Search

Abstract Background Poa pratensis is a predominant cool-season turfgrass utilized in urban landscaping and ecological management. It is extensively employed in turf construction and in the regulation of ecological environments. However, it is susceptible to powdery mildew, a prevalent disease in humid regions. Currently, the primary control measure for powdery mildew involves the application of pesticides, a practice that is both costly and environmentally detrimental. Developing superior disease-resistant cultivars represents a more cost-effective and sustainable strategy for managing turfgrass diseases. Furthermore, an in-depth investigation into the response mechanisms of P. pratensis to powdery mildew infection could significantly advance research on the identification of disease resistance genes and the molecular breeding of resistant varieties. Results In this study, we first assessed the disease incidence across various disease-resistant P. pratensis cultivars and subsequently examined alterations in their in vivo redox states. We employed isobaric tags for relative and absolute quantification (iTRAQ) proteomics alongside non-targeted metabolomics to elucidate the response mechanisms of P. pratensis to powdery mildew invasion. A comprehensive analysis of the shared KEGG pathways among differentially abundant proteins (DAPs) and differentially enriched metabolites (DEMs) led to the identification of four common KEGG pathways. Notably, the phenylpropanoid biosynthesis pathway, enriched in both examined P. pratensis cultivars, was selected for further investigation. This analysis indicated that lignin biosynthesis plays a crucial role in the response of P. pratensis to powdery mildew infection. Conclusions The findings of this study enhance our understanding of the mechanisms underlying powdery mildew resistance in P. pratensis and serve as a valuable reference for the selection of powdery mildew-resistant cultivars, as well as for the identification and application of associated disease resistance genes. Clinical trial number Not applicable.

Soil Cd pollution is a significant environmental issue faced by contemporary society. Kentucky bluegrass is considered a potential phytoremediation species, as some varieties have excellent cadmium (Cd) tolerance. However, the mechanisms of Cd accumulation and transportation in Kentucky bluegrass are still not fully understood. The Cd-tolerant Kentucky bluegrass cultivar ‘Midnight’ (M) exhibits lower Cd translocation efficiency and a higher leaf Cd concentration compared to the Cd-sensitive cultivar ‘Rugby II’ (R). We hypothesized that Cd translocation from roots to shoots in cultivar M is hindered by the endodermal barriers and cell wall polysaccharides; hence, we conducted Cd distribution, cytological observation, cell wall component, and transcriptomic analyses under Cd stress conditions using the M and R cultivars. Cd stress resulted in the thickening of the endodermis and increased synthesis of cell wall polysaccharides in both the M and R cultivars. Endodermis development restricted the radical transport of Cd from the root cortex to the stele, while the accumulation of cell wall polysaccharides promoted the binding of Cd to the cell wall. These changes further inhibited the long-distance translocation of Cd from the roots to the aerial parts. Furthermore, the M cultivar exhibited limited long-distance Cd translocation efficiency compared to the R cultivar, which was attributed to the enhanced development of endodermal barriers and increased Cd binding by cell wall polysaccharides. This study provides valuable insights for screening high Cd transport efficiency in Kentucky bluegrass based on anatomical structure and genetic modification.

Kentucky bluegrass (Poa pratensis L.) is a valuable cool-season turfgrass widely utilized for forage, turf, and ecological purposes; however, its productivity and ornamental value are significantly compromised by powdery mildew, caused by Blumeria graminis f. sp. Poae, which negatively affects turf quality. In the present study, we examined the interactions between P. pratensis varieties and B. graminis, focusing on primary haustorium formation at 24 h post-inoculation and the formation of germ tubes at 48 h post-inoculation. We explored the molecular mechanisms underlying the response of different P. pratensis varieties at 48 h post-inoculation via transcriptomic techniques. Our results revealed that the primary haustorium formation rate in ‘Taihang’ at 24 h after B. graminis inoculation was significantly lower than that in ‘Explorer’ and ‘Black Jack’. The conidia of B. graminis could form two to five germ tubes, and the proportion of conidia that formed five germ tubes in ‘Taihang‘ at 48 h post-inoculation was significantly lower than that in the other two varieties. Transcriptome analysis revealed 680,765 transcripts as unigenes. A total of 9983 unigenes were identified as differentially expressed genes in one or more varieties of P. pratensis after inoculation with powdery mildew compared with the control. In total, 6284 differentially expressed genes were upregulated in ‘Taihang’, which was substantially greater than those in ‘Black Jack’ (4530) and ‘Explorer’ (4666). Moreover, 2843 differentially expressed genes were specific to ‘Taihang’, whereas 1644 and 1590 unique differentially expressed genes were specific to ‘Explorer’ and ‘Black Jack’, respectively. The specifically expressed genes play crucial roles in determining the disease resistance of powdery mildew. Notably, the expression of genes encoding chitinase, gamma-glutamyltranspeptidase 1, UDP-arabinopyranose mutase 1, oxalate oxidase 2, mitogen-activated protein kinase kinase 1-like, tryptophan decarboxylase, and aromatic L-amino acid decarboxylase was closely related to powdery mildew resistance in ‘Taihang’, making them promising candidate genes for studying resistance to powdery mildew in P. pratensis. This study identified critical genes involved in powdery mildew resistance in P. pratensis, providing a basis for future gene mining and molecular breeding to increase disease resistance in P. pratensis.

