Salinity is a major abiotic stress in plant agriculture which reduces seed germination, vegetative growth, and flowering, and limits crop productivity world-wide. Salinity causes water deficit, ion toxicity, and nutrient deficiency in plants, which can result in cellular damage, growth reduction, and even death. Kentucky bluegrass (Poa pratensis L.) is the most widely used cool-season species in cool-arid climates; however it has relatively poor salt-tolerance. Thus the development of Kentucky bluegrass genotypes with increased salt tolerance is of interest to turf breeders. One impediment to selection towards this goal is finding an efficient and accurate method to evaluate the salt tolerance. The objective of this study was to examine physiological responses to salt stress and to evaluate the genetic diversity among the accessions used in the research. Salt-tolerant accessions PI371768 (768) and PI440603 (603) and salt-sensitive varieties Midnight and Baron were exposed to four levels of salinity imposed by irrigating with salt solutions of 0 dS m-1 (control), 6 dS m-1, 12 dS m-1, and 18 dS m-1 or 24 dS m-1. Soil salinity was measured using Acclima Digital TDT sensors and grass response to the stress was measured using turf quality ratings, stomatal conductance, leaf water potential and electrolyte leakage. In general, turfgrass quality, stomatal conductance, and leaf water potential decreased while electrolyte leakage increased under salinity stress. Midnight and Baron exhibited greater changes in these measurements, indicating more sensitivity compared to 768 and 603. The 6 dS m-1 treatment had little effect on the salt-tolerant accessions. Salt tolerance of 603 and 768 was confirmed and likewise, salt sensitivity of Baron and Midnight was confirmed. The genetic similarity of all cultivars used in this study was very high. All of the evaluation measurements were highly correlated, with water potential and electrolyte leakage being the most reliable and accurate methods due to the low standard deviations. Due to more repeatable methods and less user error, electrolyte leakage and turfgrass quality are recommended methods for screening salt tolerance of turfgrasses.

La apertura del dosel del bosque generada por disturbios antrópicos o naturales provoca una alteración en las condiciones ambientales del sistema ecológico, modificando la cantidad y calidad de luz, las precipitaciones, y la temperatura. Los estudios realizados en este trabajo de tesis determinaron algunos de los cambios morfo-fisiológicos que permiten el crecimiento, desarrollo y reproducción de tres especies herbáceas, Osmorhiza depauperata, Phleum alpinum y Poa pratensis, en los ambientes boscosos modificados. Estas especies aumentan su cobertura luego de la cosecha forestal, y podrían evitar la erosión del suelo, y facilitar o competir con las plántulas que podrían contribuir a regenerar el bosque. En el bosque aprovechado forestalmente mediante la prescripción de retención variable se identificaron tres situaciones donde crecieron las plantas de las especies herbáceas: dentro de la retención agregada (RA), en el borde de la retención dispersa con influencia del agregado (BRA), y en la retención dispersa (RD). Además, se seleccionaron plantas del bosque primario (BP). Por otro lado, P. alpinum y P. pratensis fueron expuestas en el invernáculo a tres niveles de radiación incidente (I4: 4%; I26: 26%; I64: 64% de la luz solar incidente fuera del bosque en los diferentes ambientes), y dos niveles de contenido de humedad del suelo (M30: 30-50% y M60: 60-80% de capacidad de campo). Las intensidades lumínicas medidas siguieron el orden: RD > BRA > RA > BP. Las plantas de todas las especies modificaron su morfo-fisiología en los distintos ambientes. Estos cambios incluyeron modificaciones en el largo de las hojas, y por consiguiente su área foliar, aumentando en los ambientes con menor radiación (BP y RA). Asimismo, en estos ambientes disminuyeron el macollaje o la cantidad de tallos. Las plantas también incrementaron la densidad de longitud de raíces en respuesta al incremento en la disponibilidad de luz. Las diferencias entre especies se podrían deber a sus hábitos de crecimiento y a la proporción de raíces finas que producen. En O. depauperata el grado de infección por micorrizas vesículo-arbusculares