Search

Root-knot nematodes were discovered in severely declining creeping bentgrass putting greens at a golf course in Indian Wells, Riverside County, California. The exhibited disease symptoms included chlorosis, stunted growth, and dieback. Based on morphological examination and measurements of J2 females and males, it was suggested that the causal pathogen was Meloidogyne marylandi. This identification was confirmed by analysis of the D2-D3 expansion segments of 28S rRNA and COI gene sequences. The host status of 28 plant species was evaluated in greenhouse trials. All tested monocots, except rye and Allium species, were found to be hosts, while no reproduction occurred on dicots. Temperature-tank experiments helped determine that the life cycle of M. marylandi was completed between 17–35 °C, with a base temperature of 8.3 °C and a required heat sum of 493 degree-days (DD). In greenhouse trials in pasteurized soil and near-ideal growing conditions, M. marylandi did not cause significant growth reduction of creeping bentgrass cv. Penn A-4, even at very high J2 inoculation densities. It is highly probable that other biotic and abiotic factors contributed to the observed putting green damage.

Coppe and zinc are priority pollutants in city soils. Copper and zinc are the limiting factors for lawn grasses. Cell selection can increase the resistance of lawn grasses to zinc and copper. The effect of zinc on the morphogenic ability of the callus was determined. The results of this study showed that zinc is less toxic to calli than copper. The method of obtaining lawn grass resistant to zinc has been developed. The results were used to develop the cell selection technology for obtaining plants resistant to the complex effect of zinc and copper. Concentrations of Copper (75 mg/l) and zinc (150 mg/L) were selected as selective. The author developed the cell selection scheme for obtaining plants resistant to the complex effect of Cu and Zn. The regenerants showed increased resistance to copper and zinc. [ABSTRACT FROM AUTHOR]

The challenge of managing invasive weed species continues to affect the agricultural industry, presenting ecological, economic, and agronomic hurdles that lead to over 100 billion USD in annual crop losses globally. One such concern is the management of Agrostis stolonifera L., commonly known as creeping bentgrass, particularly due to its ability to form hybrids. This scenario underscores the urgent need for innovative, effective, and environmentally sustainable herbicides, steering the focus toward natural substances as potential candidates. We report here a promising natural lactone, commonly known as menthalactone, which is derived from Mentha piperita L. Its phytotoxic activity was assessed against the monocot, bentgrass, and a dicot, lettuce (Lactuca sativa L.). Menthalactone displayed outstanding activity against bentgrass and was further evaluated for phytotoxic characteristics. The germination of A. stolonifera seeds was significantly inhibited with an IC50 value of 4.9 ± 1.2 µM. In contrast to bentgrass seeds, Lemna pausicostata L. plants were less responsive to menthalactone treatment, shown by an IC50 of 293.4 ± 70.6 µM. Both species are monocots, and the results suggest that menthalactone might have effects on seed germination but not on the metabolism of green tissues. The susceptibility of three common, obnoxious weed species, i.e., ryegrass (Lilium perenne), barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), and crabgrass (Digitaria sanguinalis (L.) Scop.), to menthalactone was assessed. Menthalactone at 1000 µM completely inhibited the germination of all three species of grasses, while 330 µM inhibited germination by less than 50%. The post-emergence application of menthalactone at 1% did not produce a significant inhibitory effect against ryegrass, barnyard grass, or crabgrass.

The challenge of managing invasive weed species continues to affect the agricultural industry, presenting ecological, economic, and agronomic hurdles that lead to over 100 billion USD in annual crop losses globally. One such concern is the management of Agrostis stolonifera L., commonly known as creeping bentgrass, particularly due to its ability to form hybrids. This scenario underscores the urgent need for innovative, effective, and environmentally sustainable herbicides, steering the focus toward natural substances as potential candidates. We report here a promising natural lactone, commonly known as menthalactone, which is derived from Mentha piperita L. Its phytotoxic activity was assessed against the monocot, bentgrass, and a dicot, lettuce (Lactuca sativa L.). Menthalactone displayed outstanding activity against bentgrass and was further evaluated for phytotoxic characteristics. The germination of A. stolonifera seeds was significantly inhibited with an IC50 value of 4.9 ± 1.2 µM. In contrast to bentgrass seeds, Lemna pausicostata L. plants were less responsive to menthalactone treatment, shown by an IC50 of 293.4 ± 70.6 µM. Both species are monocots, and the results suggest that menthalactone might have effects on seed germination but not on the metabolism of green tissues. The susceptibility of three common, obnoxious weed species, i.e., ryegrass (Lilium perenne), barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), and crabgrass (Digitaria sanguinalis (L.) Scop.), to menthalactone was assessed. Menthalactone at 1000 µM completely inhibited the germination of all three species of grasses, while 330 µM inhibited germination by less than 50%. The post-emergence application of menthalactone at 1% did not produce a significant inhibitory effect against ryegrass, barnyard grass, or crabgrass. [ABSTRACT FROM AUTHOR]

Copyright of Flora Montibérica is the property of Flora Montiberica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two cool-season putting green turfgrass species, annual bluegrass and creeping bentgrass, are differential in ice encasement tolerance. Physiological mechanisms associated with creeping bentgrass ice encasement tolerance and annual bluegrass susceptibility are not understood. The objectives were to evaluate oxygen, ethylene, and CO2 content within the upper soil space of the plants while frozen and immediately after ice melt after 0, 5, 10, 20, and 28 days of ice encasement (2.54 cm of ice) in growth chamber conditions. Following ice melt, plant samples were separated into leaf, crown, and root tissues and used to evaluate carbohydrate and amino acid content. Annual bluegrass exhibited higher damage (slower recovery rates) on most sampling days compared with creeping bentgrass. The organs that were most damaged and exhibited a differential principal component analysis snapshot, were the leaf and crown tissues. Creeping bentgrass may preserve leaf and crown tissues for postwinter recovery whereas significant metabolic changes occur in annual bluegrass leaves and crowns. Creeping bentgrass retained total amino acids in leaves following ice encasement whereas total leaf amino acid levels declined in annual bluegrass. Specific carbohydrates and amino acids such as the ability to maintain high levels of fructose, asparagine, and proline may be important indicators of the tolerance to ice encasement stress. On the basis of more prominent carbohydrate and amino acid loss in leaves and crowns and higher levels of CO2 evolution, annual bluegrass may exhibit a higher metabolism and/or tissue damage during ice encasement compared with creeping bentgrass, which could reduce spring recuperative potential.