Plant and soil C:N:P stoichiometry reflects the element content and energy flow, which are important for biogeochemical cycling in ecosystems. Although plantation age has been verified to affect leaf C:N:P stoichiometry in alfalfa plants, its effect on plant and soil C:N:P stoichiometry in grass remains poorly documented. A 10-year field experiment of Kentucky bluegrass (Poa pratensis) was used to test how plantation age affect plant and soil C:N:P stoichiometry in a perennial rhizomatous grass pasture. This study demonstrated that leaf C:N, C:P, and N:P ratios exhibited a rapid increasing trend from 2 to 6 years of age, whereas leaf C:N showed a slight decreasing trend, and leaf C:P and N:P maintained stability from 6 to 9 years of age. Stem C:N and N:P were not different among plantation ages, while stem C:P increased from 2 to 4 years of plantation age and then maintained stability from 4 to 9 years of plantation age. Root N:P showed an increasing trend from 2 to 6 years of plantation age and relative stability from 6 to 9 years of plantation age, whereas root C:N and C:P showed decreasing trends from 2 to 9 years of plantation age. Although soil C:P did not differ among nine plantation ages, soil C:N and N:P remained relatively stable from 2 to 6 years of plantation age. However, soil C:N showed a decreasing trend, while soil N:P showed an increasing trend after 6 years of plantation age. The results from an ecological stoichiometric homeostasis analysis further showed that N in the leaf, stem, and root and P in the stem had strict homeostasis, whereas P in the leaf and root showed plastic and weakly homeostatic status, respectively. These results present a pattern concerning the plantation age in relation to plant and soil C:N:P stoichiometry in a perennial grass and provide useful information for N and P management in Kentucky bluegrass pastures.

Native fescue grassland degradation and reductions in plant species diversity due to smooth brome (Bromus inermis Leyss.) invasion and dominance have far ranging consequences for both human and ecological systems. A study was undertaken to reduce smooth brome which was invading foothills fescue grassland in Canada and displacing native species. Sheep and cattle grazing, mowing, glyphosate, and burning were applied to control smooth brome-dominant grasslands over three growing seasons. Defoliation (5 to 10 cm, 2 to 4 times) did not reduce smooth brome tiller density, etiolated regrowth, or total non-structural carbohydrates; however, the three heaviest defoliation treatments (sheep 3×, cattle 3×, mowing 4×) reduced smooth brome composition by year 3. Repeated glyphosate wicking (1× year 1, 2× year 2) was the most effective treatment and reduced smooth brome tiller density by 50% by year 3. Early-spring burning, as smooth brome began to grow, stressed the plants and reduced tiller density. Kentucky bluegrass (Poa pratensis L.), the subdominant species, increased in all treatments except the reference; thus, reducing smooth brome may result in another undesirable species becoming dominant.

IntroductionEvaluation of the effects of water-limited conditions on the photosynthetic characteristics and forage yield is important for enhancing the forage productivity and drought tolerance in Kentucky bluegrass (Poa pratensis L.).MethodsIn the present study, 100 P. pratensis ecotypes collected from different geographical areas in Iran were assessed under well-watered and drought stress conditions. Genetic variation and response to selection for the photosynthetic characteristics [i.e., net photosynthesis rate (A), stomatal conductance (gs), transpiration rate (Tr), chlorophyll content (Chl), and photochemical efficiency (Fv/Fm)] and forage yield [fresh forage yield (FY) and dry forage yield (Dy)] traits were analyzed during the 2018 and 2019 growing seasons.Results and discussionDrought stress had negative effects on evaluated photosynthesis parameters and significantly reduced dry and fresh forage yields. On average, FY with a 45% decrease and gs with a 326% decrease under drought stress conditions showed the highest reduction rate among forage yield and photosynthesis traits, respectively. Genotypic coefficients of variation (GCV) for FY were lower under drought stress. The estimates of heritability, genetic advance, and genetic advance as percentage of mean showed the predominance of additive gene action for the traits. Overall, the results showed that “Ciakhor”, “Damavand”, “Karvandan”, “Basmenj”, “Abr2”, “Abrumand”, “Borhan”, “Hezarkanian”, “LasemCheshmeh”, “Torshab”, and “DoSar” have higher forage yield production with little change between two irrigation regimes, which makes them promising candidates for developing high-yielding drought-tolerant varieties through breeding programs.

