Paspalum Urvillei Research Articles

Discovery of natural Paspalum L. (Poaceae) triploid hybrids near sympatric populations of Paspalum urvillei Steud. and species of Paniculata group in northeastern Argentina

Discovery of natural Paspalum L. (Poaceae) triploid hybrids near sympatric populations of Paspalum urvillei Steud. and species of Paniculata group in northeastern Argentina

Alternative Evolutionary Pathways in Paspalum Involving Allotetraploidy, Sexuality, and Varied Mating Systems.

The genetic systems of Paspalum species have not been extensively studied. We analyzed the ploidy, reproductive mode, mating system, and fertility of four Paspalum species-Paspalum durifolium, Paspalum ionanthum, Paspalum regnellii, and Paspalum urvillei. An analysis of 378 individuals from 20 populations of northeastern Argentina was conducted. All populations of the four Paspalum species were pure tetraploid and had a sexual and stable reproductive mode. However, some populations of P. durifolium and P. ionanthum showed low levels of apospory. Populations of P. durifolium and P. ionanthum had low seed sets under self-pollination but were fertile under open pollination, showing that self-incompatibility likely caused self-sterility. In contrast, populations of P. regnellii or P. urvillei showed no evidence of apospory, and seed sets in both self- and open pollination conditions were high, suggesting that they are self-compatible due to the absence of pollen-pistil molecular incompatibility mechanisms. The evolutionary origin of the four Paspalum species could explain these differences. This study supplies valuable insights into the genetic systems of Paspalum species, which could have implications for their conservation and management.

A vegetation classification and description of Telperion Nature Reserve, Mpumalanga, South Africa

Aims: This study identified, classified and mapped the different plant communities found on the Telperion Nature Reserve. Study area: Telperion Nature Reserve, Mpumulanga, South Africa. Methods: Using a 1:10,000 aerial photograph, Telperion was delineated into homogenous physiognomic-physiographic units. 294 sample plots (100 m2) were placed in a randomly stratified manner within identified homogenous units. Plant species present in sample plots were recorded and allocated a modified Braun-Blanquet cover abundance scale value. Sample plot data were captured into TURBOVEG and exported for editing, classification and processing in JUICE. A modified TWINSPAN classification was applied to derive a first approximation of the plant communities in a synoptic table that was refined using Braun-Blanquet procedures. Species were manually arranged into groups. Diagnostic, constant and dominant species were statistically determined from the synoptic table. Threshold values for fidelity, frequency and canopy cover were set and a final phytosociological table was produced for describing the plant species composition for the different plant communities. Results: 22 plant communities were identified for Telperion. Five were major communities, 14 were sub-communities and 13 were variants. The five major plant communities were Cyathea dregei–Ilex mitis ravine woodland, Paspalum urvillei–Phragmites australis valley bottom wetland, Diospyros lycioides–Combretum erythrophyllum riparian woodland, Eragrostis curvula–Seriphium plumosum midslope plateau grassland, and Combretum molle–Englerophytum magalismontanum rocky ridge woodland. The plant communities were also described and mapped. Conclusions: The classification, description and mapping of Telperion’s vegetation provides a basis for management decision making about wildlife stocking rates, fire planning, and vegetation management. Findings indicate that Bankenveld vegetation is heterogeneous with a variety of habitats including woodland and grassland components. Telperion has a variety of plant communities and a high plant species diversity, making it a reservoir for plant species and an important conservation area. Taxonomic reference: SA-Plant Checklist-2019–2020, South African National Biodiversity Institute, 2020, Botanical Database of Southern Africa (BODATSA) (http://posa.sanbi.org/) [accessed January 2022]. Abbreviations: BB = Braun-Blanquet; m a.s.l. = metres above sea level; TWINSPAN = Two-way indicator species analysis.

Paspalum urvillei (Vasey grass)

This datasheet on Paspalum urvillei covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.

