased putting quality during recovery. A 2-year study was conducted on a ‘TifEagle’ hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) putting green to determine the effect of different aerification methods and topdressing materials on soil properties and turfgrass recovery. Plots were aerified four times per year (May to Aug.) using 1/2-inch hollow tines, 1/4-inch hollow needle tines, hollow tines 2X + hollow needle tines 2X, or sand injection, and topdressed with either 90:10 (sand:peat) or green-dyed sand. Visual quality, normalized difference vegetation index, percent green cover, dark green color index (DGCI), surface firmness and volumetric water content were measured before initial aerification and at 7 and 21 days after aerification. Saturated hydraulic conductivity (Ksat) and organic matter (OM) content were measured monthly. Aerification with hollow tines and hollow tines 2X + hollow needle tines 2X resulted in lower firmness and OM and higher Ksat compared with hollow needle tines and sand injection. Sand injection showed the highest percent green cover and similar OM content compared with hollow tines and hollow tines 2X + hollow needle tines 2X. Green-dyed sand showed a higher percent green cover and DGCI compared with 90:10 sand:peat. Using hollow tines only or alternating them with hollow needle tines is the best option to decrease OM content while increasing Ksat in hybrid bermudagrass greens; however, their use could result in slower turfgrass recovery compared with other aerification methods.

Autonomous Compared with Conventional Mower Use on St. Augustinegrass Lawn Quality

Autonomous (i.e., robotic) mowers have recently garnered interest with the public and within the turfgrass industry. However, limited research has been conducted on their use for mowing warm-season turfgrasses. An experiment was conducted at the University of Florida’s West Florida Research and Education Center (Jay, FL, USA) to investigate the performance of an autonomous mower using a lower than recommended height-of-cut on St. Augustinegrass (Stenotaphrum secundatum). Treatments included an autonomous mower with a height-of-cut of 2.5 inches set to mow daily and a conventional mulching mower with weekly mowing at recommended height-of-cut of 3.5 inches. Data collection included weekly digital images that were subjected to digital image analysis to determine overall turfgrass quality, percent green cover, and uniformity. The autonomous mower resulted in greater overall turfgrass quality from January to March and in November, and greater green cover from November to April compared with conventional mowing. Additionally, the autonomous mower produced greater turfgrass uniformity than conventional mowing. Results indicate that autonomous mowers can be successfully used to maintain St. Augustinegrass at a lower than recommended height-of-cut.

Greening residential quarters in China: What are the roles of urban form, socioeconomic factors, and biophysical context?

Residential greenspace has great intracity variations. Its driving factors have been widely investigated in Western countries (e.g., in Europe and North America), where residential areas are mostly privately owned, but few studies have examined the determinants of residential greenspace in China, where land is owned by the government. Taking the subtropical city of Changsha, China, as an example, this study mapped the percent green cover (PGC) in residential quarters with a fine-resolution satellite image. We also investigated its driving factors measured from multisource geospatial data. The results show that (1) the PGC in the residential quarters showed great spatial variation, with an average of 36.6% (0–85.7%) and a standard deviation of 18.3%. (2) Urban form, biophysical context, and socioeconomic factors together explained 49.18% of the variation in the PGC, and they independently explained 22.87%, 11.17%, and 2.31% of the variation, respectively. (3) Residential quarter size, PGC in the surrounding buffer zone, residential quarter age, housing value, and population density significantly and positively impact the PGC, while percent building cover, floor area ratio, and distance to city center had significant negative impacts. The strongest positive and negative impacts came from PGC in the surrounding buffer zone and percent building cover, respectively. Socioeconomic factors, the dominant driving factors in Western countries, show little impact on residential PGC. These findings expand our understanding of the intracity variation in greenspace coverage and the driving factors, which sheds light on the effective planning and management of urban greenspaces in China.

Leaf, Root, and Crown Tissue Physiology of Annual Bluegrass after Cold Acclimation at Varying Soil Moisture Levels and Ice Encasement