Abstract Background Rhizome is vital for carbon and nitrogen metabolism of the whole plant. However, the effect of carbon and nitrogen in the rhizome on rhizome expansion remains unclear. Results Three wild Kentucky bluegrass (Poa pratensis L.) germplasms with different rhizome expansion capacity (strong expansion capacity, ‘YZ’; medium expansion capacity, ‘WY’; and weak expansion capacity, ‘AD’) were planted in the field and the rhizomes number, tiller number, rhizome dry weight, physiological indicators and enzyme activity associated carbon and nitrogen metabolisms were measured. Liquid chromatography coupled to mass spectrometry (LC-MS) was utilized to analyze the metabolomic of the rhizomes. The results showed that the rhizome and tiller numbers of the YZ were 3.26 and 2.69-fold of that of the AD, respectively. The aboveground dry weight of the YZ was the greatest among all three germplasms. Contents of soluble sugar, starch, sucrose, NO3 −-N, and free amino acid were significantly higher in rhizomes of the YZ than those of the WY and AD (P

Golf facilities account for 2.3 million acres in the United States. Numerous turfgrass species are managed on US golf facilities, but golf facilities may change turfgrasses depending on numerous variables. Knowing which turfgrasses are grown and how turfgrass selection has changed would provide important information to scientists, turfgrass managers, and policymakers. The objective of this survey was to measure turfgrass use on US golf facilities in 2021 and to determine whether changes in turfgrass selection have occurred since 2005. A survey was developed and distributed via e-mail to 13,938 US golf facilities, with 1861 responding. From 2005 to 2021, the total projected area of maintained turfgrass on US golf facilities decreased by 14.2%, which was likely a result of course closures and maintenance operations. Nationally, bermudagrass (Cynodon sp.) and Kentucky bluegrass (Poa pratensis) remained the most common warm- and cool-season turfgrasses, respectively. The area of winter-overseeded turfgrass declined by 60% between 2005 and 2021. The percentage of golf facilities that used zoysiagrass (Zoysia sp.) and seashore paspalum (Paspalum vaginatum) increased depending on region and specific playing surface, albeit a pragmatically minor increase. In general, turfgrass selection on golf facilities in northern climates did not change, whereas turfgrass selection in southern climates favored a change from cool- to warm-season species, depending on the playing surface. Whether in historically cool-season or warm-season regions, it appears that many golf facilities are exploring alternatives to their traditional turfgrass species.

A cutting trial was conducted to determine the nutritional value, crude protein (CP) fractions distribution and CP ruminal degradability of white clover (Trifolium repens L.) and Kentucky bluegrass (Poa pratensis L.) as the dominant species of permanent grassland. The legume and grass herbage was obtained in the field experiment carried out on pasture throughout a spring growth season where rotational grazing was simulated using three consecutive cuts, which were compared. The fractionation of CP, according to Cornell Net Carbohydrate and Protein System (CNCPS v6.5), was used to predict protein degradability of the legume and grass forage. A significant (p

Kentucky bluegrass (Poa pratensis L.) is an important cool season turfgrass species with a high cold tolerance, but it is sensitive to drought. It is valuable for the applications of Kentucky bluegrass to improve its drought tolerance. However, little is known about the underlying drought mechanism. In the present study, transcriptomic profiling in the roots and leaves of the Kentucky bluegrass cultivar ‘Qinghai’, in response to osmotic stress in the form of treatment with 2 h and 50 h of 25% (v/v) PEG-6000, was analyzed. The results showed that a large number of genes were significantly up-regulated or down-regulated under osmotic stress. The majority of genes were up-regulated in leaves but down-regulated in roots after 2 h and 50 h of osmotic stress, among them were 350 up-regulated DEGs and 20 down-regulated DEGs shared in both leaves and roots. GO and KEGG analysis showed that carbohydrate metabolism, polyamine and amino acid metabolism and the plant hormone signaling pathway were enriched in the leaves and roots of ‘Qinghai’ after osmotic stress. The genes involving in carbohydrate metabolism were up-regulated, and sucrose, trehalose and raffinose levels were consistently increased. The genes involved in polyamine and amino acid metabolism were up-regulated in leaves in response to osmotic stress and several amino acids, such as Glu, Met and Val levels were increased, while the genes involved in photosynthesis, carbon fixation and citrate cycle in leaves were down-regulated. In addition, the genes involved in plant hormone biosynthesis and signal transduction were altered in leaves after osmotic stress. This study provided promising candidate genes for studying drought mechanisms in ‘Qinghai’ and improving the drought tolerance of Kentucky bluegrass and drought-sensitive crops.