Control of plant-parasitic nematodes (PPNs) on golf putting greens with nematicides is dependent on the seasonal occurrence and depth distribution of target PPN populations. This study aimed to determine if plant-parasitic nematode populations on golf course putting greens in Missouri and Indiana peaked at a targetable depth at a specific time in the year, focusing primarily on lance (Hoplolaimus spp.) and root-knot (Meloidogyne spp.) nematodes. To elucidate species diversity in the region, rDNA from a subset of lance and root-knot nematodes was sequenced and analyzed, with additional micromorphology of a lance nematode assessed in scanning electron micrographs (SEM). Soil samples were taken to a depth of 25 cm and stratified into 5 cm increments during April, June, August and October at seven sites across Missouri, three in the Kansas City metro of Kansas in 2021 and in ten sites across Indiana in 2022. Samples were stratified in five-centimeter increments and aggregated for a total of 100 cm3 of soil at each depth for each sampling. Samples were processed using a semi-automatic elutriator followed by the sucrose-flotation method, and populations were counted using a hemocytometer and recorded. For molecular characterization, rDNA was extracted and analyzed from 31 individual lance nematodes from one site in Missouri and eight sites in Indiana, and 13 root-knot nematodes from nine sites across Indiana. A significant interaction occurred between sampling month and depth for lance and ring nematodes Missouri/KS, with both PPN populations peaking at the 0–5 cm depth during October, which is well after most targeted nematicide applications are applied. Ring nematodes in Indiana did not follow this trend and were most abundant in August at a depth of 0–5 cm. No significant interaction between depth and month occurred for lance or root-knot nematodes in Indiana, or root-knot nematodes in Missouri/KS. Hoplolaimus stephanus and H. magnistylus were the lance species identified on golf greens, and Meloidogyne naasi, M. graminicola and M. marylandi were the root-knot species identified. Scanning-electron micrographs confirmed morphological characteristics unique to H. stephanus.

Copyright of Flora Montibérica is the property of Flora Montiberica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cultural and environmental factors can place creeping bentgrass (Agrostis stolonifera) under extreme stress during the summer months. This stress, coupled with the growth adaptation of creeping bentgrass, can result in shallow, poorly rooted stands of turf. To enhance root zone oxygen and rooting of creeping bentgrass, golf courses use methods such as core and solid-tine aerification, and sand topdressing. An additional method of delivering oxygen to the soil could be irrigation with nanobubble-oxygenated water. The properties of nanobubbles (NBs) allow for high gas dissolution rates in water. Irrigating with NB-oxygenated water sources may promote increased rooting of creeping bentgrass putting greens during high-temperature periods and lead to a more resilient playing surface. The objectives of this study include comparing the effects of irrigation with NB-oxygenated water sources with untreated water sources on creeping bentgrass putting green root zone and plant health characteristics using field and controlled environment experiments. Treatments included NB-oxygenated potable water and irrigation pond water, and untreated potable and irrigation pond water. In the field, NB-oxygenated water did not enhance plant health characteristics of creeping bentgrass. In 1 year, NB-oxygenated water increased the daily mean partial pressure of soil oxygen from 17.48 kPa to 18.21 kPa but soil oxygen was unaffected in the other 2 years of the trial. Subsurface irrigation with NB-oxygenated water did not affect measured plant health characteristics in the greenhouse. NB-oxygenation of irrigation water remains an excellent means of efficiently oxygenating large volumes of water. However, plant health benefits from NB-oxygenated irrigation water were not observed in this research.

Plant biotechnology methods can be used in urban environments. Cell selection, genetic engineering, and micropropagation hold great promise among biotechnological methods. Two main applications for the use of cell selection for urban plants are possible in future. The first is the use of this technology in urban greening to improve plant resistance. The second is phytoremediation of contaminated urban soils. Micropropagation can be used for urban plant reproduction. The use of genetic engineering is promising for obtaining new varieties of urban plants with high ornamental qualities. When using genetic engineering techniques, environmental risks should be taken into account. The use of biotechnology for the urban environment will contribute to the development of applied biotechnology, urban biology, urban natural sciences and urban technical sciences. Future ornamental urban plants will change, but they will always play an important role in people's lives.

Copyright of Flora Montibérica is the property of Flora Montiberica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Creeping bentgrass (Agrostis stolonifera L.) is a turfgrass species that is widely used on golf courses throughout the United States. In field settings, plants are often subjected to more than one stress at a time, and studying stresses independently is likely insufficient. Stresses, such as heat stress and salt stress, can affect plant hormone levels and, in turn, plant hormone levels can affect how well the plant tolerates stress. The objectives of the experiments were to determine if the levels of heat stress and salt stress used would be detrimental to creeping bentgrass health, and if applying plant growth regulators could improve plant health during stress. During the first experiment, creeping bentgrass was transplanted to hydroponics systems in two different growth chambers. One chamber was set to have day and night temperatures of 35 °C and 30 °C (heat stress), respectively, and the other had day and night temperatures of 25 °C and 20 °C, respectively. Within each chamber, one block received a 50 mM NaCl treatment (salt stress) and the other did not (control). The stress treatments were applied for 14 days. Results of the first experiment indicated that the treatments were sufficient to negatively affect creeping bentgrass growth and health as indicated by fresh shoot and root weights, tillering, electrolyte leakage, and total chlorophyll content (TCC). There were significant interactions of temperature × salt level detected for shoot and root weights and electrolyte leakage. Plants that were exposed to both heat stress and salt stress were more negatively affected than plants exposed to either heat stress or salt stress alone for all metrics except for tillering. The presence of salt reduced tillering regardless of the temperature regimen. During the second experiment, plants were treated the same, but the plant growth regulator (PGR) treatments were also applied. The PGR treatments consisted of two different gibberellic acid (GA) synthesis inhibitor products, 2,4-dichlorophenoxyacetic acid, two different rates of aminoethoxyvinylglycine (AVG), an ethylene synthesis suppressor, and plants that were not treated with the PGR. In addition to the measurements of plant health and growth, dry shoot and root weights were measured. For the TCC, there was a two-way interaction between temperature × PGR treatment. For electrolyte leakage, there was a three-way interaction between temperature × salt level × PGR treatment. Combined heat stress and salt stress negatively affected all plants regardless of PGR treatment, but there were differences between PGR treatments. Plants treated with AVG exhibited improved health and growth compared with the other PGR treatments. These plants had the highest shoot and root masses. Plants treated with GA synthesis inhibitors had the lowest shoot and root masses as well as the lowest TCC when subjected to stress.