Annual bluegrass (Poa annua) is a turfgrass species prone to winterkill-induced damage such as from ice encasement stress. This research aimed to determine whether different levels of soil volumetric water content (SWC) influence cold acclimation and recovery from ice encasement. Annual bluegrass was exposed to 8%, 12%, and 20% SWC treatments during cold acclimation in growth chambers. After cold acclimation, plants were subjected to ice encasement by misting at –3 °C until a 2.5-cm ice layer was formed. On 0 (no ice encasement exposure), 40, and 80 days of treatment, plants were analyzed for recovery (percent green canopy cover over time), and leaf, crown, and root tissues were harvested for lipid peroxidation and total nonstructural carbohydrates (TNC) including storage carbohydrates and water-soluble carbohydrates (WSC). Low SWC during cold acclimation enhanced recovery from cold temperatures and ice encasement. Root carbohydrates were influenced by SWC regimes during cold acclimation since day 0 plant roots exposed to the 8% SWC treatment had 143.9% higher TNC and 137.6% higher WSC compared with day 0 plants exposed to 12% and 20% SWC. Root levels of carbohydrates and lipid peroxidation were least influenced by cold and ice encasement among the organs evaluated. Prolonged freezing conditions and ice encasement reduced leaf and crown tissue carbohydrates and increased lipid peroxidation compared with day 0 plants not exposed to freezing temperatures and ice encasement. After 40 days of ice encasement, plants exposed to the 8% SWC treatment recovered faster than plants cold acclimated at higher soil moisture levels. Average percent canopy cover after 36 days of recovery in the greenhouse was 71.9% higher for 8% SWC treated plants than in 12% and 20% SWC treated plants. Turfgrass managers may benefit from annual bluegrass putting green management strategies to reduce fall soil moisture. Given that soil moisture did not significantly influence carbohydrate or lipid peroxidation results, except for in roots, additional research is needed to understand the mechanism associated with these findings.

Evaluation of Hollow-tine Core Aerification Recycling on a Sand-based Putting Green Soil Properties and Playability

Aeration and sand topdressing are important cultural practices for organic matter management on golf course putting greens. Many golf courses lack the budget for applications of new sand topdressing material. A 2-year study was conducted to investigate the effect of recycling sand from hollow-tine aerification cores on a sand-based creeping bentgrass (Agrostis stolonifera) putting green soil properties and playability. Treatments included traditional [T (cores removed and sand topdressed)], verticut [V (cores broken up with verticutter)], and recycle [R (cores recycled using a core recycler)]. There were no differences in root zone organic matter, bulk density, soil porosity, infiltration rates, percent sand recovered during mowing, surface firmness, and ball roll distance between treatments during the study. Immediately after aerification treatments, T had the highest percent green cover (PGC) (38.3%) compared with V (26.9%) and R (26.8%), indicating that T offered the least sand present on the surface. Seven days after treatments, there was no difference in PGC (85.3% to 90.1%), indicating all treatments recovered similarly. Alternative aerification treatments V and R could be useful techniques to minimize or reduce the amount of sand used for backfilling core aeration holes without compromising the putting green soil properties and playability.

Genetic variability and QTL mapping of winter survivability and leaf firing in African bermudagrass

AbstractTurf‐type bermudagrass is susceptible to winterkill when grown in transition zone climates. Minimizing water use in turfgrass management is of societal significance. African bermudagrass (Cynodon transvaalensis Burtt‐Davy) has been extensively used to cross with common bermudagrass (C. dactylon Pers. var. dactylon) in the creation of F1 hybrid cultivars. Little information regarding the molecular basis of winter survivability and drought resistance in African bermudagrass is available. Accordingly, the objectives of this study were to quantify genetic variability and identify quantitative trait loci (QTL) associated with winter survivability traits (spring greenup, SG; spring greenup percent green cover, SGPGC; winterkill, WK), and leaf firing (LF) in African bermudagrass. A total of 109 first‐generation self‐pollinated (S1) progeny of ‘OKC1163’ were evaluated in a field trial in a randomized complete block design with three replications for four seasons. Significant genetic variation existed for all the traits examined, and the broad‐sense heritability estimates ranged from .36 to .54 for the winter survivability traits and .80 for LF. Ten QTL were identified for winter survivability traits and two for LF based on a preexisting high‐density linkage map, which was aligned, reoriented, and renamed as to a recently published reference genome. Seven of 12 QTL were consistently identified at least in 2 yr. The colocation of two QTL, one for winter survivability and another for LF, suggests the possibility of improving both traits together. Findings provide new insights to genetic control of winter survivability traits and LF and contribute genetic resources for marker‐assisted selection in turf‐type bermudagrass improvement.

Comparing Smart Irrigation Controllers for Turfgrass Landscapes

Recent advances in irrigation technologies have led many states to incentivize homeowners to purchase United States Environmental Protection Agency WaterSense-labeled, smart irrigation controllers. However, previous research of smart controllers has shown that their use may still result in excess water application when compared with controllers manually programmed to replace actual water loss. This study compared kentucky bluegrass (Poa pratensis) irrigation applications using three smart irrigation controllers, a conventional irrigation controller programmed according to Cooperative Extension recommendations, and the average irrigation rate of area homeowners in Utah during 2018 and 2019. Of all the controllers tested, the manually programmed controller applied water at amounts closest to the actual evapotranspiration rates; however, smart controllers applied from 30% to 63% less water than area homeowners, depending on the controller and year of the study. Kentucky bluegrass health and quality indicators—percent green cover and normalized difference vegetation indices—varied between years of the study and were lower than acceptable levels on several occasions in 2019 for three of the four controllers tested. Compared with the results of similar studies, these findings suggest that the effects of smart irrigation controllers on turfgrass health and quality may vary by location and over time.