The application of phytohormones is a viable technique to increase the efficiency of phytoremediation in heavy metal-contaminated soils. The objective of this study was to determine how the application of 24-epibrassinolide (EBR), a brassinosteroid analog, could regulate root growth and tolerance to cadmium (Cd) stress in Kentucky bluegrass. As a result, the number of lateral root primordia and total root length in the Cd-treated seedlings decreased by 33.1 % and 56.5 %, respectively. After the application of EBR, Cd accumulation in roots and leaves, and the negative effect of Cd on root growth were reduced under Cd stress. Additionally, the expression of the brassinosteroid signaling gene PpBRI1 was significantly upregulated by exogenous EBR. Moreover, exogenous EBR upregulated the expression of genes encoding antioxidant enzymes and improved the activity of antioxidant enzymes, thereby reduced oxidative stress in roots. Finally, targeted hormonomics analysis highlighted the utility of the application of EBR to alleviate the effect of Cd on the reduction in auxin (IAA) content and the increase in ethylene (ACC) content. These were known to be associated with the upregulation in the expression of auxin biosynthesis gene PpYUCCA1 and downregulation in the expression of ethylene biosynthesis gene PpACO1 in the roots treated with Cd stress. Overall, the application of EBR alleviated Cd-induced oxidative stress in addition to improving root elongation and lateral root growth crosstalk with auxin and ethylene in Kentucky bluegrass subjected to Cd stress. This study further highlights the potential role of brassinosteroids in improving the efficiency of phytoremediation for Cd-contaminated soils.

Ecologists consider biological invasions one of the primary drivers of global change. Many remaining grasslands in North America have extensive invasions of exotic grass species that have replaced native plant species. In the Northern Great Plains, exotic cool-season grasses Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus inermis), paired with human alterations to the landscape and historical disturbance regimes, have resulted in functionally and structurally altered grassland plant communities. These changes may extend to impact species that rely on these plant communities, such as bees. Bees are ecologically diverse and serve important pollinator roles but are at risk from the loss and change of floral and nesting resources in plant communities. Our objectives were to determine whether Kentucky bluegrass and smooth brome alter the bee and forb species richness in invaded Northern Great Plains grasslands and how litter accumulation, grass cover, the amount of bare ground, and forb species richness interact with bee functional traits. To do this, we surveyed 67 grassland sites from 2017 to 2020 with two bee-sampling methods (268 netting and bee bowl surveys total) and vegetation cover surveys at each site. We collected 20,559 bees from 201 bee species and observed 249 forb and shrub species in vegetation surveys. Bee richness and Shannon diversity were associated with greater forb richness while forb richness was significantly lower with thicker litter depths and higher with a greater coverage of all grasses other than Kentucky bluegrass and smooth brome. Bee trait analyses showed varying relationships with plant community variables. Of these, litter depth and Kentucky bluegrass cover were associated with lower ground-nesting bee abundance while small-bodied bee abundance was positively associated with increasing bare ground. While our results support the close relationship between bee and plant diversity, we also found litter depth, in particular, contributed to the structure of these two communities. Specifically, Kentucky bluegrass and smooth brome are two exotic grass species associated with thatch-forming litter layers, especially under idle management that appear to simplify bee and forb communities. Our results make apparent the importance in maintaining structural and compositional diversity in invaded grasslands to support diverse bee communities.