fue mayor que en las especies de gramíneas P. alpinum y P. pratensis. Para todas las especies se encontró que el grado de infección tendió a incrementarse al aumentar la luz, aunque solo se encontró que fue significativamente menor en BP que en el resto de los ambientes. Todas las especies produjeron mayor cantidad de biomasa por unidad de superficie iv a medida que aumentó la irradiación: el orden de las especies estuvo inversamente relacionado con el tamaño del área basal, fue mayor en O. depauperata que en P. alpinum y P. pratensis. La cantidad de inflorescencias por unidad de área basal siguió la misma tendencia que la biomasa, y no se encontraron cambios en la proporción de inflorescencias por unidad de biomasa excepto en P. alpinum. En esta especie, esta variable fue menor en BP que en el resto de los ambientes. En P. pratensis el esfuerzo reproductivo fue mayor que en O. depauperata y P. alpinum. En invernáculo se demostró que la variable más importante que modificó el crecimiento de estas plantas fue la luz. El crecimiento disminuyó considerablemente en I4. Al disminuir la irradiación aumentó la proporción de área foliar, mediante un aumento del área foliar específica y un aumento de la proporción de biomasa foliar. Al mismo tiempo, aumentó la proporción de biomasa de tallo, y disminuyó la proporción de biomasa radical. Como resultado de estos cambios, las plantas en I26 lograron mantener una tasa de crecimiento relativa similar o superior a la de I64; sin embargo, dichos cambios no fueron suficientes para mantener la tasa de crecimiento relativa en I4. Asimismo, las especies mostraron cambios típicos a nivel fisiológico: al aumentar la irradiación aumentaron la tasa máxima de fotosíntesis y el punto de compensación lumínico. Se encontraron variaciones temporales que afectaron estos valores. Al aumentar la irradiación disminuyó el contenido de clorofila tanto por unidad de área como de peso fresco, y aumentaron las relaciones clorofila a/b y carotenoides/clorofila. Todos estos resultados indican que O. depauperata, P. alpinum y P. pratensis son capaces de aclimatarse a varias situaciones ambientales. Sin embargo, O. depauperata mostró una mejor capacidad de aclimatación a niveles de irradiación muy bajos, mientras que las especies de gramíneas apenas lograron sobrevivir dado que su crecimiento fue muy lento. / Canopy openings, whether they come from anthropic or natural disturbances, might change the environmental conditions of the ecological system, modifying light quantity and quality, precipitation and temperature. Some morpho-physiological changes that determine growth, development and reproduction of the three study herbaceous species, Osmorhiza depauperata, Phleum alpinum, Poa pratensis, were evaluated in the forest, modified environments. These species increase their coverage after forest harvesting, and could prevent soil erosion, and either facilitate or compete with seedlings that could contribute to regenerate the forest. Three environments where the herbaceous species often grow were identified in a forest previously harvested following the variable retention system. They were: within the aggregate retention (RA); on the edge of the dispersed retention under the influence of the aggregate (BRA), and dispersed retention (RD). Plants were also selected from a primary forest (BP). Furthermore, P. alpinum and P. pratensis were exposed to three levels of incident radiation (I4: 4%; I26: 26%, or I64: 64% of ambient sunlight outside the forest in the various environments) and two levels of soil moisture content (M30: 30-50% or M60: 60-80% of field capacity) under greenhouse conditions. Measured light intensities showed the following order: RD > BRA > RA> BP. Plants of all species modified their morpho-physiology in the different environments. These changes included variations in blade length, and subsequently in leaf area, increasing in the environments with lower radiation (BP and RA). Also, tillering and stem numbers decreased in these environments. Plant root length density increased as light availability also increased. Species differences could be due to their growth habits and the proportion of fine roots that they produce. Vesicular-arbuscular mycorrhizae colonization was greater in O. depauperata than in P. alpinum and P. pratensis. It