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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Nitric oxide (NO) induce tolerance to cadmium stress. • Nitric oxide induces antioxidant defense system and osmolytes accumulation. • Nitric oxide alleviate cadmium stress by regulating genes related to signal transduction, carbohydrate transport and metabolism, amino acid biosynthesis and phenylpropane biosynthesis. Cadmium (Cd) is harmful to the environment, as it is a non-essential biological element. It leads to the normal dysfunction and degradation of soil quality, and is toxic to plants. Many studies reported that the application of nitric oxide (NO) can effectively reduce the toxicity of Cd in plants. However, the underlying molecular mechanism of the positive effects of exogenous NO on plant Cd tolerance has not been well documented. In the present study, comparative transcriptome analysis was performed on Kentucky bluegrass seedlings treated with Cd (Cd alone) and Cd + NO (Cd and NO simultaneously).Comparative transcriptional regulation analysis showed that Differential expressed genes (DEGs) was mainly involved in mitogen-activated protein kinase (MAPK) signal transduction, plant hormone signal transduction, phenylpropanoid biosynthesis, amino acid transport and metabolism, fatty acid metabolism and biosynthesis related pathways. These results suggest that exogenous NO may alleviate cadmium stress by regulating genes related to signal transduction, carbohydrate transport and metabolism, amino acid biosynthesis and phenylpropane biosynthesis. Additionally, the DEGs and metabolic pathways between Cd and Cd + NO treatment groups were analyzed in this study, and a series of key genes mediated by NO signal in response to cadmium stress were screened out, and they were listed as candidate genes related to NO alleviating cadmium stress in Kentucky bluegrass. This study helps to understand the transcriptional regulation and complex internal network of exogenous NO alleviating Cd -tolerance in Kentucky bluegrass. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

Poa pratensis, commonly known as Kentucky bluegrass, is a popular cool-season grass species used as turf in lawns and recreation areas globally. Despite its substantial economic value, a reference genome had not previously been assembled due to the genome's relatively large size and biological complexity that includes apomixis, polyploidy, and interspecific hybridization. We report here a fortuitous de novo assembly and annotation of a P. pratensis genome. Instead of sequencing the genome of a C4 grass, we accidentally sampled and sequenced tissue from a weedy P. pratensis whose stolon was intertwined with that of the C4 grass. The draft assembly consists of 6.09 Gbp with an N50 scaffold length of 65.1 Mbp, and a total of 118 scaffolds, generated using PacBio long reads and Bionano optical map technology. We annotated 256K gene models and found 58% of the genome to be composed of transposable elements. To demonstrate the applicability of the reference genome, we evaluated population structure and estimated genetic diversity in P. pratensis collected from three North American prairies, two in Manitoba, Canada and one in Colorado, USA. Our results support previous studies that found high genetic diversity and population structure within the species. The reference genome and annotation will be an important resource for turfgrass breeding and study of bluegrasses.

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.

The present study reports the effective removal of benzene in aqueous phase onto biochar. The adsorption capacity of benzene onto biochars made at different pyrolytic temperatures (e.g., 350, 550, and 750 °C) and from various feedstocks (e.g., grape pomace, rice husk, and Kentucky bluegrass) were investigated. The adsorption capacity of Kentucky bluegrass-derived biochar (KB-BC) prepared at 550 °C for benzene was better than other biochars, owing to the higher surface area and functional groups. The adsorption isotherms and kinetics model for benzene by KB-BC550 fitted the Freundlich and pseudo-first order, respectively. In addition, the results of response surface methodology (RSM) designed with biochar dose, reaction time, and benzene concentration showed the maximum adsorption capacity (ca. 136 mg BZ/g BC) similar to that from kinetic study. KB-BCs obtained as waste grass biomass may be a valuable adsorbent, and RSM may be a useful tool for the investigation of optimal conditions and results. [ABSTRACT FROM AUTHOR]

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 from2 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 stemC:P increased from2 to 4 years of plantation age and thenmaintained stability from4 to 9 years of plantation age. Root N:P showed an increasing trend from2 to 6 years of plantation age and relative stability from6 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 stemhad 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. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

Introduction: Evaluation 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.). Methods: In 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 discussion: Drought 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 FROM AUTHOR]

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.