Rhizome growth and development is regulated by phytohormone. However, endogenous phytohormones affect rhizome initiation, and sustained growth in perennial grass species remains elusive. In this study, we investigated the morphological characteristics and the content of indole-3-acetic acid (IAA), zeatin (ZT), gibberellic acid (GA3), and abscisic acid (ABA) in the rhizomes of two different Kentucky bluegrass. Using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS), we performed metabolite analysis of two different rhizomes. In our study, the multi-rhizome Kentucky bluegrass material ‘Yuzhong’ had an average of 1113 rhizomes, while the few-rhizome material ‘Anding’ had an average of 347 rhizomes. The diameter of rhizome and length of rhizome internode in ‘Yuzhong’ were 1.68-fold and 1.33-fold higher than that of the ‘Anding’, respectively. The rhizome dry weight of ‘Yuzhong’ was 75.06 g, while the ‘Anding’ was 20.79 g. ‘Yuzhong’ had a higher ZT content (5.50 μg·g−1), which is 2.4-fold that of ‘Anding’ (2.27 μg·g−1). In contrast, the IAA, ABA, and GA3 content of rhizome were markedly higher in ‘Anding’ than ‘Yuzhong’. Correlation analysis revealed significant correlations between ZT and ZT/ABA with the number of rhizomes, diameter of rhizome, and length of rhizome internode, whereas IAA, ABA, GA3, and IAA/ZT were opposite. In the metabolic profiles, we identified 163 differentially expressed metabolites (DEMs) (60 upregulated and 103 downregulated) in positive ion mode and 75 DEMs (36 upregulated and 39 downregulated) in negative ion mode. Histidine metabolism and ABC transporters pathways were the most significantly enriched in the positive and negative ion mode, respectively, both of which are involved in the synthesis and transport of cytokinin. These results indicate that cytokinin is crucial for rhizome development and promotes rhizome germination and growth of Kentucky bluegrass.

In this study, the issue of irrigation of a mixture of white clover (Trifolium repens L.) and kentucky bluegrass (Poa pratensis L.) plants with different concentrations of the effluent of Van Edremit Advanced Biological Wastewater Treatment Plant in Turkey is discussed. In this context, the research was carried out to investigate the effect of wastewater on the growth of plants sole and in mixtures. In addition, it was aimed to determine the short-term effects of wastewater on some metal and metalloid content in soil and plants. The experiment was carried out in three replications according to the randomized plots trial design in pots in the climate room in 2018. Applications in the study were 100% pure water control (100S), 25% wastewater + 75% pure water (25A75S), 50% wastewater + 50% pure water (50A50S) and 75% wastewater + 25% pure water (75A25S). The plant height of the plants increased depending on the amount of wastewater application in all forms. The highest average plant height of 10.70 cm was obtained from 75A25S in white clover, and 11.42 cm and 11.21 cm in kentucky bluegrass from control and 75A25S applications, respectively. The fresh and dry weight of white clover increased depending on wastewater applications, but the effect of wastewater applications was not observed in kentucky bluegrass. The metal and metalloid content of plants and post-harvest soil generally increased depending on the applications. The metal and metalloid contents, except molybdenum (Mo) in the kentucky bluegrass and copper in the white clover, reached the highest values in the 75A25S application. There was no change in Mo, lead, and cadmium contents in the soil after harvest, but other metal and metalloid contents increased. It was determined that there was a decrease in pH value with wastewater applications in soil samples taken after harvest. It was determined that the electrical conductivity value of the soil increased as the wastewater application concentrations increased. In the light of these results, the positive effects of the wastewater used on plant growth and development were determined, but it was concluded that long-term studies are needed for its effects on the soil.

In 2020, a greenhouse experiment was conducted to investigate the suppression of annual bluegrass (Poa annua), which is a difficult weed to manage in cool-season in turfgrass mixtures on football pitches. The efficacy of prohexadione calcium (Pc), ethephon (Eth) and Pseudomonas fluorescens against P. annua, Lolium perenne and Poa pratensis was tested, as the latter two most commonly occur in turfgrass mixtures on football pitches. Mesotrione (Mes) was used as a positive control, and nontreated grass was used as a negative control. Only a single grass species was sown in each pot. Treatments were randomly distributed for two experiments conducted separately: first – unmown grass before the beginning of spraying and second – grass mowed before the beginning of spraying. In both experiments, plant height and the number of tillers were measured/counted several times during the growing season. In both experiments, grasses were sprayed six times with Pc, Eth and P. fluorescens, while Mes was applied twice. Based on the performed study, the efficacy of the tested products is connected to grass species and whether the grass was mowed/cut before spraying. It has been detected in the present study that spraying with Pc could reduce the height of annual bluegrass, while spraying with P. fluorescens has reduced the number of tillers. Spraying was more effective on grasses that were mowed/cut before the beginning of spraying. Mes should cause severe damage to annual bluegrass but without confirmation in this study. Results of this study have indicated that the application of Pc and P. fluorescens can inhibit the spread of annual bluegrass in football pitches; however, testing their effectiveness against P. annua under field conditions should be performed as well.