also tended to decrease as light availability decreased for all species. However, it was only significantly lower in BP than in the remaining environments. Increased light availability determined a greater biomass production per unit surface area in all species: the species order was inversely related to size of the basal area. It was greater in O. depauperata than in P. alpinum and P. pratensis. The number of inflorescences per unit basal area followed the same trend as biomass and no changes were found in the proportion of vi inflorescences per unit biomass, except in P. alpinum. In this species, this variable was lower in BP than in the other environments. Reproductive effort was greater in P. pratensis than in O. depauperata and P. alpinum. Greenhouse experiments showed that light was the major variable that modified growth of the study species. Growth decreased significantly in I4. Increases in specific leaf area and the proportion of leaf biomass determined an increased proportion of leaf area under lower light availability. At the same time, stem biomass proportion increased and that of root biomass decreased. As a result of these changes, plant relative growth rate was similar or greater in I26 than in I64; however, they were not enough to maintain plant relative growth rate in I4. Also, the species showed typical physiological changes: maximum photosynthetic rate and light compensation point increased as light availability also increased. Values for these variables varied with time. Chlorophyll content per unit surface and fresh weight decreased, and chlorophyll a/b and carotenoid/chlorophyll ratios increased, as light availability increased. The results obtained in this study indicate that O. depauperata, P. alpinum and P. pratensis are able to acclimate to various environmental situations. However, O. depauperata showed a better acclimation capacity than the other species to very low levels of light availability, while the grass species just were able to survive under these conditions because of their very slow growth.

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Nitrogen (N) is the most commonly over-applied nutrient in urban environments because of the large visual and growth increases. This over-application has led to an increase in the loss of N gas in the forms of ammonia and nitrous oxide, as well as an increase in nitrate leaching to surface and groundwater. Furthermore, excess N results in increased maintenance costs and landfill volume due to increased shoot growth from mowed clipping removal. Polymer coated urea (PCU) has proven to be an excellent source to these losses of N to the environment, but rate and timing parameters need study. A two-year field study, on sand and sandy loam soils in Provo, UT, was initiated in April 2014. Seven fertilized treatments included: urea split applied monthly; a single application of PCU (Agrium One Ap) applied in spring, a single PCU application in fall; two evenly split applications in spring and late summer; and three evenly split applications in spring, late summer, and late fall. These were compared to an untreated control. In addition the two application of PCU also had reduced rates of half and three-quarters, in addition to the full rate. Height and verdure measurements were taken on a weekly basis, along with periodic visual and biomass readings. All fertilized treatments resulted in a significant response to N as compared to the control. The single annual application treatments had significantly greater shoot growth during the weeks immediately after application and a significant reduction in verdure months later and, therefore, were unacceptable for consumer recommendation. Two applications of PCU, either at the three-quarter or full rates, were nearly identical in all measurements as compared to the spoon feeding of urea applied monthly. The half rate of two applications showed signs of inadequate N. Three applications of PCU was identical to two and, therefore, not recommended. This study shows two applications of PCU at the three-quarter rate is equally effective as spoon feeding the N. Doing so would result in less labor for fertilization. Further work is needed to evaluate other timing approaches for a single annual application, as well as long term effects of a reduced rate of N.