Creeping bentgrass (Agrostis stolonifera L.) is a turfgrass species that is widely used on golf courses throughout the United States. In field settings, plants are often subjected to more than one stress at a time, and studying stresses independently is likely insufficient. Stresses, such as heat stress and salt stress, can affect plant hormone levels and, in turn, plant hormone levels can affect how well the plant tolerates stress. The objectives of the experiments were to determine if the levels of heat stress and salt stress used would be detrimental to creeping bentgrass health, and if applying plant growth regulators could improve plant health during stress. During the first experiment, creeping bentgrass was transplanted to hydroponics systems in two different growth chambers. One chamber was set to have day and night temperatures of 35 °C and 30°C (heat stress), respectively, and the other had day and night temperatures of 25 °C and 20°C, respectively. Within each chamber, one block received a 50 mM NaCl treatment (salt stress) and the other did not (control). The stress treatments were applied for 14 days. Results of the first experiment indicated that the treatments were sufficient to negatively affect creeping bentgrass growth and health as indicated by fresh shoot and root weights, tillering, electrolyte leakage, and total chlorophyll content (TCC). There were significant interactions of temperature x salt level detected for shoot and root weights and electrolyte leakage. Plants that were exposed to both heat stress and salt stress were more negatively affected than plants exposed to either heat stress or salt stress alone for all metrics except for tillering. The presence of salt reduced tillering regardless of the temperature regimen. During the second experiment, plants were treated the same, but the plant growth regulator (PGR) treatments were also applied. The PGR treatments consisted of two different gibberellic acid (GA) synthesis inhibitor products, 2,4-dichlorophenoxyacetic acid, two different rates of aminoethoxyvinylglycine (AVG), an ethylene synthesis suppressor, and plants that were not treated with the PGR. In addition to the measurements of plant health and growth, dry shoot and root weights were measured. For the TCC, there was a two-way interaction between temperature x PGR treatment. For electrolyte leakage, there was a three-way interaction between temperature x salt level x PGR treatment. Combined heat stress and salt stress negatively affected all plants regardless of PGR treatment, but there were differences between PGR treatments. Plants treated with AVG exhibited improved health and growth compared with the other PGR treatments. These plants had the highest shoot and root masses. Plants treated with GA synthesis inhibitors had the lowest shoot and root masses as well as the lowest TCC when subjected to stress. [ABSTRACT FROM AUTHOR]

Brown blotch caused by Rhizoctonia solani is among the most common Agrostis lawn diseases. Evidence shows that 2,3-butanediol (2,3-BD) induces and improves plant disease resistance. Herein, we treated Agrostis stolonifera L. Penn-A4 with 250 µmol/L 2,3-BD to induce resistance to brown blotch (Rhizoctonia solani). Changes in leaf ultrastructure were observed with a TECNAI-G2 (TF20) electron microscope. The cell wall composition and phenolic acids used as precursors in lignin synthesis were determined by spectrophotometry and high-performance liquid chromatography. The disease index of creeping bentgrass decreased significantly following 2,3-BD induction. The disease index of the uninduced treatment increased to 70.45% on the 15th day after inoculation, 3.26 times higher than the 2,3-BD-induced treatment. The degree of damage to cells was significantly reduced after induction, chloroplasts were completely spindle shaped and appeared close to the cell wall, the cell wall was thicker with visible folds, and the cell wall cross section was more visible. The levels of lignin, cellulose, hemicellulose, pectin, and hydroxyproline-rich glycoprotein (HRGP) in leaves were significantly higher in induced plants than in non-induced plants. Lignin, hemicellulose, pectin, and cellulose of the induced plants peaked on the 13th, 9th, 11th, and 7th days, respectively, and were 5.7, 16.5, 0.9, and 17.6% higher than those of non-induced plants, whereas HRGP increased by 22.8 and 42.5% on days 7–9 compared to non-induced plants. The induced plants had significantly higher levels of p-coumaric acid, caffeic acid, ferulic acid, and sinapic acid. p-Coumaric acid peaked on the 7th and 15th days, when it was 1.38 and 1.12 times higher than in non-induced plants, respectively, while caffeic acid, ferulic acid, and sinapic acid peaked on the 9th, 11th, and 13th days, when it was 1.39, 1.11, and 1.16 times higher than in non-induced plants. The 2,3-BD treatment effectively strengthened cell wall structure and increased plant resistance by increasing the content of constituent substances in the cell wall and strengthening the cell wall. Also, the content of precursor substances for lignin synthesis increased. The findings demonstrate that 2,3-BD can effectively improve plant disease resistance. [ABSTRACT FROM AUTHOR]

Lead is one of the priority soil pollutants among heavy metals. To increase the species diversity of ecosystems, it is necessary to increase the resistance of plants to lead. The aim of the work was to obtain plants resistant to lead. The objects of our study were to lawn grasses. The effect of lead on the growth and regenerative ability of calli was determined. The results of this work showed that lead is less toxic to calli than copper. Biotechnological method for obtaining lead resistant plants has been developed. The effect of lead on the growth of regenerants and original plants was determined. Agrostis stolonifera plants that are obtained after cell selection have demonstrated a high degree of resistance to lead. Can the developed technology be used for other lawn grasses? We obtained lead resistant plants Festuca rubra. Therefore, using cell selection can increase the tolerance of lawn grasses to lead. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate the role of bacteria colonising mycorrhizal hyphae in organically bound sulfur mobilisation, the dominant soil sulfur source that is not directly plant available. The effect of an intact mycorrhizal symbiosis with access to stable isotope organo-34S enriched soils encased in 35 µm mesh cores was tested in microcosms with Agrostis stolonifera and Plantago lanceolata. Hyphae and associated soil were sampled from static mesh cores with mycorrhizal ingrowth and rotating mesh cores that exclude mycorrhizal ingrowth as well as corresponding rhizosphere soil, while plant shoots were analysed for 34S uptake. Static cores increased uptake of 34S at early stages of plant growth when sulfur demand appeared to be high and harboured significantly larger populations of sulfonate mobilising bacteria. Bacterial and fungal communities were significantly different in the hyphospheres of static cores when compared to rotating cores, not associated with plant hosts. Shifts in bacterial and fungal communities occurred not only in rotated cores but also in the rhizosphere. Arylsulfatase activity was significantly higher in the rhizosphere when cores stayed static, while atsA and asfA gene diversity was distinct in the microcosms with static and rotating cores. This study demonstrated that AM symbioses can promote organo-S mobilization and plant uptake through interactions with hyphospheric bacteria, enabling AM fungal ingrowth into static cores creating a positive feedback-loop, detectable in the microbial rhizosphere communities. [ABSTRACT FROM AUTHOR]