Cinética de absorção de potássio em espécies de gramíneas forrageiras nativas do bioma Pampa

ABSTRACT: This study quantified K uptake kinetic parameters in grass species Paspalum notatum, Paspalum urvillei and Axonopus affinis to associate them with growth. Ten milliliters (10 ml) of nutrient solution were collected in two-liter pots - with five repetitions in 24 hours - in order to determine K concentrations in the samples. Shoot and root dry matter, root length, volume, diameter and surface area, as well as kinetic parameters associated with nutrient uptake (Vmax, Km, Cmin and I) were determined. Species P. notatum was the one presenting the highest root, shoot and total dry matter production, as well as the highest root volume. P. urvillei recorded the highest K content, which may be associated with thinner roots and greater root surface area. A. affinis recorded the highest Vmax value, which led to greater K uptake efficiency.

In-situ assessment of soil-root bonding strength to aid in preventing soil erosion

Research shows that construction of seawalls controls soil erosion along the coastal lines but scouring at the bottom deteriorates water clarity and causes algae growth. An environmentally friendly, sustainable solution such as controlled cultivation of plants has potential to perform better in such cases. Studies already show that plant roots’ tensile strength has direct influence on soil shear strength. However, the tensile strength tests performed in the lab cannot represent the exact ambient condition. This paper describes the development of a novel, effortless approach to carry and assemble an In-situ Smart Testing Apparatus (ISTA) that evaluates Soil Root Bonding Strength (SRBS) by pulling vegetation with roots out of the soil and measures and records the pulling strength along with the vertical displacement that takes place during the uprooting process. Another aspect of the equipment includes in-situ tensile testing capability of plant roots. In addition to those, the controlling program of the equipment stores other parameters like test date and time along with the latitude, longitude, humidity, and temperature of test location in the same file. This paper includes the initial study conducted on four different naturally grown species (Ranunculus acris, Stenotaphrum secundatum, Paspalum urvillei, and Rhynchospora mixta) using the developed ISTA near a pond at the Agricultural Department at Louisiana Tech University. Different forces required to uproot the investigated plants indicate that SRBS could be stimulated by the types and arrangements of roots inside subsoil. The obtained results reveals a strong effect of plant types and soil phase properties (soil bulk density, moisture content, air content, and pore space) on SRBS in the form of pulling force and displacement. The ISTA, thus, has significant potential to measure, store and distribute the real time data that can aid relevant professionals in preventing soil erosion and ensuring sustainable coastal ecosystems.

Understanding photosynthetic and metabolic adjustments in iron hyperaccumulators grass

Setaria parviflora and Paspalum urvillei are iron hyperaccumulating species. In order to understand how they are iron resistant, this study evaluated the adjustments in photosynthetic apparatus, metabolic pathways, and antioxidant response after exposure to iron excess. Two assays were carried out with different purposes. S. parviflora and P. urvillei were grown in Hoagland & Arnon nutrient solution containing 0.009, 1, 2, 4 and 7 mM Fe-EDTA to evaluate which Fe concentration causes accumulation of this element above the toxicity threshold. In addition, leaf samples were collected from plants growing in 0.009 and 7 mM iron-EDTA solution on the 6°, 10°, 14° and 18° day of growth in order to evaluate the adjustments in terms of primary metabolite concentrations and the antioxidant capacity. Only the 7 mM iron-EDTA treatment caused a toxic iron accumulation in the shoot of both species. P. urvillei had decreased photosynthetic rate only upon exposure to 7 mM iron-EDTA, in addition, adjustments in the electron transport rate through photosystem II and oxidation state of quinones were observed. Meanwhile, S. parviflora presented a gradual reduction in photosynthetic rate, although with higher non-photochemical quenching of fluorescence values. P. urvillei showed inhibition of tricarboxylic acid cycle. Based on the activity of antioxidant enzymes, S. parviflora showed higher ascorbate peroxidase, peroxidase values, and lipid peroxidation. We additionally identified that malate can also function to neutralize the free-reactive Fe and may contribute to the tolerance mechanism in P. urvillei. Therefore, these species have the ability to accumulate high concentrations of iron within a few days using effective and different adjustments in photosynthetic, antioxidant and carbon metabolism to cope with iron excess.