A Case study of Urban Heat Island and Air Pollution Mechanism in Bengaluru Metropolitan city

The industrialization in urban areas includes the economical increment, growth of GDPA, youth empowerment. The effects of industrialisation results in air pollution, sewage disposal, decline in green cover percentage. Urbanization or growth of city and Industrialization are embedded with one to another, without improving of Industrial sector, the growth of country cannot progress, but rapid industrialization and urbanization of metropolitan is cities of our country leads to generate huge environmental problems. This paper aims to determine and explore the relation with industrialization with Urban Heat Island (UHI). UHI is a phenomenon of accumulation of more temperature than rural areas. The metropolitan cities like Delhi, Mumbai, Ahmadabad, Kolkata, Bengaluru etc. These are the cities grown rapidly in present scenario. The mechanism of UHI, implications of it is in these metropolitan cities are overview of this research work. It includes collection, analysis of data related to UHI. Finally, it reveals the effect of UHI in different metropolitan cities. Increase in solid waste generation, air quality alteration, loss of aquatic life, air pollution, rise of skin diseases, asthma, respiratory problem etc. The objective of this paper is to understand the mechanism of the UHI process and its implications in different metropolitan cities by analyzing with parameter like raise in city temperature, thermal discomfort, pollution level, uneven rainfall, and increase in flood level.

QTL mapping of morphological characteristics that correlated to drought tolerance in St. Augustinegrass.

St. Augustinegrass is a warm-season grass species widely utilized as turf in the southeastern U.S. It shows significant variation in plant growth and morphological characteristics, some of which are potentially associated with drought tolerance. However, the genetic basis of these variations is not well understood. Detecting quantitative trait loci (QTL) associated with morphological traits will provide a foundation for the application of genetic and molecular breeding in St. Augustinegrass. In this study, we report QTL associated with morphological traits, including leaf blade width (LW), leaf blade length (LL), canopy density (CD), and shoot growth orientation (SGO) in a St. Augustinegrass ‘Raleigh’ x ‘Seville’ mapping population containing 115 F1 hybrids. Phenotypic data were collected from one greenhouse and two field trials. Single and joint trial analyses were performed, finding significant phenotypic variance among the hybrids for all traits. Interval mapping (IM) and multiple QTL method (MQM) analysis detected seven QTL for CD, four for LL, five for LW, and two for SGO, which were distributed on linkage groups RLG1, RLG9, SLG3, SLG7, SLG8 and SLG9. In addition, three genomic regions where QTL colocalized were identified on Raleigh LG1 and Seville LG3. One genomic region on Seville LG3 overlapped with two previously reported drought-related QTL for leaf relative water content (RWC) and percent green cover (GC). Several candidate genes related to plant development and drought stress response were identified within QTL intervals. The QTL identified in this study represent a first step in identifying genes controlling morphological traits that might accelerate progress in selection of St. Augustinegrass lines with lower water usage.

Evaluation of Compost and Soil Mix Ratios for Perennial Ryegrass Establishment on Topsoil and Subsoil

Soil degradation during construction often results in soil loss through erosion and reduced vegetation establishment. Composted organic materials are used to restore soil health of compromised urban soils when planting trees and shrubs; however, less is known about compost amendments for turfgrass establishment. The objective of this trial was to determine the effects of differing compost incorporation rates in two soil types on perennial ryegrass [PR (Lolium perenne)] establishment. The hypothesis was that as compost incorporation rates increase, turfgrass germination would increase until the compost rate becomes detrimental to turfgrass germination because of increased nitrate content and electrical conductivity (EC) levels. A salt-sensitive PR cultivar and a salt-tolerant PR cultivar were seeded into a loam topsoil and a clay subsoil at soil:compost volume ratios of 100:0, 80:20, 70:30, 60:40, 50:50, 40:60, and 0:100 using a mixed-source mature compost. Percent green cover (PGC) and leachate pH, EC, and nitrate content were measured during the 5-week establishment period. This trial showed that with a suitable topsoil, compost incorporation may be unnecessary to obtain acceptable PGC, but that compost additions (30% to 40%) to a clay subsoil achieve faster establishment while limiting the potential for reduced establishment because of increased nitrate content or EC associated with greater levels of compost incorporation. The EC or pH of soil:compost leachate was not found to predict turfgrass establishment. This trial suggests that soil type should be considered when making compost use rate recommendations; however, further research is needed to link compost physiochemical properties to compost use rates.