Nanomaterials play a crucial role in various applications, but their environmental impact necessitates effective recycling strategies. This study investigates the effects of different ZnO nanoparticles (ZnO-NPs) sizes (0, 30, 50, and 90 nm) on Agrostis stolonifera, focusing on physiological and biochemical responses, root exudate, and microbial community structure. The results showed that the most optimal physiological and biochemical responses, including enhanced plant growth and increased activities of superoxide dismutase, peroxidase, and catalase, were observed at 50 nm ZnO-NPs. Agrostis stolonifera accumulated more ZnO-NPs at 30 nm, with Zn content in root and leaf tissues reaching 186 mg/kg and 294 mg/kg, respectively. Meanwhile, SEM-Mapping and TEM analyses confirmed the absorption and transport of ZnO-NPs within Agrostis stolonifera. Furthermore, root exudates analysis revealed an increase in the types of organic matter secreted by roots at 30 nm and 50 nm ZnO-NPs, while 90 nm ZnO-NPs had the opposite effect. 16S rRNA gene sequencing showed that the species diversity and uniformity of root microorganisms exhibited contrasting trends with increasing ZnO-NPs size, with roots exposed to 50 nm ZnO-NPs showed higher species richness than those exposed to 30 nm or 90 nm. However, beneficial microorganisms such as Bryobacter and Methylophilus were inhibited by 90 nm ZnO-NPs. This study provides novel insights into a potential ZnO-NPs recycling strategy in soil using Agrostis stolonifera, offering a means to mitigate nanoparticle-induced damage to soil and crops., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Heat stress symptoms in cool-season plants are characterized by loss of chlorophyll (Chl) and membrane stability, as well as oxidative damage. The objectives of this study were to determine whether foliar application of β-sitosterol, a naturally occurring plant metabolite, may promote heat tolerance by suppressing heat-induced leaf senescence as indicated by the maintenance of healthy turf quality (TQ), and Chl and membrane stability; and to determine its roles in regulating antioxidant metabolism in creeping bentgrass (Agrostis stolonifera). ‘Penncross’ plants were exposed to heat stress (35/30 °C day/night) optimal temperature conditions (nonstressed control, 22/17 °C day/night) for a duration of 28 days in environment-controlled growth chambers. Plants were foliar-treated with β-sitosterol (400 µM) or water only (untreated control) before heat stress, and at 7-day intervals through 28 days of heat stress. Plants treated with β-sitosterol had significantly greater TQ and Chl content, and significantly less electrolyte leakage (EL) than untreated controls at 21 and 28 days of heat stress. Application of β-sitosterol reduced malondialdehyde (MDA) content significantly at 21 and 28 days of heat stress, and promoted the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) from 14 through 28 days of heat stress. β-Sitosterol effectively improved heat tolerance through suppression of leaf senescence in creeping bentgrass exposed to heat stress in association with the alleviation of membrane lipid peroxidation and activation of the enzymatic antioxidant system.

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

Spermine (SPM) is involved in response to abiotic stress in plants, but the potential role of SPM in regulating senescence has not been well documented. Objectives of this study were to examine the effect of changes in endogenous polyamines (PAs) by SPM application on improving heat tolerance of creeping bentgrass (Agrostis stolonifera) and explore the SPM-regulated senescence associated with alterations of water and oxidative balance, photosynthesis, and heat shock proteins under heat stress. The results showed that persistent high temperature caused severe oxidative damage and significant decreases in chlorophyll (Chl) content, photosynthetic efficiency, and leaf water content leading to premature senescence in creeping bentgrass, as reflected by a significant upregulation of transcriptions of senescence-associated genes (AsSAG39, Ash36, and Asl20). The improvement of endogenous spermidine (SPD) and SPM content induced by SPM application could significantly alleviate heat stress damage to creeping bentgrass through maintaining higher Chl content, net photosynthetic rate, photochemical efficiency, and performance index on absorption basis, promoting osmotic adjustment ability and antioxidant enzyme (superoxid dismutase, catalase, peroxidase, and ascorbate peroxidase) activities to enhance the scavenging capacity of reactive oxygen species, and upregulating transcriptions of heat shock protein (HSP) genes (HSP90-5, HSP90.1-b1, HSP82, HSP70, HSP26.7, HSP17.8, and HSP12) helping to maintain normal synthesis and functions of proteins under high temperature stress, thereby delaying heat-induced leaf senescence. These findings reveal an important role of PAs in regulating senescence in perennial plants exposed to a high temperature environment.

Effects of amino acids and nitrogen on plant regrowth or recovery from drought stress remain largely unknown. The objectives of this study were to examine how gamma-aminobutyric acid (GABA) or proline, alone and in combination, or inorganic nitrogen [ammonium nitrate (NN)] may differentially affect turf performance during drought stress and rewatering, and to determine which specific endogenous amino acids regulated by GABA, proline, or NN priming were associated with plant tolerance to drought stress and postdrought recuperation in cool-season grass species. Creeping bentgrass (Agrostis stolonifera cv. Penncross) planted in porous ceramic fritted clay medium were exposed to well-watered conditions or drought stress by withholding irrigation for 21 days in growth chambers. Plants were treated with water (untreated control), GABA, or proline alone and in combination, or NN through foliar spray before drought stress and every 7 days during the 21-day stress period. For postdrought recovery, at 21 days of drought treatment, plants were rewatered for 14 days to return soil water content to prestress levels. Plants treated with GABA or proline alone or in combination maintained higher turf quality (TQ), dark green color index (DGCI), and stolon length by 21 days of drought stress, whereas proline-treated plants also maintained higher leaf relative water content (RWC) during drought as well as longer stolon length during rewatering. Plants treated with NN maintained higher TQ and leaf RWC during drought and had improved percent canopy cover, DGCI, and stolon length during postdrought rewatering. Accumulation of endogenous amino acids under drought stress, including proline and alanine, for proline-treated creeping bentgrass may have contributed to the enhancement of drought tolerance and postdrought regrowth. Nitrogen-enhanced accumulation of GABA, proline, and glutamic acid may have played a role in active amino acid assimilation and subsequent postdrought regrowth. Results from this study indicate that GABA or proline were mainly effective in promoting the tolerance of creeping bentgrass to drought stress while inorganic NN was effective in promoting rapid postdrought recovery and regrowth potential through the activation of amino acid metabolism. Endogenous amino acids, including GABA, proline, alanine, and glutamic acid, may be used as biomarkers to select for drought-tolerant plants and biostimulant components for improvement of drought stress tolerance and poststress recovery in cool-season turfgrass species.