The durability of four grass living mulches, population of annual and perennial weeds, and their biodiversity in tree rows and tractor alleys were evaluated in the first 4 years after cover crop sowing. The experiment was established in a young semi-dwarf apple orchard 1 year after the planting of the tree ‘Chopin’ cv. Soil coverage was satisfactory for the three cover crops: red fescue, Kentucky bluegrass, and perennial ryegrass. The sods of the grasses exhibited 100% soil surface cover in the tree rows and drive alleys, starting from 1 year after sowing to the end of the study period. Only the maintenance of the blue fescue resulted in low average soil development. Annual and perennial weed populations were lower in the tree rows than in the drive alleys. It was determined meticulous and manual soil preparation prior to all grass sowing under tree crowns, followed by precise mowing of grasses and nitrogen fertilization in subsequent years. The highest soil surface cover by the total annual taxa was observed immediately after the emergence of the living mulch. Total perennial weed populations increased in the following vegetation seasons. Trifolium repens L. and Taraxacum offcinale (L.) Web. dominated all the grass living mulches evaluated. Only the red fescue sod effectively limited the infestation of perennial weed after 4 years of living mulch maintenance in the tree row. More than half of the annual and perennial weed taxa occurred sporadically in all living mulches. In both the tree rows and tractor alleys, the soil surface cover was not more than 1%, and these species contributed to the increase in orchard biodiversity.

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.

Consumers often have multiple choices when purchasing retail lawn products in stores. In this study, we evaluated the acute drought performance of locally available retail lawn seed products (mixtures or blends) at two mowing heights of 2.5 and 3 inches. We hypothesized that the species present in the products and the height-of-cut differentially influence the drought resistance and recovery of the mixtures and blends. In Fall 2016 and 2017, 28 different products consisting of 25 mixtures and 3 blends of turfgrass seeds were established under a fully automated rainout shelter at the St. Paul campus of the University of Minnesota. The drought treatments lasted for 67 days in 2017, and 52 days in 2018; both the 2017 and 2018 treatments were followed by a recovery period. Data were obtained during acute drought treatments and recovery periods for visual turfgrass quality and green turfgrass cover using digital images of the plots. During the first year, several products displayed higher green stability (or the ability to remain green) at the 3-inch height-of-cut compared with the 2.5-inch height-of-cut. Products with tall fescue (Schedonorus arundinaceus) and fine fescue (Festuca sp.) as dominant species generally performed better during the drought treatments, whereas an increasing presence of perennial ryegrass (Lolium perenne) and kentucky bluegrass (Poa pratensis) decreased the visual drought performance of the products. During the recovery period, an effect of the interaction between mowing height and the date of data collection on the percentage of green cover was observed: the lower mowing height improved the early recovery of green cover after acute drought. These findings suggest that consumers in the upper midwestern United States and areas with a climate similar climate to that of St. Paul, MN, who are challenged with multiple choices of lawn seed products should choose products containing a higher tall fescue content and adjust their mowing heights to optimize recovery.

Fine fescues (Festuca spp.) and tall fescue (Schedonorus arundinaceus) are low-input turfgrass species that perform well under less water, pesticides, and fertilizers when compared to commonly cultivated species in the Midwestern US. There are numerous benefits in increasing the use of low-input turfgrasses: lowering resource usage, reducing maintenance costs, improving the landscape aesthetic, and contributing to residents’ health and general wellbeing. However, increasing the market share of these grasses requires an understanding of what influences buyers to purchase these turfgrasses. These grasses are usually purchased by consumers as seed; however, sod is a preferred method of establishment for many professional end users. To better understand the economic potential of low-input turfgrass sod, we surveyed sod buyers (landscapers, golf courses, sports turf managers) who purchased sod in 2020 to investigate (1) the factors impacting them to purchase low-input turfgrasses, and (2) the factors influencing the quantity purchased of low-input turfgrasses. The results from our model showed that larger businesses are the most likely to purchase low-input turfgrasses, and, once they purchase them, they tend to acquire a larger amount than their smaller counterparts. Landscaping businesses were more likely to purchase low-input turfgrasses, and factors such as availability, distance, drought, and shade tolerance impacted the decision to purchase low-input turfgrasses. Finally, turfgrass density, the ability to purchase directly from the sod grower, and availability impacted the amount of turfgrasses that buyers purchased.