Soil contamination with heavy metals is a problem of worldwide concern that is still unsolved. The analysis of the current methods of soil cleaning from heavy metals leads to conclusions that phytoremediation, i.e. soil decontamination by using plants, is one of the best methods. Although this method has not received a wide application yet and possibilities of its application are still being analysed, it is one of the most prospective soil cleaning methods due to low cost and a rather efficient cleaning of the upper surface of soil. Three kinds of Poaceae f. Species – Lolium perenne L., Poa pratensis L. and Festuca pratensis Huds. – have been chosen in this work for decontaminating soil from heavy metals. These plants were grown under artificial laboratory conditions in soil which was once and periodically contaminated with heavy metals. It was established that it is the Lolium perenne L. that most efficiently removes heavy metals and cleans soil. The results of experiments show that the selected grassy plants (perennial ryegrass, meadow-grass and fescue-grass) efficiently clean soil from heavy metals (copper, lead, manganese, zinc, nickel and chromium) when soil contains both low (0.5–120 mg/kg) and high (up to 6,850 mg/kg) concentrations of these metals. Since the perennial ryegrass absorbs the highest amount of heavy metals, the highest efficiency of soil cleaning is achieved using this plant, therefore, 80 % of the mixture of grassy plants was formed of the perennial... [to full text] / Dirvožemio tarša sunkiaisiais metalais visame pasaulyje aktuali problema iki šiol neturinti universalaus sprendimo. Išanalizavus šiuo metu dirvožemio valymui nuo sunkiųjų metalų naudojamus metodus, galima daryti išvadą, kad vienas iš tinkamiausių metodų yra fitoremediacija, t. y. dirvožemio valymas nuo teršalų panaudojant augalus. Šis metodas dar nėra plačiai taikomas ir jo taikymo galimybės dar tik tiriamos tačiau, tai vienas iš perspektyviausių dirvožemio valymo metodų dėl sąlyginai mažos kainos ir pakankamai efektyvaus paviršinio dirvožemio sluoksnio išvalymo. Atliktų eksperimentinių tyrimų rezultatai parodė, kad pasirinkta žolinė augalija – daugiametė svidrė, pievinė miglė ir tikrasis eraičinas efektyviai valo dirvožemį nuo sunkiųjų metalų (vario, švino, mangano, cinko, nikelio, chromo) tiek esant mažoms (0,5–120 mg/kg), tiek didelėms (iki 6850 mg/kg) jų koncentracijoms dirvožemyje. Kadangi daugiausiai sunkiųjų metalų iš dirvožemio sorbuoja svidrė, tai dirvožemio valymo efektyvumas naudojant šią žolinės augalijos rūšį yra efektyviausias ir sudarant žolinės augalijos mišinį 80  sudarė svidrė ir po 10  eraičinas bei miglė. Eksperimentų metu tirta, kaip sunkiųjų metalų mišinio koncentracijos kenkia hidrobiontams ir nustatyta, kad didinat sunkiųjų metalų mišinio koncentracijas (iki 0,198–5,12 g/l) jos tampa letalinėmis vaivorykštiniam upėtakiui, tuo pačiu ir kitiems vandens gyvūnams.Pagal tyrimų su vaivorykštiniais upėtakiais rezultatus nustatyta, kad stebimų... [toliau žr. visą tekstą]

Dirvožemio tarša sunkiaisiais metalais visame pasaulyje aktuali problema iki šiol neturinti universalaus sprendimo. Fitoremediacija – naujai atsirandanti ir daug žadanti technologija nestipriai užterštiems dirvožemiams valyti naudojant augalus. Šiame darbe dirvožemio valymui nuo sunkiųjų metalų pasirinktos trys žolinės augalijos rūšys – svidrė, miglė ir eraičinas, augintos modelinėmis laboratorinėmis sąlygomis vieną kartą ir periodiškai sunkiaisiais metalais teršiamuose dirvožemiuose. Nustatyta, kad geriausiai sunkiuosius metalus iš dirvožemio sorbuoja ir didžiausias dirvožemio valymo efektyvumas pasiekiamas naudojant svidrę. Augalijai sorbuojant sunkiuosius metalus iš dirvožemio dalis šių metalų (Cu, Cr, Zn, Pb, Mn, Ni) koncentruojasi žolinės augalijos šaknyse, tačiau didžioji dalis ten susikaupiančių metalų (iki 90 proc.) pereina į antžeminę augalo dalį. Didžiausios sunkiųjų metalų koncentracijos augale (iki 60 proc. ir daugiau) ir atitinkamai efektyviausias dirvožemio valymas nustatytas svidrės atveju, todėl sudarant mišinį didžiąją dalį (80 proc.) jame sudaro svidrė. Sunkiųjų metalų mišinys daro neigiamą įtaką vaivorykštinio upėtakio jauniklių fiziologiniams ir morfologiniams rodikliams, todėl didinat sunkiųjų metalų mišinio koncentracijas (iki 0,198–5,12 g/l) jos tampa letalinėmis vaivorykštiniams upėtakiams, tuo pačiu ir