Simple Summary: Rhizomes are underground stems that grow horizontally from the base of the stem and confer competitive, reproductive, foraging, and regenerative advantages to plants. They are especially important for forage and turfgrasses. Different phytohormones influence the growth and development of plant rhizomes in a variety of ways. Here, we compare the phytohormonal and metabolomic profiles of rhizomes from two contrasting Kentucky bluegrass (Poa pratensis), a perennial herb with variable rhizome traits materials: multi-rhizome and few-rhizome. We found that zeatin (ZT) was abundant in the multi-rhizome material, while indole-3-acetic acid (IAA), gibberellic acid (GA3), and abscisic acid (ABA) showed the opposite trend. Metabolomics revealed that the ABC transporter pathway and the histidine metabolism pathway, both related to cytokinin, were significantly expressed in the comparison group. Rhizomes are an ideal plant trait. Our findings provide new insights into the development of perennial rhizomatous herbs and a theoretical basis for the future breeding of rhizomatous plants. 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. [ABSTRACT FROM AUTHOR]

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

Global energy production is in high demand and is expanding its development into new landscapes, including grasslands. This expansion has intensive impacts on aboveground and belowground components of grasslands which need to be addressed during reclamation to promote long‐term ecological integrity. This study was conducted to ascertain how alternative reclamation practices may improve soil structure (i.e., compaction) while aiding in the creation of conditions that are conducive to both the establishment and continued growth of native grassland plant species. The grassland was reclaimed with different combinations of seeding mixtures (grass or grass and forb), ripping techniques (subsoil ripping or topsoil ripping), and the integration of mulch into the soil profile. Year, seed mixtures, and ripping techniques and their interactions significantly affected community composition and species diversity. Topsoil‐ripping and grass‐forb treatment had a higher association with native, perennial grasses while subsoil‐ripping and grass treatment favor more short‐lived species. Similar trends persisted across penetration resistance and soil moisture readings where topsoil‐ripping and grass‐forb treatment were different from subsoil‐ripping and grass treatments (p ≤ 0.10). Additionally, Kentucky bluegrass, an invasive grass species, increased by 76% over 1 year and was more common in the topsoil‐ripping and grass‐forb treatments. While early in the reclamation process, results suggest topsoil‐ripping and grass‐forb treatment are promising combination reclamation practices that can establish a native grassland community and initiate the improvement of compacted soil conditions. [ABSTRACT FROM AUTHOR]

Kentucky bluegrass (Poa pratensis L.) has become dominant in many portions of the northern Great Plains. During hot and/or dry periods, pastures consisting of mostly cool‐season grasses will most likely lack the productivity and diversity needed to provide sufficient forage for livestock. Determining the impact of weather conditions on the variation of forage production and nutritive response of Kentucky bluegrass is becoming increasingly important to agricultural producers. Sampling occurred at the USDA Northern Great Plains Research Laboratory near Mandan, North Dakota, USA. Kentucky bluegrass samples were clipped every 2–3 weeks in mowed and unmowed unfertilized rangeland plots during the growing seasons of 2017 and 2018. Samples were dried, weighed, ground to pass a 1‐mm sieve, and analysed for nutritive value. There are differences between the modelled supply of metabolizable energy and metabolizable protein and the requirements for cow‐calf pairs for all years and most months. Early defoliation of Kentucky bluegrass decreases productivity and nutritive value as the grazing season progresses. Adjusting management to allow an adequate growth interval and plant canopy cover throughout the year can ensure a more consistent supply of Kentucky bluegrass. Our data and models provide a glimpse into future scenarios, which allow producers to be more proactive in dealing with Kentucky bluegrass and projected changes in climate. [ABSTRACT FROM AUTHOR]

Poa pratensis, commonly known as Kentucky bluegrass, is a popular cool-season grass species used as turf in lawns and recreation areas globally. Despite its substantial economic value, a reference genome had not previously been assembled due to the genome's relatively large size and biological complexity that includes apomixis, polyploidy, and interspecific hybridization. We report here a fortuitous de novo assembly and annotation of a P. pratensis genome. Instead of sequencing the genome of a C4 grass, we accidentally sampled and sequenced tissue from a weedy P. pratensis whose stolon was intertwined with that of the C4 grass. The draft assembly consists of 6.09 Gbp with an N50 scaffold length of 65.1 Mbp, and a total of 118 scaffolds, generated using PacBio long reads and Bionano optical map technology. We annotated 256K gene models and found 58% of the genome to be composed of transposable elements. To demonstrate the applicability of the reference genome, we evaluated population structure and estimated genetic diversity in P. pratensis collected from three North American prairies, two in Manitoba, Canada and one in Colorado, USA. Our results support previous studies that found high genetic diversity and population structure within the species. The reference genome and annotation will be an important resource for turfgrass breeding and study of bluegrasses. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