Plant growth regulators (PGRs) are widely used in turfgrass management. This study aimed to find the influence of different rates of PGRs on Kentucky bluegrass visual quality. Six PGRs were applied, Trinexapac Ethyl, Paclobutrazol, Flurprimidol, Mefluidide, Ethephon, and Gibberellic Acid. The measurement of the leaf color was performed using a spectrophotometer. The turfgrass visual quality was judged using a visual rating system. Trinexapac Ethyl and Flurprimidol applications improved the overall appearance of turfgrass. Paclobutrazol and Gibberellic Acid decreased the overall appearance of investigated Kentucky bluegrass cultivars. The leaf texture assessment was only improved by Gibberellic Acid. The color assessment was enhanced with Paclobutrazol but deteriorated with Gibberellic Acid. PGRs affected the wavelength in a range of 520 to 630 nm. Gibberellic Acid caused lighter leaves with higher green and yellow hues. Paclobutrazol caused darker leaves with a lower green and a reddish hue. Trinexapac Ethyl application resulted in a more reddish hue. PGR rates also affected the visual quality of Kentucky bluegrass turfgrass.

Kentucky bluegrass (Poa pratensis L.) is a cool-season turfgrass species that responds strongly to nitrogen (N), but the metabolomic responses of this grass species to N supply is unknown. The N-tolerant cultivar Bluemoon and N-sensitive cultivar Balin were exposed to normal N (15 mM) and low N (0.5 mM) for 21 days for identification of differentially expressed metabolites (DEMs) between normal N and low N treatments. Balin had more reductions of chlorophyll and total soluble protein concentrations and a higher accumulation of superoxide radicals under low N stress. A total of 99 known DEMs were identified in either cultivar or both including 22 amino acids and derivatives, 16 carbohydrates, 29 organic acids, and 32 other metabolites. In Bluemoon, β-alanine metabolism was most enriched, followed by alanine, aspartate, and glutamate metabolism, biosynthesis of valine, leucine, and isoleucine biosynthesis, and glycine, serine, and threonine metabolism. In Balin, alanine, aspartate, and glutamate metabolism were most enriched, followed by the tricarboxylic acid (TCA), glyoxylate and decarbohydrate metabolism, and carbon fixation. Bluemoon generally maintained higher TCA cycle capacity and had more downregulated amino acids, while changes in more organic acids occurred in Balin under low N stress. Some metabolite changes by low-N stress were cultivar-specific. The results suggested that regulation of metabolites related to energy production or energy saving could contribute to low N tolerance in Kentucky bluegrass.

Understanding the effect of water heterogeneity on the growth and water integration of clonal plants is important for scientific water management. In controlled field plots, we conducted a study by creating three different soil water treatments comprising four patches with different soil water supplies using Kentucky bluegrass (Poa pratensis L.) as the materials. The objective was to explore the differences in the growth indices and morphological attributes, and the possible water integration in ‘Arcadia’ Kentucky bluegrass in plots and patches with different soil water availabilities. Soil water deficit resulted in the declined biomass, root/shoot ratio and leaf relative water content of the whole genet, decreased leaf length and height of mother ramet, reduced leaf width and height of daughter ramets, and significant changes in the structures of vascular bundles in rhizomes and leaves. However, the leaf length, leaf width, height and leaf relative water content of daughter ramets in heterogeneous water-poor patches were recovered to the levels in water-rich patches. In addition, the diameter of the vessel in the xylem and percentage of the xylem area in leaf vascular bundles of daughter ramets in the heterogeneous water-poor patch were insignificantly different from those in water-rich patches. These results demonstrated that water integration among interconnected ramets promoted the growth status of daughter ramets in heterogeneous water-poor patches. However, the water translocation in interconnected ramets subjecting to heterogeneous water supplies was not investigated using stable isotope labelling in this study. Thus, the directions and patterns of water translocation among ramets necessitate further research.

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

Biochars are produced by low-oxygen gasification or pyrolysis of organic waste products, and can be co-produced with energy, achieving waste diversion and delivering a soil amendment that can improve agricultural yields. Although many studies have reported the agronomic benefits of biochars produced from pyrolysis, few have interrogated the ability of gasified biochars to improve crop productivity. An earlier study described the ability of a biochar that was derived from gasified Kentucky bluegrass (KB) seed screenings to impact the chemistry of acidic agricultural soils. However, that study did not measure the effects of the biochar amendment on plant growth or on nutrient acquisition. To quantify these effects we conducted a greenhouse study that evaluated wheat grown in agricultural soils amended with either the KB-based biochar or a biochar derived from a blend of woody mixed-waste. Our studies indicated that biochar amended soils promoted the growth of wheat in these agricultural alfisols. Our elemental analysis indicated that an attenuation of metal toxicity was likely responsible for the increased plant growth. The results of our study are placed in the context of our previous studies that characterized KB-sourced biochar and its effects on soil chemistry.

