Role Of Grasses Research Articles

Goals of Restoration Ecology and the Role of Grasses in the Processes as Seen in Southeastern Africa Restoration Projects

The goals of a “restoration” programme are often not clearly defined, which may radically influence the course of the change effected by the “restoration”. In this paper, I examine many restoration studies worldwide, the goals and the practice that was followed. Grasses often play an important role in both the succession and restoration processes. In Johannesburg, South Africa, wind-blown dust caused by gold mining was a problem in the early 20th century, so the goal was to stabilise the tailings. This was achieved by establishing vegetation on the dumps or revegetation of the land on which the tailings were deposited. Stabilisation of the Cape Flats was the goal in the late 19th century to allow easy movement along sandy roads in the region and marram grass was introduced from Europe specifically for this purpose. Revegetation with a different vegetation type is often a logical option where land use is of paramount importance. Replacement with crop plants or grasses is where the previous vegetation is replaced by an alternative land use that will be of benefit to the local people. The terms “rehabilitation” and “restoration” are often used interchangeably. Early researchers on the subject pointed out that rehabilitation is on the trajectory to full restoration or the original former state of the degraded site. In this review, the rehabilitation processes are discussed following dune mining in South Africa and at sites in Mozambique.

Impact of environmental factors on the epidemiology of eosinophilic esophagitis in southwestern Europe (2007-2020).

Eosinophilic esophagitis (EoE) is a disease characterized by symptoms of esophageal dysfunction and at least 15 eosinophils/hpf in the esophagus. Other systemic and local causes of esophageal eosinophilia should be excluded. The study objectives were to examine the annual epidemiology of EoE for 14 consecutive years, investigate whether there is a relationship between the count of aeroallergens and the incidence of EoE for 12 years, evaluate whether there are family ties between the patients with EoE, and determine whether there are cases of EoE that are triggered or exacerbated by pollens. We conducted a prospective, descriptive, and analytic study in patients with EoE for 14 years (2007-2020). The study variables were age, sex, relatives with EoE, time of evolution of the symptoms until diagnosis of the disease, and symptoms. We examined incidence and prevalence, annual counts of aeroallergens for 12 years, and number of diagnoses per year (in 2007-2020). We studied patients with active EoE (in April-July) and EoE in remission (in August-March) for 2 consecutive years. Exacerbations were investigated by measuring symptoms using a visual analog scale of 1 to 10. Of the 366 patients with EoE (studied from 2007 to 2020), 83.5% were atopic, with respiratory allergy and 28% had a food allergy. Their mean age was 35 years. The time of evolution of the symptoms was more than 6 years. Only 11% of the patients had a degree of kinship. Of the 366 patients, 87% had dysphagia, 27% had had impactions, and 12.5% had other symptoms of esophageal dysfunction. We found a positive correlation between the incidence of EoE and Platanaceae pollens. We did not detect any case of EoE triggered or exacerbated by pollens. The epidemiology of EoE in southwestern Europe continues to grow. We have corroborated the relevant impact of the environment on genetics. Future studies will clarify the possible relevance of Platanaceae pollens in the increased epidemiology of EoE. The role of grass and Oleaceae pollens in triggering EoE is limited by having a short pollination in time.

Using cover crops to offset greenhouse gas emissions from a tropical soil under no-till