There is evidence that 2,3-butanediol (2,3-BD) can increase resistance to plant diseases via the induced systemic resistance (ISR) pathway. Brown blotch is caused by Rhizoctonia solani and is regarded as among the foremost diseases of Agrostis lawns. We sought to explore the effects of 2,3-BD treatments on the antioxidant metabolism and sucrose metabolism in brown blotch disease of creeping bentgrass (Agrostis stolonifera cv. Penn A4). The results showed that when exogenous 2,3-BD was applied by soil injection before creeping bentgrass seedlings were inoculated with Rhizoctonia solani for nine days, such pretreatment could effectively reduce the disease index of turf brown blotch. However, we reported reduced accumulation of reactive oxygen species (ROS), including the H2O2 content and O2•− generation rate, the OH• concentration, lipoxygenase activity, and the malondialdehyde content following pathogen infection. 2,3-BD induction amplified the activities of antioxidant enzymes (catalase, superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase) while simultaneously increasing glutathione and ascorbate contents. These responses are approaches to scavenge ROS associated with pathogen infection. The pathogen also triggers a change in sugar contents and defense reactions in plants (including the redistribution of plant sugars). Of note, 2,3-BD pretreatment can regulate sucrose synthase-synthesis and sucrose synthase-cleavage and regulate the activity of sucrose phosphate synthase and sucrose phosphate phosphatase in plant sucrose metabolism. These events contribute to significant changes in the soluble sugar components and reduce the loss of sucrose. Collectively, these data strongly suggest that 2,3-BD can induce both antioxidant metabolism and sucrose metabolism in creeping bentgrass, thereby increasing its resistance to brown blotch (Rhizoctonia solani). [ABSTRACT FROM AUTHOR]

Cell selection was used to obtain copper-resistant plants. Developed technologies for obtaining copper-resistant plants Agrostis stolonifera and Chrysanthemum carinatum can be applied to other plant species. We obtained copper-resistant plants Festuca rubra, Brachycome iberidifolia and Linum perenne. The concept of obtaining plants resistant to copper has been developed. This concept consists of two methods. The first method is applicable when calli is highly sensitive to copper. The second method is applicable when calli are moderately sensitive to copper. [ABSTRACT FROM AUTHOR]

Deicing reagents are priority soil pollutants in urban ecosystems. Sodium chloride is one of the priority deicing reagents. Sodium chloride is limiting the spread of lawn grass. We first showed the possibility of using environmental biotechnology in urban greening to obtain lawn grasses tolerant of sodium chloride. We have developed a cell selection technology to obtain salt-tolerant lawn grasses. A cell selection scheme with 1% sodium chloride was used. Most of the tested regenerants were more tolerant to NaCl than original plants. The descendants of the studied regenerants demonstrated the preservation of salt resistance. Most of the descendants of the regenerants Agrostis stolonifera retained high decorative qualities under salinity conditions. The tolerance remained in the next five generations. The descendants of the most salt-tolerant clones Agrostis stolonifera demonstrated resistance to 1% sodium chloride concentration in soil. These plants can serve as the basis for the creation of new salt-tolerant varieties. [ABSTRACT FROM AUTHOR]

Decreased stand uniformity together with reduced aesthetics and playability caused by annual bluegrass (Poa annua) intrusion in creeping bentgrass (Agrostis stolonifera) putting greens is one of the major problems that golf course superintendents face with managing newer playing surfaces. Few herbicides are registered for selective control of annual bluegrass in creeping bentgrass greens, and the risk of herbicide resistance remains an issue, thus use of plant growth regulators (PGRs) is still the primary method of annual bluegrass suppression. This study was conducted to evaluate eight PGR treatments, employed as a series of 15 consecutive, biweekly applications to suppress annual bluegrass encroachment in ‘Pure Distinction’ creeping bentgrass maintained as a golf course putting green in Los Angeles, CA. Best annual bluegrass suppression was observed with products containing flurprimidol (FP) at 0.256 lb/acre, paclobutrazol (PB) at 0.119 lb/acre, or three-way mixture of FP, trinexapac-ethyl (TE), and PB (FP+PB+TE) at 0.055, 0.014, and 0.055 lb/acre, respectively. Although all treatments caused some significant creeping bentgrass injury, which increased over time, PB at 0.119 lb/acre and FP+PB+TE at 0.055, 0.014, and 0.055 lb/acre, respectively, appeared to be safest among effective treatments. Additionally, those treatments caused significantly darker green turf, which may be desirable on putting greens. This research confirms the potential of PGR use to limit annual bluegrass infestation on creeping bentgrass greens in a Mediterranean climate and reveals the most effective treatments that could be used in a putting green maintenance program.

Reseeding of creeping bentgrass (Agrostis stolonifera L.) under unfavorable temperature (≈10 °C) is a common practice on golf putting greens and fairways. Seed priming to enhance germination and early emergence increases seeding success. Seed priming comparing abscisic acid (ABA), gibberellic acid (GA), glycinebetaine (GB), hydrogen peroxide (H2O2), and polyethylene glycol (PEG) has not been investigated in turfgrass. Our objective was to compare these chemical primers at three concentrations with water- and unprimed-seed at two competing germinating temperatures (10 vs. 25 °C). Two seed lots of ‘T-1’ creeping bentgrass were compared. Curve fitting of daily germination was used to compute days to 50% germination (D50) and maximum germination percentage (Gmax). Cold (10 °C) significantly inhibited emergence (higher D50) more than Gmax. The effects of primers and their rates varied with the seed lot and temperature. Enhancement of seed germination measured as early emergence (lower D50) and/or higher Gmax were only detected at 10 °C. Osmotic primers (GB and PEG) were most effective in promoting germination relative to unprimed seed followed by hormone primers (ABA and GA) with redox primers (H2O2) least effective. Glycinebetaine primed seed was the only primer effective at all concentrations, with the 100 mм concentration the only concentration to enhance germination by increasing both Gmax and early emergence (lower D50) compared with unprimed seed.