kitiems vandens gyvūnams. Pagal tyrimų su vaivorykštiniais upėtakiais rezultatus nustatyta, kad stebimų upėtakių, gyvenusių akvariume, užterštame 5,7... [toliau žr. visą tekstą] / Soil contamination with heavy metals is a problem of worldwide concern that is still unsolved. The analysis of the current methods of soil cleaning from heavy metals leads to conclusions that phytoremediation, i.e. soil decontamination by using plants, is one of the best methods. Although this method has not received a wide application yet and possibilities of its application are still being analysed, it is one of the most prospective soil cleaning methods due to low cost and a rather efficient cleaning of the upper surface of soil. Three kinds of Poaceae f. Species – Lolium perenne L., Poa pratensis L. and Festuca pratensis Huds. – have been chosen in this work for decontaminating soil from heavy metals. These plants were grown under artificial laboratory conditions in soil which was once and periodically contaminated with heavy metals. It was established that it is the Lolium perenne L. that most efficiently removes heavy metals and cleans soil. The results of experiments show that the selected grassy plants (perennial ryegrass, meadow-grass and fescue-grass) efficiently clean soil from heavy metals (copper, lead, manganese, zinc, nickel and chromium) when soil contains both low (0.5–120 mg/kg) and high (up to 6,850 mg/kg) concentrations of these metals. Since the perennial ryegrass absorbs the highest amount of heavy metals, the highest efficiency of soil cleaning is achieved using this plant, therefore, 80 % of the mixture of grassy plants was formed of the perennial... [to full text]

As average global temperatures rise, cool-season C3 turfgrasses, such as the most commonly grown Kentucky bluegrass (Poa pratensis L.; KBG), struggle to tolerate extreme summer heat and increase their water consumption. Hybrid Bermudagrass (Cynodon dactylon [L.] Pers. × Cynodon transvaalensis Burtt Davy; HBG) is a warm-season C4 grass that may be increasingly suited for northern ecosystems traditionally classified as transition or cool-season climate zones. Glasshouse and field studies were conducted to compare HBG and KBG water use. The objective of the glasshouse study was to evaluate plant health and growth for two HBG cultivars (‘DT-1’ and ‘NorthBridge’) compared to a blend of KBG cultivars in all combinations of deficit, moderate, and high irrigation at optimum or short mowing height. The study was conducted in a glasshouse at Provo, UT, USA from 2020-2021. Grass was grown in pots arranged in a randomized complete block, full factorial design, with four replications of each treatment. The moderate KBG was also significantly different from both high and deficit for verdure and for the last half of NDVI. The objective of the field study was to evaluate two HBG cultivars (‘Tahoma 31’ and ‘Latitude 36’) compared to a blend of KBG cultivars for water loss and canopy health, temperature, and growth when subjected to deficit, moderate, and high irrigation. The study was arranged in a randomized complete block, full factorial design with three replications per treatment, and was conducted at Provo, UT, USA throughout the summer of 2021. In both the glasshouse and field trials, the deficit irrigated KBG consistently scored lower for NDVI and visual turf quality than all other treatments, including moderate and high KBG. This same trend was seen in the field study for percent cover. Although not observed in the glasshouse trial, it was observed in the field trial that the different irrigation levels of HBG resulted in no significant differences for any measurements but the HBG regularly scored better than KBG. The canopy temperatures of deficit irrigated KBG were also higher than all other treatments on most dates. The shoot mass, thatch mass, and total biomass of KBG were significantly less than either HBG cultivar. In the glasshouse trial it was observed that all deficit grasses were significantly lower than the other irrigation treatments and HBG had significantly deeper roots than KBG, although these results were not seen in the field trial. The data suggest that irrigation needs will be less for HBG than KBG and that HBG could provide a water-saving turfgrass alternative to KBG in semi-arid, cool-season regions with increasing water scarcity.