AbstractCrop rotations under no-till (NT) have been a strategy to increase soil organic carbon (SOC) and mitigate greenhouse gas (GHG) emissions, enhancing the cropping system efficiency. However, there is still controversy on the role of grasses and legumes, and species diversity and their impacts. This study aimed to assess the GHG emissions, SOC, and Nitrogen (TN) in a soybean production system managed under NT in rotation with different species in the fall–winter and the spring seasons. Main plots during the fall–winter were (1) Triticale (x Triticosecale) and (2) Sunflower (Helianthus annuus). Subplots established in the spring were (a) Sunn hemp (Crotalaria juncea), (b) Sorghum (Sorghum bicolor), (c) Pearl millet (Pennisetum glaucum), plus a (d) Fallow treatment. Soybean was grown every year in the summer, in sub-subplots. The GHG emission was affected according to crop species. In the spring, Sunn hemp emitted more nitrous oxide (N2O) (0.82 kg ha−1) than fallow (0.58 kg ha−1); however, the high C and N inputs by the legume and also other cover crop residues reduced the relative emissions compared with fallow. Growing pearl millet or Sunn hemp as a spring cover crop increases SOC by 7% on average compared with fallow. The N2O emission of Sunn hemp accounted for only 0.28% of the total N accumulated in the legume residues, notably lower than IPCC estimates. In the fall–winter, Triticale increased SOC by 7%, decreased CO2 emission by 18%, and emitted 20% lower GHG to produce the same soybean yield compared with sunflower. Soybean rotation with triticale in fall–winter and Sunn hemp or pearl millet in spring decreases GHG emissions. Our results indicate that the right choice of species in rotation with soybean under NT increases SOC and may offset GHG emissions from tropical soils. It may be an important tool in mitigating potential global warming.

Grasses as a refuge for Fusarium circinatum L. – evidence from South Africa

Fusarium circinatum L. is an important pathogen in countries that grow and manage Pinus species. Approximately 50% or 600 000 ha of South Africa’s commercial plantations are planted to Pinus spp. and some of these are threatened by this fungus. Contaminated plants, planting trays, soil and water can all act as sources of inoculum. In this study, we considered the role of grasses as a possible source of inoculum for F. circinatum-associated disease of Pinus in South Africa. Isolates of F. circinatum were collected from grasses in the understories of pitch-canker affected stands of Pinus radiata D.Don and Pinus patula Schiede ex Schltdl. & Cham. in the Western Cape and Limpopo provinces, respectively. The mating types and microsatellite-based genotypes of the isolates were then compared with those in collections of this pathogen associated with pitch-canker on P. radiata and P. patula in the respective regions. The results showed that the F. circinatum isolates from grass originated from inoculum produced from stem and branch cankers on the trees above the grasses. The discovery of F. circinatum from five grass species in Limpopo increases the total number of known grasses associated with the fungus to nine in South Africa and seventeen globally. All of the F. circinatum isolates recovered from grass in South Africa displayed levels of aggressiveness to P. patula seedlings that were comparable with those of an isolate used for routine screening of commercial planting stock. The data also suggest that grass might influence the expression of disease caused by F. circinatum on Pinus. This was because a specific genotype of the pathogen originating from grass was less aggressive on P. patula seedlings than its counterpart from diseased Pinus. Taken collectively, the results indicate that phytosanitary practices for the management of F. circinatum should include grass as a significant source of inoculum, and this should be an important quarantine consideration, both nationally and internationally.

The Role of Grass vs. Exogenous Abrasives in the Paleodietary Patterns of North American Ungulates

The attainment of high crowned teeth (hypsodonty) has often been thought to be associated with grazing because many abrasive opal particles are known in grass that are presumed to wear down mammalian teeth. Equids have often been discussed regarding tooth morphological change due to the evolution of highly hypsodont teeth over time, the hyper-grazing habits of modern horses, and the originally-held view that the acquisition of hypsodonty and the widespread appearance of grasslands were synchronous. Recent studies, however, have reported asynchrony in the origin of hypsodonty and the widespread appearance of grasslands and have considered exposure to exogenous grit as important evolutionary drivers of hypsodonty in ungulates. We tracked changes in crown height (hypsodonty index), relative abrasion (mesowear) and food and grit scar topography on dental enamel (microwear) to examine the relative contributions of grass versus grit as a driving force in ungulate tooth changes during the evolution of North American Equidae compared to four North American ruminant artiodactyl families (Camelidae, Antilocapridae, Dromomerycidae, and Merycoidodontidae). We found that the overall pattern of the timing of the attainment of hypsodonty is inconsistent with grazing as the main impetus for the “Great Transition” within equids nor within the artiodactyl families as highly hypsodont ungulates post-date the spread of widespread grasslands. Mesowear closely mirrored hypsodonty trends in all families. Microwear patterns, particularly high degrees of enamel pitting (particularly large pits) and unusually coarse scratch textures in all five families, are consistent with exposure to exogenous grit as the main driver of hypsodonty acquisition prior to the consumption of significant levels of grass. Equidae exhibited a wider array of dietary behavior than the other families through most of their evolutionary history. Even so, grass was a much more common dietary item for equids than for the other families, and when combined with exogenous grit, which was more accelerated from the early Miocene onward based on more pitting and coarser scratch textures, may explain the more extreme acquisition of hypsodonty in equids compared to the artiodactyl families studied and set the stage for the Equidae alone to become hypergrazers in the Recent.