Understanding the extent of phenotypic variability in accessions of Paspalum urvillei Steud. from the USDA NPGS

The objective of this study was to investigate the phenotypic variability in Paspalum urvillei Steud. related to twelve zootechnical traits to better understand the diversity of 41 accessions from the USDA GRIN platform from seven countries. First, we performed a structure inference based on the phenotypic data, identifying two structure groups, and the majority of Brazilian accessions belonged to the first group. Then, we performed principal component analysis and principal coordinate analysis, making Violin plots for each trait within each structure group. Next, we performed spatial clustering of the accessions and utilized an unweighted pair group method with arithmetic mean clustering. In brief, the Brazilian P. urvillei breeding programs may be successful by importing USDA germplasm resources from the second phenotypic structure group.

Paspalum urvillei and Setaria parviflora, two grasses naturally adapted to extreme iron-rich environments

Paspalum urvillei and Setaria parviflora are two plant species naturally adapted to iron-rich environments such as around iron mines wastes. The aim of our work was to characterize how these two species cope with these extreme conditions by comparing them with related model species, Oryza sativa and Setaria viridis, that appeared to be much less tolerant to Fe excess. Both Paspalum urvillei and Setaria parviflora were able to limit the amount of Fe accumulated within roots and shoots, compared to the less tolerant species. Perls/DAB staining of Fe in root cross sections indicated that Paspalum urvillei and Setaria parviflora responded through the build-up of the iron plaque (IP), suggesting a role of this structure in the limitation of Fe uptake. Synchrotron μXRF analyses showed the presence of phosphorus, calcium, silicon and sulfur on IP of Paspalum urvillei roots and μXANES analyses identified Fe oxyhydroxide (ferrihydrite) as the main Fe form. Once within roots, high concentrations of Fe were localized in the cell walls and vacuoles of Paspalum urvillei, Setaria parviflora and O. sativa whereas Setaria viridis accumulated Fe in ferritins. The Fe forms translocated to the shoots of Setaria parviflora were identified as tri-iron complexes with citrate and malate. In leaves, all species accumulated Fe in the vacuoles of bundle sheath cells and as ferritin complexes in plastids. Taken together, our results strongly suggest that Paspalum urvillei and Setaria parviflora set up mechanisms of Fe exclusion in roots and shoots to limit the toxicity induced by Fe excess.

PSIV-10 Preference evaluation of plant functional types grasses in calves

Abstract The functional types of plants (PFT) ecological approach could be used to link the preferences of ruminants. In order to investigate if ruminant preferences were associated with this approach, three PFT groups were evaluated. A group “B”, represented by Paspalum urvillei (PU-B), “C” by Nassella neesiana (NN-C) and Sporobolus indicus (SI-C) and “D” by Andropogon lateralis (AL-D). In a randomized block design with repeated measures over time, two independent cafeteria trials (autumn-winter, A-W, and spring-summer, S-S) were carried out in calves (n = 8 for A-W; n = 4 for S-S; BW=240–270 kg) arranged in four pens. In three sessions of ten minutes each, calves received 120–160 gDM of fresh cut leaves from the different species. Dry matter intake (DMI), nitrogen intake (NI) and neutral detergent fiber intake (NDFI) were measured. Data were analyzed with a mixed model that included specie and session as fixed effects and blocks as a random. The statistical analyses were performed with SAS (University Edition), data is expressed as lsmeans and was considered to differ when Tukey test presented P < 0.05. No significant differences were observed between sessions. The DMI and NI were higher in NN-C and lower in AL-D (P < 0.01) during A-W. However, in S-S, higher DMI and NI were observed in AL-D and SI-C while NN-C presented the lower DMI and NI (P < 0.01). The FDNI did not show differences in A-W meanwhile in S-S was positively associated with DMI (Table1). Interestingly, when the season changed, it was observed a change in PFT preference, in A-W calves preferred NN-C whereas in S-S preferred AL-D. However, attributes associated with preferences were maintained in both stations, for instance, higher DMI was associated with higher NI. Additional research is required on the interactions between PFT approach and the preference of animals for different species.