Annual bluegrass (Poa annua L.) and roughstalk bluegrass (Poa trivialis L.) are among the most troublesome grass weeds on golf courses throughout the United States. Herbicides for selective control of these weeds in cool-season fairways are limited and ineffective. Methiozolin is a new isoxazoline herbicide that controls annual bluegrass on putting greens and shows promise for possible weed control in fairways. Kentucky bluegrass (Poa pratensis L.) is among the most common turfgrass species used for golf fairways in the Northern United States and its response to methiozolin has scarcely been tested. A 2.5-yr field study was conducted at four Virginia locations to evaluate methiozolin efficacy for selective annual bluegrass and roughstalk bluegrass control in creeping bentgrass (Agrostis stolonifera L.) or Kentucky bluegrass fairways. Another study evaluated the response of 110 Kentucky bluegrass varieties to three rates of methiozolin. Annual bluegrass has long been presumed to impact putting green trueness, or the ability of the greens canopy to provide a smooth and directionally-consistent ball roll. Although much research has evaluated the impact of greens management on ball roll distance, no peer-reviewed research has evaluated how canopy surface factors, such as weedy annual bluegrass, will influence ball roll direction. Laboratory and field research was conducted to elucidate and overcome experimental errors that may be limiting assessment of ball directional imprecision caused by greens canopy anomalies. Techniques to minimize experimental error were employed in field studies at two Virginia golf courses to determine the influence of annual bluegrass on ball directional imprecision, bounce, and acceleration. Study results suggest that annual bluegrass patches in a creeping bentgrass putting surface can cause subtle increases in ball directional imprecision and bounce but several sources of error must be controlled before these effects can be measured. By using a mechanical putter to avoid directional errors associated with simulated-putt devices, selecting golf balls with balanced centers of gravity, eliminating legacy or "tracking" effects of repeated ball rolls via canopy brushing, and scoring ball direction 30 cm prior to terminal acceleration, we were able to detect an increase in ball directional imprecision of 8 mm m⁻¹ when balls rolled over a single patch of annual bluegrass compared to adjacent rolls on visually-pure creeping bentgrass. In herbicide efficacy studies, methiozolin-only treatments did not significantly injure creeping bentgrass or Kentucky bluegrass, reduce quality, or reduce normalized difference vegetative index regardless of application timings and rates. In general, fall applications of methiozolin reduced roughstalk bluegrass and annual bluegrass cover more than the spring-only treatments. At 1 year after the last treatment, methiozolin at 1500 g ha⁻¹ applied four times in fall at 2-wk intervals for two consecutive years controlled roughstalk bluegrass and annual bluegrass ≥85% and more consistently than other herbicides or treatment regimes. Spanning 110 Kentucky bluegrass varieties, a commercially-acceptable threshold of 30% Kentucky bluegrass injury required between 3.4 to more than 10 times the methiozolin rate needed for annual bluegrass control. Results indicate that annual bluegrass increases directional imprecision and bounce of golf balls rolling across a greens canopy. Methiozolin could be a viable herbicide for managing annual and roughstalk bluegrass in Kentucky bluegrass and creeping bentgrass fairways but weed control efficacy may be dependent on application timing. By measuring small differences in ball directional imprecision as influenced by greens canopy factors, future research efforts will aim to help turf managers choose appropriate greens management techniques. / Ph. D.