Renovation is an opportune time for golf courses to address annual bluegrass (Poa annua L.) weed populations. Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione) is an effective fumigant, but without a tarp cover, it is only effective at the highest labeled rates. Fraise mowing cultivation could be used to help remove surface material and allow practitioners to effectively fumigate at lower rates. In Summer 2018 and Summer 2019, two cool-season fairway renovation experiments were conducted in East Lansing, MI. The objective of these experiments was to assess annual bluegrass control and creeping bentgrass establishment following dazomet applications to fraise mowed surfaces. In the first experiment (fraise mowing surface disturbance experiment), dazomet was applied at a fixed rate (294 kg·ha−1) to fraise mowed plots at varying levels of surface disturbance (0%, 15%, 50%, and 100%) to a depth of 1.9 cm. In the second experiment (dazomet rate experiment), fraise mowing removed 100% of surface material at a depth of 1.9 cm and dazomet was applied at five rates (0, 294, 588, 147 + 147, and 294 + 294 kg·ha−1). Both experiments were conducted on two soils (sand topdressed vs. native) and evaluated two methods of fumigant incorporation (solid-tine cultivation vs. tillage). Five days after treatments were applied, plots were seeded with ‘Pure Select’ creeping bentgrass (Agrostis stolonifera L.). The level of fraise mowing surface disturbance had no effect on annual bluegrass emergence, and creeping bentgrass cover was poorest in native soils at the highest levels of surface disturbance. In the dazomet rate experiment, dazomet applied twice at 294 kg·ha−1 provided the most consistent control of annual bluegrass. With the exception to single applications of 294 in 2018, all dazomet treatments allowed for greater creeping bentgrass establishment than the nontreated control. Fraise mowing cultivation may simplify the removal of surface material from large areas; however, even when combined with dazomet applied at the highest rates, it fails to provide complete annual bluegrass control.

Small molecules, including H2O2 and Ca, mediate stress signaling and drought tolerance in plants. The objective of this study was to determine whether improvement in drought tolerance by H2O2 and Ca were associated with the regulation of transcription factors and stress-protective genes in perennial grass species. Plants of creeping bentgrass (Agrostis stolonifera) were sprayed with water (control), H2O2 (9 mm), or CaCl2 (10 mm) and exposed to drought stress for 20 days in controlled-environment growth chambers. Foliar application of H2O2 or Ca led to significant improvement in drought tolerance of creeping bentgrass, as demonstrated by greater turf quality, leaf relative water content, chlorophyll content, photochemical efficiency, and cell membrane stability, as compared with the untreated control. The application of H2O2 and Ca resulted in significant up-regulation of genes in Ca signaling transduction pathways [Ca-dependent kinase 26 (CDPK26), mitogen-activated protein kinase 1 (MAPK1), and 14-3-3] and transcript factors (WRKY75 and MYB13). For genes encoding antioxidant enzymes, H2O2 mainly enhanced superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and dehydroascorbate reductase (DHAR) expression, while Ca primarily improved transcript levels of SOD, monodehydroascorbate reductase (MDHAR), and GR. In addition, heat shock protein 70 (HSP70), metallothionein 1 (MT1), and glutamine synthetase 2 (GS2) were also markedly up-regulated by H2O2 and Ca under drought stress. However, the transcript level of lipoxygenase 3 (LOX3) was significantly down-regulated by H2O2 and Ca under well-watered and drought conditions. These results imply that H2O2 and Ca commonly or differentially regulate genes expression in association with drought tolerance through activating Ca signaling pathway and regulating transcription factors and stress-protective genes expression, leading to the alleviation of lipid peroxidation, maintenance of correct protein folding and translocation, and enhancement of nitrogen metabolism under a prolonged period of drought stress in creeping bentgrass.

This study aimed to elucidate the role of bacteria colonising mycorrhizal hyphae in organically bound sulfur mobilisation, the dominant soil sulfur source that is not directly plant available. The effect of an intact mycorrhizal symbiosis with access to stable isotope organo-34S enriched soils encased in 35 µm mesh cores was tested in microcosms with Agrostis stolonifera and Plantago lanceolata. Hyphae and associated soil were sampled from static mesh cores with mycorrhizal ingrowth and rotating mesh cores that exclude mycorrhizal ingrowth as well as corresponding rhizosphere soil, while plant shoots were analysed for 34S uptake. Static cores increased uptake of 34S at early stages of plant growth when sulfur demand appeared to be high and harboured significantly larger populations of sulfonate mobilising bacteria. Bacterial and fungal communities were significantly different in the hyphospheres of static cores when compared to rotating cores, not associated with plant hosts. Shifts in bacterial and fungal communities occurred not only in rotated cores but also in the rhizosphere. Arylsulfatase activity was significantly higher in the rhizosphere when cores stayed static, while atsA and asfA gene diversity was distinct in the microcosms with static and rotating cores. This study demonstrated that AM symbioses can promote organo-S mobilization and plant uptake through interactions with hyphospheric bacteria, enabling AM fungal ingrowth into static cores creating a positive feedback-loop, detectable in the microbial rhizosphere communities.

The branched-chain amino acids (BCAA) leucine (L), isoleucine (IL), and valine (V) are synthesized in plants and are essential to growth in most organisms. These compounds can be absorbed by the plant when foliarly applied, but plant catabolism of BCAA is not completely understood. A recent study observed that BCAA applied in a 2:1:1 or 4:1:1 ratio (L:IL:V) increased creeping bentgrass (Agrostis stolonifera) shoot density compared with applications of equal urea nitrogen (N) at 3.03 lb/acre N. The present study investigated whether those increases could translate to a quicker establishment rate of creeping bentgrass grown from seed in standard greenhouse pots. The BCAA applications were compared with equal N applications using urea and a commercially available amino acid product. All N treatments were applied at 3.03 lb/acre N, per application and applied a total of four times on a 14-day interval starting 14 days after seeding. Measurements included final shoot density counts and root and shoot weights, as well as digital image analysis of percent green cover for each greenhouse pot every 7 days. No differences were observed after 70 days in shoot weight, or percent green cover between BCAA treatments and urea; however, BCAA 2:1:1 and 4:1:1 increased shoot density 21% and 30%, respectively, compared with urea, and were equal to the commercially available amino acid product. Applications of BCAA 4:1:1 also increased creeping bentgrass rooting weight by a factor of 7 compared with urea N.