Introduction Dandelion with the scientific name cTaraxacum sp.) from the Asteraceae family is one of the common weeds of turfgrasses and pastures. Post-growth control of weeds in established turfgrasses is crucial and ignoring it severely damages the aesthetic aspect of turfgrass. Chemical methods are commonly used to control weeds in established turfgrass (Karimmojeni et al, 2012). The use of herbicides helps in the management of weed control in damaged turf fields along with non-chemical methods such as correct mowing height, effective irrigation, sufficient fertilization, and timely weeding. Perennial broad-leaf weeds can be selectively controlled with herbicides. U-46 Combi Fluid, Duplosan super, and Ioxynil are suitable herbicides for controlling broadleaf weeds in narrow-leaf fields. Materials and Methods In order to control the dandelion in Kentucky bluegrass turf, a factorial experiment was conducted based on a completely randomized design with 3 replications and 9 treatments in September 2022, at the green space of Shahrekord University. Replications included lxl m2 plots and the factors included two herbicides of U46-Combi Fluid and Duplosan Super and their interaction with Ioxynil. All selected plots were infested with dandelion weed. The treatments included U46-combi fluid at two levels of 1.5 and 2 L ha"! (Ui.5 and u), Duplosan Super at two levels of 2 and 2.5 L ha"! (D2 and D2.5), their interaction with Ioxynil herbicide at two levels (0 and 2 L ha) (Io and I2), and the control (use of distilled water instead of herbicide). U-46 Combi Fluid and Duplosan Super herbicide treatments were applied at the end of September. Then, Ioxynil was applied 10 days after the first spraying. Finally, 15 days later, the effect of the treatments on the biomass characteristic of the dandelion shoots and the visual quality of turfgrass were recorded. After 50 days, the last spraying, the percentage of regrowth, herbicide control efficiency, and the biomass of turfgrass shoot were measured during the experiment. Variance analysis of data was done using SAS 9.1 statistical program and the comparison of means was conducted using LSD test (P<0.05). Results and Discussion The results showed the lowest fresh and dry weight of dandelion and the highest efficiency of herbicide were found in treatments u 2ل ب and D2.5+ 2ل. However, these treatments had not significantly different from D2I2 and U1.5+I treatments. The lowest percentage of regrowth was obtained in D2 2ل ب. The highest fresh weight of turfgrass was found in the control which had no significant difference with D2 2ل ب and Ui.5 2ل ب. Moreover, total chlorophyll in turfgrass leaves was improved by removing weeds. The amount of chlorophyll a, b, and total was higher in the Ul.5 treatment than in other treatments. Therefore, improving the greenness of turf could be due to more light being provided to turf leaves as a result of dandelion leaf removal or positive physiological effects of 2,4-D or MCPA. There were no differences among treatments for total chlorophyll, carotenoid, visual quality, dry weight of turfgrass, and dandelion control percentage. Therefore, D2 2ل ب and Ul.5 + 2ل can be recommended, due to the higher fresh turf weight, the good control of dandelion, and the low rate of regrowth of weed. Conclusion Application of Duplosan Super and then Ioxynil, both with a concentration of 2.0 L ha"! and/or U-46 Combi Fluid with a concentration of 1.5 L ha"! and then Ioxynil with a concentration of 2.0 L ha"! treatments are recommended due to the high weight of turfgrass, the reasonable control of dandelions, and their reduction of regrowth. In addition, leaf chlorophyll of Kentucky bluegrass treated with of u-46 Combi Fluid with a concentration of 1.5 L ha"1 was higher than in other treatments. It also had a higher turfgrass fresh weight than the 2.0 L ha"1 of u-46 Combi Fluid treatment. Duplosan Super (2.5 L ha"1) and then Ioxynil (2.0 L ha"1) treatment led to a decrease in turfgrass fresh weight compared to the same treatment without Ioxynil. In conclusion. Ioxynil concentrations at high levels did not cause visible damage, but had adverse effects on turfgrass growth, suggesting that a lower dose should be studied. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