Tests of Hexazinone and Tebuthiuron for Control of Exotic Plants in Kauai, Hawaii

Non-native plant species have become serious pests in Hawaii’s delicate island ecosystems. It is necessary to control invasive plants. The herbicides hexazinone and tebuthiuron were evaluated for defoliation efficacy to control several major invasive plants and for non-target effects on native plants at Site I in a rainforest at 1200 m elevation and Site II in a mesic area at 640 m elevation on the island of Kauai, Hawaii. The invasive weed species in the sites included daisy fleabane (Erigeron karvinskianus DC.), faya tree (Myrica faya Ait.), strawberry guava (Psidium cattleyanum Sabine), banana passion fruit (Passiflora mollissima Bailey), vaseygrass (Paspalum urvillei Steud.), and highbush blackberry (Rubus argutus Link. 1822). Native plants included ohia lehua (Metrosideros polymorpha Gaudich.), naupaka (Scaevola cerasifolia Labill.), pilo (Hedyotis mannii), hona (Urera glabra (Hook. & Arn.)), aalii (Dodonaea viscosa Jacq.), and amau (Sadleria sp.). The results showed that broadcast applications of hexazinone granules and tebuthiuron pellets were effective on some of those invasive species. Herbicidal tolerance varied among the native species. For example, D. viscosa showed high tolerance to hexazinone. S. cerasifolia was susceptible to hexazinone, but not to tebuthiuron. The inconsistent defoliation of Sadleria sp. occurred among different applications rates of the two herbicides. M. polymorpha, particularly when it was small, could tolerate hexazinone and tebuthiuron. U. glabra was severely injured by the two herbicides. H. mannii was moderately tolerant to hexazinone, but fairly sensitive to tebuthiuron. The invasive loblolly pine (Pinus taeda L.) was highly tolerant to hexazinone, but was very sensitive to tebuthiuron. M. faya was very sensitive to hexazinone, but very tolerant to tebuthiuron. P. cattleyanum was sensitive to both herbicides. Six and nine months after hexazinone and tebuthiuron treatment, respectively, native plants were transplanted into the Sites to observe injury from residual herbicides. Approximately less than 10% mortality was observed for the out-planted native species three months after planting (MAP), indicating that the native species showed less injury in the early period of transplant. The mortality of the three endangered species Kauai hau kuahiwi (Hibiscadelphis distans), Kauai delissea (Delissea rhytidosperma H.Mann) and kawawaenohu (Alsinidendron lynchnoides), however, increased as the MAP increased. Overall, broadcast treatments of hexazinone and tebuthiuron at rates higher than 1 kg active ingredient per hectare would be problematic. The dissipation half-life values of hexazinone and tebuthiuron in the 1-15 cm layer of soils at the two sites were approximately 7 days and greater than 180 days, respectively.

Allelopathy in Poaceae species present in Brazil. A review

Allelopathy is an important ecological mechanism in natural and managed ecosystems. Its study is critical to understand natural plant behaviors, to isolate allelochemicals with herbicide potential, and to use the allelopathic genes in transgenic studies. Poaceae is an ecologically dominant plant family and it is economically important worldwide because its chemical diversity represents an important source to discover new molecules. From this viewpoint, Brazil is an interesting place to study, encompassing 197 genera of the Poaceae family, many of them being dominant in various biomes and some being native to Brazil. Here, we review the literature describing allelopathic activities involving grasses of the Poaceae family. We evaluate the experimental conditions used in these studies, we identify the allelochemicals involved, and, finally, we assess the applicability of allelopathy. Our main findings are (1) among the 47 Brazilian species studied for their allelopathic effects, only Bothriochloa barbinodis, Bothriochloa laguroides, Paspalum notatum, and Paspalum urvillei are native to Brazil; (2) 51% of the reviewed studies prepared extracts from the leaves and used lettuce as the target plant; and (3) 64% of the papers identified allelochemicals, of which 67% were phenolic acids. This first bibliographical survey on allelopathy in Poaceae species present in Brazil shows that less than 3% of the Brazilian species have been studied, suggesting it is an incipient research subject. Since this plant family is a valuable source of unknown natural products, refining such studies should contribute to a better understanding of the ecosystem relationships. Identification and isolation of grass allelochemicals should promote environmentally safer compounds with bioherbicide properties, in sustainable agriculture.