Amino acids have been reported to improve turfgrass growth compared with mineral nutrition; however, amino acid catabolism in plants has not been well studied. A number of turfgrass fertilizers contain amino acids; however, some amino acids may be more effective additives in fertilizers than others. Three amino acids that could be effective nitrogen sources for plant growth are the branched-chain amino acids (BCAAs). The BCAA leucine (L), isoleucine (IL), and valine (V) could be effective additives because they are nonpolar and hydrophobic, which can promote plant uptake of these compounds. Although the effect of exogenously applied BCAA on plant growth is not well known, BCAAs have been reported to increase protein synthesis in humans, and that rate of increase is related to the intake ratio of L to IL and V. The objective of this study was to evaluate the use of L, IL, and V as a nitrogen sources on creeping bentgrass (Agrostis stolonifera) and to investigate the effect of BCAAs on plant growth when all three are applied as a combination. Using specially made rooting tubes, L, IL, and V were applied in a complete factorial and compared with equal urea nitrogen at four rates, as well as an untreated control. Where all three BCAAs were applied in combination, the application ratios of 2:1:1 and 4:1:1 (L:IL:V) were tested. At 63 days after seeding, there were no differences in root length, root weight, or shoot weight; however, BCAA 2:1:1 and 4:1:1 increased creeping bentgrass shoot density by 24% and 32%, respectively, compared with equal urea nitrogen. Where shoot density was increased, nitrogen application rate had no effect. On the basis of these results, BCAAs applied in a complete combination using ratios of 2:1:1 or 4:1:1 (3.03 lb/acre N) will provide a greater creeping bentgrass shoot density compared with equal urea nitrogen.

Results suggest that sand topdressing was more consistent at reducing dollar spot (Clarireedia jacksonii) in fairway turfgrass more so than rolling. This practice could be an effective cost-saving alternative to reduce frequent fungicide applications. Research was conducted from 2011 to 2014 on a simulated golf fairway and examined dollar spot severity responses in a mixed-stand of creeping bentgrass (Agrostis stolonifera) and annual bluegrass (Poa annua ssp. reptans) to sand topdressing and rolling. Treatments consisted of biweekly sand topdressing, rolling at three frequencies (one, three, or five times weekly), a control, and three replications. Infection was visually estimated. Sand topdressing significantly (P < 0.05) reduced disease up to 50% at the peak of the dollar spot activity in 2011, 2013, and 2014. Results on the effects of rolling on dollar spot were inconsistent.

Lawns and flower are major aesthetical and environmental elements of the urban ecosystem. However, harsh urban conditions such as pollution by heavy metals are unfavorable for plants. For example, copper is toxic for ornamental plants, limiting the spread of lawn grass and flowering plants. Therefore, here we hypothesized that plants could be adapted to urban conditions by breeding. We first showed the possibility of using environmental biotechnology in urban greening to obtain, tolerating copper flowering plants and lawn grasses. We tested the adaptation of creeping bentgrass (Agrostis stolonifera L.) and painted daisy (Chrysanthemum carinatum Schousb.) to сopper. We measured Cu resistance in the next generations of those plant species. Results show that some next generations of plant regenerants have increased resistance up to 100 mg/kg Cu for Agrostis stolonifera, and up to 30 mg/kg for Chrysanthemum carinatum. Our findings thus imply that city plants may be adapted and improved by сell selection. Our approach thus represents a novel biotechnology consisting of adapting plants to pollution by сell selection. [ABSTRACT FROM AUTHOR]

Spermine (SPM) is involved in response to abiotic stress in plants, but the potential role of SPM in regulating senescence has not been well documented. Objectives of this study were to examine the effect of changes in endogenous polyamines (PAs) by SPM application on improving heat tolerance of creeping bentgrass (Agrostis stolonifera) and explore the SPM-regulated senescence associated with alterations of water and oxidative balance, photosynthesis, and heat shock proteins under heat stress. The results showed that persistent high temperature caused severe oxidative damage and significant decreases in chlorophyll (Chl) content, photosynthetic efficiency, and leaf water content leading to premature senescence in creeping bentgrass, as reflected by a significant upregulation of transcriptions of senescenceassociated genes (AsSAG39, Ash36, and Asl20). The improvement of endogenous spermidine (SPD) and SPM content induced by SPM application could significantly alleviate heat stress damage to creeping bentgrass through maintaining higher Chl content, net photosynthetic rate, photochemical efficiency, and performance index on absorption basis, promoting osmotic adjustment ability and antioxidant enzyme (superoxid dismutase, catalase, peroxidase, and ascorbate peroxidase) activities to enhance the scavenging capacity of reactive oxygen species, and upregulating transcriptions of heat shock protein (HSP) genes (HSP90-5, HSP90.1-b1, HSP82, HSP70, HSP26.7, HSP17.8, and HSP12) helping to maintain normal synthesis and functions of proteins under high temperature stress, thereby delaying heat-induced leaf senescence. These findings reveal an important role of PAs in regulating senescence in perennial plants exposed to a high temperature environment. [ABSTRACT FROM AUTHOR]

This paper is focused on the impacts of alkaline and metal deposition on soil and vegetation in the immission field of magnesium factory Jelšava-Lubeník (Slovakia). Soil samples and the foliage of vegetation were obtained from the Jelšava-Lubeník area with specific alkaline pollutants. The examined area is one of the most devastated regions of Slovakia. From the point of view of environmental regionalization, it belongs to an environmentally damaged area of Category 3. The total content of heavy metals in the soil and vegetation (Pb, Zn, Cr, Mn, Mg) were determined by atomic absorption spectrometry and X-ray fluorescence spectrometry. Soil reaction was determined in a solution of 0.01 M CaCl2. Vegetation was assessed by the Braun-Blanquet scale. In conclusion, we can say that spray particles of free magnesium oxide (MgO) strongly influence soil reaction, diversity, and vegetation cover. The research showed that the investigated sites were mostly strongly alkaline; the contents of Cr, Mn and Mg were over the toxicity limit, while the measured values of Pb and Zn did not exceed the limits set by the law. The values that measured significantly above the set limit show contamination that can be considered harmful and toxic. In the monitored species, that is, Agrostis stolonifera, Elytrigia repens and Phragmites australis, an over-limit content of Pb and Zn and toxic contents of Mg and Mn were found.