Evaluating the Capability of Grass Swale for the Rainfall Runoff Reduction from an Urban Parking Lot, Seoul, Korea.

This field study elaborates the role of grass swale in the management of stormwater in an urban parking lot. Grass swale was constructed by using different vegetations and local soil media in the parking lot of Mapu-gu Seoul, Korea. In this study, rainfall runoff was first retained in soil and the vegetation layers of the grass swale, and then infiltrated rainwater was collected with the help of underground perforated pipe, and passed to an underground storage trench. In this way, grass swale detained a large amount of rainwater for a longer period of time and delayed peak discharge. In this field study, various real storm events were monitored and the research results were analyzed to evaluate the performance of grass swale for managing rainfall runoff in an urban area. From the analysis of field experiments, grass swale showed the significant rainfall runoff retention in different rain events. Grass swale markedly reduced total rainfall runoff volume and peak flow during the small storm events of intensity about 30 mm/h. From the analysis, on average rainfall runoff retention from the grass swale was found around 40 to 75% during the various small rain events. From the results, we can say that grass swale is a stormwater mitigation practice which can help avoid flash flooding problems in urban areas.

Exploring the potential role of grasses in South African traditional medicine

Exploring the potential role of grasses in South African traditional medicine

Sediment record from the Kamyshovoe Lake: history of vegetation during late Pleistocene – early Holocene (Kaliningrad District, Russia)

Newly obtained pollen and diatom data from the Kamyshovoe Lake (germ. Dobauen, Vishtynets Highland, Baltic Uplands) controlled by radiocarbon dating allowed to reconstruct the history of local vegetation during late Pleistocene – early Holocene. Pollen records show the formation of birch-predominating forest at ca. 13.4 ka cal. BP and the flourishing of pine towards the second half of the chronozone since about 13.2 ka cal. BP. The transition to the Younger Dryas around 12.7 ka cal. BP led to the development of sparse shrub tundra with Juniperus and communities of steppe herbs. Amelioration of the environmental regime enabled birch and pine woods to spread during the second part of GS-1 event and the Preboreal. The late Preboreal time is marked by the appearance of Populus and an increase in the role of grasses in the vegetation cover, which can be correlated to similar open vegetation phases deduced from other pollen records in Europe (11.3–11.1 ka cal. BP). During the Boreal (since ca. 10.0 ka cal. BP) Corylus had its maximum value, Alnus, Tilia and Quercus appeared and spread while the birch-pine forests retreated.

Grassland species differentially regulate proline concentrations under future climate conditions: an integrated biochemical and modelling approach.

Summary Proline (Pro) is a versatile metabolite playing a role in the protection of plants against environmental stresses. To gain a deeper understanding of the regulation of Pro metabolism under predicted future climate conditions, including drought stress, elevated temperature and CO 2, we combined measurements in contrasting grassland species (two grasses and two legumes) at multiple organisational levels, that is, metabolite concentrations, enzyme activities and gene expression.Drought stress (D) activates Pro biosynthesis and represses its catabolism, and elevated temperature (DT) further elevated its content. Elevated CO 2 attenuated the DT effect on Pro accumulation.Computational pathway control analysis allowed a mechanistic understanding of the regulatory changes in Pro metabolism. This analysis indicates that the experimentally observed coregulation of multiple enzymes is more effective in modulating Pro concentrations than regulation of a single step. Pyrroline‐5‐carboxylate synthetase (P5CS) and pyrroline‐5‐carboxylate reductase (P5CR) play a central role in grasses (Lolium perenne, Poa pratensis), and arginase (ARG), ornithine aminotransferase (OAT) and P5CR play a central role in legumes (Medicago lupulina, Lotus corniculatus).Different strategies in the regulation of Pro concentrations under stress conditions were observed. In grasses the glutamate pathway is activated predominantly, and in the legumes the ornithine pathway, possibly related to differences in N‐nutritional status.