Kentucky bluegrass (Poa pratensis) is known for its high cadmium (Cd) tolerance and accumulation, and it is therefore considered to have the potential for phytoremediation of Cd-contaminated soil. However, the mechanisms underlying the accumulation and tolerance of Cd in Kentucky bluegrass are largely unknown. In this study, we examined variances in the transcriptome and metabolome of a Cd-tolerant variety (Midnight, M) and a Cd-sensitive variety (Rugby II, R) to pinpoint crucial regulatory genes and metabolites associated with Cd response. We also validated the role of the key metabolite, l -phenylalanine, in Cd transport and alleviation of Cd stress by applying it to the Cd-tolerant variety M. Metabolites of the M and R varieties under Cd stress were subjected to co-expression analysis. The results showed that shikimate-phenylpropanoid pathway metabolites (phenolic acids, phenylpropanoids, and polyketides) were highly induced by Cd treatment and were more abundant in the Cd-tolerant variety. Gene co-expression network analysis was employed to further identify genes closely associated with key metabolites. The calcium regulatory genes, zinc finger proteins (ZAT6 and PMA), MYB transcription factors (MYB78 , MYB62 , and MYB33), ONAC077 , receptor-like protein kinase 4 , CBL-interacting protein kinase 1 , and protein phosphatase 2A were highly correlated with the metabolism of phenolic acids, phenylpropanoids, and polyketides. Exogenous l -phenylalanine can significantly increase the Cd concentration in the leaves (22.27%–55.00%) and roots (7.69%–35.16%) of Kentucky bluegrass. The use of 1 mg/L of l -phenylalanine has been demonstrated to lower malondialdehyde levels and higher total phenols, flavonoids, and anthocyanins levels, while also significantly enhancing the uptake of Cd and its translocation from roots to shoots. Our results provide insights into the response mechanisms to Cd stress and offer a novel l -phenylalanine-based phytoremediation strategy for Cd-containing soil. [Display omitted] • Metabolites important to the response to Cd stress were identified in Kentucky bluegrass. • Transcriptional regulators of these key metabolites were explored. • l -phenylalanine was determined to play a key role in orchestrating the related metabolism. • Exogenous l -phenylalanine enhanced long-distance translocation and accumulation of Cd. [ABSTRACT FROM AUTHOR]

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.

Kentucky bluegrass (Poa pratensis L., KB) demonstrates superior performance in both cadmium (Cd) accumulation and tolerance; however, the regulatory mechanisms and detoxification pathways in this species remain unclear. Therefore, phenotype, root ultrastructure, cell wall components, proteomics, transcriptomics, and metabolomics were analyzed under the hydroponic system to investigate the Cd tolerance and accumulation mechanisms in the Cd-tolerant KB variety 'Midnight (M)' and the Cd-sensitive variety 'Rugby II (R)' under Cd stress. The M variety exhibited higher levels of hydroxyl and carboxyl groups as revealed by Fourier transform infrared spectroscopy spectral analysis. Additionally, a reduced abundance of polysaccharide degradation proteins was observed in the M variety. The higher abundance of glutathione S-transferase and content of L-cysteine-glutathione disulfide and oxidized glutathione in the M variety may contribute to better performance of the M variety under Cd stress. Additionally, the R variety had an enhanced content of carboxylic acids and derivatives, increasing the Cd translocation capacity. Collectively, the down-regulation of cell wall polysaccharide degradation genes coupled with the up-regulation of glutathione metabolism genes enhances the tolerance to Cd stress in KB. Additionally, lignification of the endodermis and the increase in carboxylic acids and derivatives play crucial roles in the redistribution of Cd in KB. [Display omitted] • Cd-tolerant variety M accumulated more Cd in the leaves. • Cell wall, glutathione, and organic acid metabolism are involved in responding Cd stress. • Cell wall and GSH metabolism were correlated with Cd resistance in M and R varieties. • Increased organic acids in the R variety contributed to long-distance Cd translocation. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Endodermis thickening restricts long-distance Cd transport from roots to shoots. • Cd-tolerant cultivar M exhibits increased lignin and suberin deposition. • Hemicellulose and ion-soluble pectin fixed more Cd in Cd-tolerant cultivar roots. • Lignin, suberin, hemicellulose, and pectin metabolism genes are activated by Cd. • Cultivar M exhibits lower expression of cell wall polysaccharide degradation genes. [ABSTRACT FROM AUTHOR]