Non-irrigated crops in temperate and irrigated crops in arid regions are exposed to an incessant series of drought stress and re-watering. Hence, quick and efficient recuperation from drought stress may be amongst the key determinants of plant drought adjustment. Efficient nitrogen (N) nutrition has the capability to assuage water stress in crops by sustaining metabolic activities even at reduced tissue water potential. This study was designed to understand the potential of proper nutrition management by studying the morphological and physiological attributes, and assimilation of nitrogen in Kentucky bluegrass under drought stress. In present study, one heterogeneous habitat and four treatments homogenous habitats each with four replications were examined during field trial. Drought stress resulted in a significant reduction in the nitrogen content of both mother and first ramets, maximum radius, above and below ground mass, number of ramets per plot, leaf water contents and water potential and increased the carbon content and the C:N ratio in both homogenous and heterogeneous plots compared to well-watered and nutritional conditions. Observation using electron microscopy showed that drought stress shrunk the vessel diameter, circumference and xylem area, but increased the sieve diameter, and phloem area in the leaf crosscutting structure of Kentucky bluegrass, first, second, and third ramet leaf. Thus, it can be concluded that water stress markedly reduced all the important traits of Kentucky bluegrass, however, proper nutritional management treatment resulted in the best compensatory performance under drought assuaging its adversity up to some extent and may be considered in formulating good feasible and cost-effective practices for the environmental circumstances related to those of this study.

The state of mixed swards of red fescue, Kentucky bluegrass and bird's foot trefoil was studied. The experiment was situated along the slopes of the Central Balkan Mountain, during the period of the 1st to the 13th year of their creation. At a high degree of soil gleying, the low part of the slope, the dry matter yields were within the limits of 2.8 t/ha (1997, south-eastern exposure) up to 10.66 t/ha (1999, north-eastern exposure). At a low degree of soil gleying, high part of the slope, the dry matter yields were within the limits of 2.34 t/ha (1994, western exposure) up to 14.34 t/ha (1995, east exposure). The most prominent in productive terms for the period of the study are the variants at the east and south-eastern exposure, slightly gleyed soil. The participation of the sown species in the total forage yield is variable quantity. They reach (at their most) up to 96% in 1998, north exposure, slightly gleyed soils and up to 97% in 2000, north-east exposure, highly gleyed soils. Their share was small in 2004 (44%) and in 2006 (42%) on a western slope, highly eroded soils.

ABSTRACT Grasslands of the Northern Great Plains of North America are in the midst of extensive human‐driven loss and redistribution of important species. Invasive plants contribute to degradation of this ecosystem and present monumental challenges for natural resource managers. Widespread decreases in populations of grassland‐dependent wildlife, particularly birds, have been documented, but relatively little research has been focused on direct responses of wildlife to invading plants relative to native vegetation. Smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis) are 2 invasive cool‐season grass species found across much of the Northern Great Plains that continue to expand despite management actions intended to reduce them. With eradication unlikely, creativity, cooperation, and science‐based management (e.g., Adaptive Management) are paramount to protect and restore the integrity of grassland habitats across the Northern Great Plains. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Turfgrass species differ greatly in their ability to withstand the abrasion and compaction of traffic. Wear tolerance of turfgrass species and cultivars has been evaluated abroad by many researchers, while only few and partial studies have been conducted in Italy. Field experiment was carried out in Viterbo in 2001, 2002 and 2003 to evaluate the effect of the simulated traffic on 110 varieties belonging to four turfgrass cool-season species: tall fescue (Festuca arundinacea Schreb.), fine fescues (Festuca rubra L. ssp. rubra Gaud., ssp. commutata Gaud., ssp. tricophylla Gaud.), perennial ryegrass (Lolium perenne L.) and Kentucky bluegrass (Poa pratensis L.). Shoot density, visual turfgrass quality and thatch thickness were the major characters recorded to estimate wear tolerance. Traffic was simulated using a device containing three rollers pulled by a small tractor. The traffic simulator weighed 564 kg and applied a pressure of about 3 MPa. Results indicated that perennial ryegrass and tall fescue had high wear tolerance and low statistical variation among cultivars. Kentucky bluegrass showed an average wear tolerance owing to its shoot density and good recovery potential. In spite of their high shoot density, fine fescues exhibited poor wear tolerance because of their scarce resistance to high temperatures which are typical of the Mediterranean climate in late spring and summer. This study enabled a preliminary selection of the most suitable cool-season grasses and cultivars for trafficked and non-trafficked areas in Central Italy and highlighted that different turfgrass species have different wear tolerance mechanisms.