Research Article: Fluorine uptake by cultivated and uncultivated grasses: implications for co-evolution between grasses and grazers

Abstract Fluorine has no known physiological role in grasses, yet is an essential nutrient for grazing animals. The evolution of an uptake mechanism for F must be examined in the context of the coevolution of grasses and grazers. The objective of this study was to determine whether uncultivated grasses buffer the uptake of F in a range acceptable for grazing animals and whether cultivated grasses have lost this buffering mechanism. The uncultivated grasses big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium (Michx.) Nash) and switchgrass (Panicum virgatum L.), and the cultivated grasses wheat (Triticum aestivum L.), rye (Secale cereale L.) and oats (Avena sativa L.), were grown in a greenhouse and watered with NaF at F concentrations in the range 0–9 mg/kg. Total F concentrations of plant shoots were determined by the alkali-fusion method. Average F contents for uncultivated grasses (29 mg/kg for big bluestem, 26 mg/kg for little bluestem, 25 mg/kg for switchgrass) were bel...

Improved turf quality of transgenic bahiagrass (Paspalum notatum Flugge) constitutively expressing the ATHB16 gene, a repressor of cell expansion

Bahiagrass (Paspalum notatum Flugge) is a popular low-input turfgrass in subtropical regions. However, its turf quality and widespread use as residential turf is limited by up to 60-cm-tall seedheads and its open, sparse-looking growth habit. Plant growth retardants (PGRs) are being used in bahiagrass for the suppression of seedheads and leaf growth since a dwarf bahiagrass cultivar is not available and mowing costs are increasing. However, PGRs have to be applied frequently and may result in phytotoxicity. The improvement of turf quality by genetic engineering represents a promising alternative to the application of PGRs. The data presented here indicate that over-expression of the Arabidopsis ATHB16 transcription factor in bahiagrass significantly changes plant architecture of this important low-input turfgrass. All transgenic plants investigated produced significantly more vegetative and fewer reproductive tillers, shorter leaves and shorter tillers. Over-expression of ATHB16 resulted in a proportional reduction of leaf width and leaf length. The formation of seedheads under natural photoperiod was delayed in some transgenic lines for approximately 4 weeks. Total root or shoot biomass and seed set were not compromised in semi-dwarf bahiagrass plants over-expressing ATHB16. Our findings are consistent with the proposed function of ATHB16 as a suppressor of cell expansion and demonstrate its conserved role in grasses with direct practical implications for enhancing turf quality.

Role of grass like species on the aquatic habitat management

Role of grass like species on the aquatic habitat management

Establishment, Distribution, and Pathogenicity of Puccinia striiformis f. sp. tritici in South Africa.

Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks., has become an endemic disease of wheat (Triticum aestivum L.) in South Africa since it was first observed near Moorreesburg, Western Cape during August 1996. The main objectives of this study were to monitor the occurrence, spread, and the possible development of new variants of the stripe rust pathogen and the susceptibility of grass species to the pathogen. Results of surveys conducted during 1996 to 1999 revealed that rainfed wheat produced in the Western Cape, Eastern Cape, and the eastern Free State, as well as irrigated wheat produced in KwaZulu-Natal and the Free State, are most likely to be affected by stripe rust epidemics. Pathotype 6E16A- with virulence to Yr2, Yr6, Yr7, Yr8, Yr11, Yr14, Yr17, and Yr19 and pathotype 6E22A- with added virulence to Yr25 were detected. The occurrence of pathotype 6E22A- is currently restricted to KwaZulu-Natal and the Free State. Stripe rust isolates found on Hordeum murinum L. in the Western Cape were identified as pathotype 6E16A-, and both pathotypes 6E16A- and 6E22A- were collected from Bromus catharticus Vahl (= B. unioloides H.B.K.) in the eastern Free Sate. Urediospores from infections similar to stripe rust found on the grass species Dactylis glomerata L. (Eastern Cape), Poa pratensis L. (= P. bidentata Stapf; Western Cape), and P. annua and P. triviales L. (eastern Free State) failed to infect wheat cv. Morocco seedlings in the glasshouse. The possible role of grasses in the over-summering of the stripe rust pathogen has not yet been established. Stripe rust infections, however, have been found on summer-sown wheat in the south Western Cape during 1998, volunteer wheat growing in the summer and autumn months in the eastern Free State from 1998 to 2000, and on summer-sown wheat in Lesotho.

Lignin-carbohydrate complexes in forages: structure and consequences in the ruminal degradation of cell-wall carbohydrates.

Lignin-carbohydrate complexes (LCCs) are recognised as key structures in forage degradability. Apart from ester bonds involving phenolic acids, which seem to play a major role in grasses, little is known about the other types of linkages that must exist but have proved difficult to demonstrate. The chemical nature of possible LCC linkages is presented and the various mechanisms through which LCCs in the cell-wall architecture may interfere with carbohydrate utilisation by rumen microorganisms are discussed.

THE CONTROL OF TILLERING IN GRASSES BY AUXIN

THE PHENOMENON of tillering, which is the development of axillary buds of grass plants into branch shoots or tillers, has been shown to be affected by nutrition, soil moisture, seed size, competition, injury, day-length, temperature, depth of planting and transplanting (cf. review of Gardner, 1942). In the light of the work of Thimann and Skoog (1933, 1934) on the inhibition of buds of Vicia Faba by auxin, it would seem likely that tillering in grasses would be controlled by auxin just as branching in dicotyledonous plants is. The following experiments represent an attempt to test this view. METHODS.-Experiments were carried on with plants of two grasses, Wintex barley and Chalco teosinte, grown in a rich garden soil in a greenhouse during the fall and winter months in conjunction with experiments on flowering reported elsewhere (Leopold and Thimann, 1949). Both of these grasses form tillers abundantly in the field. The plants were germinated and grown in a 16hr. day except where other day-lengths are specified. Daylight was extended to 16 hr. by the use of filament lights and in some cases shortened to 10 hr. by the use of double cloth curtains. Night temperatures were kept above a minimum of 18?C. At the age of 3-5 weeks, groups of ten plants were given each of the treatments described. Various water-soluble chemical agents were applied to the plants through the leaves. The youngest mature leaf was cut off about half way down the blade, and the stump was introduced into a small vial containing 1 ml. of the solution being applied. The solution was generally entirely taken up by the plant within 7 days. Control plants in each experiment were treated with similar amounts of water alone. Three or 4 weeks after treatment each plant was dissected and the number of tillers counted. For the purposes of this study, a tiller is defined as an elongated lateral bud which has developed sufficiently to turn leaf-green. Ordinarily not more than two tillers were formed per plant under the conditions of the experiments. EXPERIMENTS.-The role of the apical bud.Since the apical buds are normally the source of the auxin which inhibits lateral buds in dicotyledonous plants, it would seem likely that apical buds might play the same role in grasses. If this is the case, then removal of the apices should cause tillering, and substitution of auxin for the apices should prevent tillering. Apical buds were therefore destroyed in situ with a needle in twenty plants each of teosinte and of barley. Half of these were then injected in the position of the apex by means 1 Received for publication October 8, 1948. It is a pleasure to acknowledge the help of Professor K. V. Thimann in the organization of the study and preparation of the manuscript. of a hypodermic needle with about 0.1 ml. of solution containing 400 mg. per liter of a-naphthaleneacetic acid. The injection was repeated at weekly intervals for 3 weeks. The number of tillers produced after the fourth week is shown in table 1.