The inflorescence is composed of spikes, and the spike is the carrier of grass seed formation and development, so the development status of inflorescence implies grass seed yield and quality. So far, the systematic analysis of inflorescence development of Kentucky bluegrass has not been reported. The development process of the female gametophyte of wild germplasm materials of Kentucky bluegrass in Gannan, Gansu Province of China (KB-GN), was observed. Based on this, the key developmental stages of inflorescence in KB-GN were divided into premeiosis (GPreM), meiosis (GM), postmeiosis (GPostM), and anthesis (GA), and four stages of inflorescence were selected to analyze the transcriptome expression profile. We found that its sexual reproduction formed a polygonum-type embryo sac. Transcriptome analysis showed that 4256, 1125, 1699, and 3127 genes were highly expressed in GPreM, GM, GPostM, and GA, respectively. And a large number of transcription factors (TFs) such as MADS-box, MYB and NAC, AP2, C2H2, FAR1, B3, bHLH, WRKY, and TCP were highly expressed throughout the inflorescence development stages. KEGG enrichment and MapMan analysis showed that genes involved in plant hormone metabolism were also highly expressed at the entire stages of inflorescence development. However, a few TFs belong to stage-specific genes, such as TRAF proteins with unknown function in plants was screened firstly, which was specifically and highly expressed in the GPreM, indicating that TRAF may regulate the preparatory events of meiosis or be essential for the development of megaspore mother cell (MMC). The expression patterns of 15 MADS-box genes were analyzed by qRT-PCR, and the expression results were consistent with that of the transcriptome. The study on the inflorescence development of KB-GN will be great significant works and contribution to illustrate the basic mechanism of grass seeds formation and development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]

The introduction of well-adapted species, such as Trifolium subterraneum (subclover) and Poa pratensis (Kentucky bluegrass), might enhance the forage yield and quality of dehesa pastures for feeding livestock. However, the climatic hardness and poor soils in these agrosystems may limit plant establishment and development. Since fungal endophytes have been found to alleviate the environmental stresses of their host, the aim of this study was to assess the effect of five isolates on forage yield, nutritive value, and plant mineral uptake after their inoculation in the two abovementioned plant species. Two experiments were established (under greenhouse and field conditions) using plants inoculated with two isolates in 2012/2013 (Epicoccum nigrum, Sporormiella intermedia) and three isolates in 2013/2014 (Mucor hiemalis, Fusarium equiseti, Byssochlamys spectabilis). Fusarium equiseti (E346) increased the herbage yield of T. subterraneum under greenhouse conditions, and B. spectabilis improved the forage quality of T. subterraneum by reducing fiber content and of P. pratensis by increasing crude protein. S. intermedia increased the mineral uptake of Ca, Cu, Mn, Pb, Tl, and Zn in subclover, and M. hiemalis increased the uptake of K and Sr in Kentucky bluegrass. These results evidence the potential of the studied fungal endophytes to enhance herbage yield and nutritional value of forage, although further studies should include all of the target forage species as certain host specificity in the effect was observed. [ABSTRACT FROM AUTHOR]

In the current study, the effects of De Greef & Jacobs (DG), Linsmaier & Skoog (LS), Murashige & Skoog (MS), and Schenk & Hildebrandt (SH) media were tested on seed germination and plant development in Poa pratensis cv. Evora. The highest germination rate (83±2.74%) was found on SH medium, whereas LS medium gave the lowest (46±4.18%) germination rate. The statistically same leaf numbers were recorded from SH (2.10±0.27) and DG (2.12±0.18) media. SH and DG media gave 4.28±0.28 cm and 4.16±0.31 cm mean leaf lengths, respectively. SH medium gave the maximum mean root number (3.09±0.26). However, the LS medium gave the lowest mean root number (1.84±0.10). The longest roots (1.43±0.19 cm) were observed in the plants grown in SH medium. However, DG medium had the minimum mean root length (0.81±0.08 cm). In conclusion, SH medium should be preferred over the other medium tested in in vitro tissue culture studies on the species to increase the biomass production yield. The efficacy of SH medium in the in vitro propagation of P. pratensis could be increased using growth promoters. [ABSTRACT FROM AUTHOR]