Bioremediation is an ecologically-friendly approach for the restoration of heavy metal-contaminated sites and can exploit environmental microorganisms such as bacteria and fungi. These microorganisms are capable of removing and/or deactivating pollutants from contaminated substrates through biological and chemical reactions. Moreover, they interact with the natural flora, protecting and stimulating plant growth in these harsh conditions. In this study, we isolated a group of endophytic fungi from Agrostis stolonifera grasses growing on toxic waste from an abandoned lead mine (up to 47,990 Pb mg/kg) and identified them using DNA sequencing (nrITS barcoding). The endophytes were then tested as a consortium of eight strains in a growth chamber experiment in association with the grass Festuca arundinacea at increasing concentrations of lead in the soil to investigate how they influenced several growth parameters. As a general trend, plants treated with endophytes performed better compared to the controls at each concentration of heavy metal, with significant improvements in growth recorded at the highest concentration of lead (800 galena mg/kg). Indeed, this set of plants germinated and tillered significantly earlier compared to the control, with greater production of foliar fresh and dry biomass. Compared with the control, endophyte treated plants germinated more than 1-day earlier and produced 35.91% more plant tillers at 35 days-after-sowing. Our results demonstrate the potential of these fungal endophytes used in a consortium for establishing grassy plant species on lead contaminated soils, which may result in practical applications for heavy metal bioremediation. [ABSTRACT FROM AUTHOR]

Renovation is an opportune time for golf courses to address annual bluegrass (Poa annua L.) weed populations. Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5- thiadiazine-2-thione) is an effective fumigant, but without a tarp cover, it is only effective at the highest labeled rates. Fraise mowing cultivation could be used to help remove surface material and allow practitioners to effectively fumigate at lower rates. In Summer 2018 and Summer 2019, two cool-season fairway renovation experiments were conducted in East Lansing, MI. The objective of these experiments was to assess annual bluegrass control and creeping bentgrass establishment following dazomet applications to fraise mowed surfaces. In the first experiment (fraise mowing surface disturbance experiment), dazomet was applied at a fixed rate (294 kg·ha-1) to fraise mowed plots at varying levels of surface disturbance (0%, 15%, 50%, and 100%) to a depth of 1.9 cm. In the second experiment (dazomet rate experiment), fraise mowing removed 100% of surface material at a depth of 1.9 cm and dazomet was applied at five rates (0, 294, 588, 147 + 147, and 294 + 294 kg·ha-1). Both experiments were conducted on two soils (sand topdressed vs. native) and evaluated two methods of fumigant incorporation (solid-tine cultivation vs. tillage). Five days after treatments were applied, plots were seeded with 'Pure Select' creeping bentgrass (Agrostis stolonifera L.). The level of fraise mowing surface disturbance had no effect on annual bluegrass emergence, and creeping bentgrass cover was poorest in native soils at the highest levels of surface disturbance. In the dazomet rate experiment, dazomet applied twice at 294 kg·ha-1 provided the most consistent control of annual bluegrass. With the exception to single applications of 294 in 2018, all dazomet treatments allowed for greater creeping bentgrass establishment than the nontreated control. Fraise mowing cultivation may simplify the removal of surface material from large areas; however, even when combined with dazomet applied at the highest rates, it fails to provide complete annual bluegrass control. [ABSTRACT FROM AUTHOR]

Organic layer formation in the form of thatch is a major problem in managed turfgrass systems. Biweekly application of laccase enzyme has been well-documented to facilitate the degradation of thatch and reduce the accumulation rate of organic matter in 'Crenshaw' creeping bentgrass (Agrostis stolonifera L.). A field experiment involving creeping bentgrass was conducted to evaluate the residual effects on thatch accumulation after ceasing laccase applications. A significant reduction in thatch layer thickness was observed at 6, 12, and 18 months after treatment initiation when laccase was applied at different rates and frequencies. Residual effects of laccase application were observed for thatch layer thickness, but no additional accumulation of thatch was observed 6 months after treatment cessation. At 18 months after treatment initiation, a significant increase in the thatch layer was observed where treatments had been ceased for 12 months, but no thatch accumulation was observed for laccase treatment for a second 6-month period during the second year. This information is critical to turf practitioners when developing laccase application protocols. Limiting laccase applications for a period of 6 months during 1 year was shown to be effective for thatch control. [ABSTRACT FROM AUTHOR]

Condition and quality of the lawn grass and flowering plants is important indicators of the level of landscaping and the urban environment. Copper ions significantly reduce the quality of ornamental plants. The aim of this study was to assess phytotoxicity of copper for Chrysanthemum carinatum, Festuca rubra and Agrostis stolonifera. High contamination of copper significantly limits the spread of Chrysanthemum carinatum and lawn grass. Chrysanthemum carinatum was less resistant than lawn grass to copper. Chrysanthemum carinatum can grow only with a low level of soil contamination with copper. [ABSTRACT FROM AUTHOR]

Bacterial etiolation, caused by Acidovorax avenae or Xanthomonas translucens pv. poae, is a problematic disease of creeping bentgrass (Agrostis stolonifera) and annual bluegrass (Poa annua) turfgrass stands. The objective of this study was to determine whether temperature may play a role in phytohormone production by these bacteria and to determine if there is any change in phytohormones specifically in etiolated plant tissues. In vitro, A. avenae and X. translucens were cultured at 25, 30, 35 and 40 °C for 14 days. Bacterial cultures were sampled for gibberellic acid isoforms (GA1, GA3, GA4, and GA20), jasmonic acid, salicylic acid (SA), indole-3-acetic acid (IAA), zeatin riboside, and abscisic acid (ABA). No phytohormones were detected in pure cultures of X. translucens, whereas A. avenae produced GA1, GA3, GA4, and IAA. Acidovorax avenae isolate MSU-13 produced significantly higher GA1 and GA3 at 35 and 40 °C on most days measured. In the field study, etiolated stem and leaf tissues of creeping bentgrass and annual bluegrass were evaluated for bacterial identification, etiolation ratings, and phytohormone quantification. Significantly more etiolation symptoms were observed in both annual bluegrass and creeping bentgrass on days with higher temperatures. In annual bluegrass, etiolated stems and leaves showed significantly higher GA1, GA3, etiolated leaves showed significantly higher GA20, ABA, and lower IAA compared to normal turf tissues on most experimental dates. In creeping bentgrass, higher GA1, GA4, SA, ABA, and lower IAA were detected in etiolated turf tissues than normal tissues on most experimental dates. Plant hormone regulation due to the presence of bacteria may be altered differentially in response to different bacteria species eliciting similar plant symptoms. [ABSTRACT FROM AUTHOR]