Selective manipulation of a non-dominant plant and its herbivores affects an old-field plant community

Competition and herbivory can interact to influence the recovery of plant communities from disturbance. Previous attention has focused on the roles of dominant plant species in structuring plant communities, leaving the roles of subordinate species often overlooked. In this study, we examined how manipulating the density of a subordinate plant species, Solanum carolinense, and its insect herbivores influenced an old-field plant community in northern Florida following a disturbance. Five years following the disturbance, the initial densities of S. carolinense planted at the start of the experiment negatively influenced total plant cover and species diversity, and the cover of some grasses (e.g., Paspalum urvillei) and forbs (e.g., Rubus trivalis). Selectively removing herbivores from S. carolinense increased S. carolinense abundance (both stem densities and cover), increased the total cover of plants in the surrounding plant community, and affected plant community composition. Some plant species increased (e.g., Digitaria ciliaris, Solidago altissima) and others decreased (e.g., Paspalum notatum, Cynodon dactylon) in cover in response to herbivore removal. Herbivore effects on plant community metrics did not depend on S. carolinense density (no significant herbivory by density interaction), suggesting that even at low densities, a reduction of S. carolinense herbivores can influence the rest of the plant community. The recovery of the plant community was context dependent, depending on site- and plot-level differences in underlying environmental conditions and pre-disturbance plant community composition. We demonstrate that the density of and herbivory on a single subordinate plant species can affect the structure of an entire plant community.

Modelling seed retention curves for eight weed species on clothing

AbstractHumans can unintentionally disperse plant propagules (herein referred to as seeds) including weed seeds from clothing when hiking. There is limited experimental or observational information, however, about unintended human‐mediated seed dispersal, particularly from different types of clothing. We experimentally assessed the probability of seed detaching from socks and trousers along a 5 km standardized route for eight common environmental weeds: Bidens pilosa L., Chloris gayana Kunth., Conyza canadensis L., Cynodon dactylon L., Drymaria cordata (L.) Willd. ex Schult., Poa annua L., Paspalum urvillei Steud. and Sporobolus elongatus R.Br. Seed detachment varied among species on both types of clothing, but seeds more easily detached from trousers than socks. When different models were fitted to the data, a three‐parameter generalized exponential model with curves provided the best fit. The curves were leptokurtic, with peak close to the seed source and a long flat tail, which indicates that most seeds dispersed from clothing fall close (within 5 m) to the point of attachment with only a small proportion of seeds dispersed over long distances. Combining attachment and detachment data for the same species, we estimated the actual numbers of seeds potentially dispersed over a hike of 5 km. The study indicates that most seeds are likely to be dispersed at the start of walks, although the actual number of seeds will vary depending on several factors such as the behaviour of the hiker and the amount of weed seeds present at the start of the walk. Those few seeds dispersed much further may, however, be more important in terms of plant invasions. Covering socks with gaiters and avoiding walking through weedy areas such as road edges and car parks before starting walks could minimize the risk of seeds attaching to clothing and hence being dispersed.

Associations between host plant concentrations of selected biochemical nutrients and Mexican rice borer, Eoreuma loftini, infestation

AbstractThe Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an economic pest of sugarcane (Saccharum spp. hybrids) and other graminaceous host crops, and it attacks grassy weeds. Oviposition preference has been known to be for plants with leaves that form folds. This study is the first to associate the nutritional quality of crop and forage plant hosts with Mexican rice borer injury. Three experiments were conducted to determine the levels of selected biochemical nutrients, including free amino acids and sugars, in four grass weeds [barnyardgrass, Echinochloa crus‐galli (L.); broadleaf signalgrass, Urochloa platyphylla (Munro ex C. Wright); johnsongrass, Sorghum halepense (L.) Pers.; and Vasey's grass, Paspalum urvillei Steud.], a forage grass [sudangrass, Sorghum bicolor (L.) Moensch spp. drummondi (Nees ex Steud.) de Wet & Harlan], three crop species [maize, Zea mays L.; sorghum, Sorghum bicolor (L.) Moench; and sugarcane, Saccharum spp.], and a sorghum‐sudangrass forage hybrid (all Poaceae). Of 16 free amino acids detected among plants in the first two experiments, only high accumulations of free histidine in sudangrass and maize were associated with increased infestations by Mexican rice borer larvae. In all three experiments, high levels of fructose were associated with heightened Mexican rice borer infestation. Ramifications of these findings on the potential dispersal of this invasive pest in the USA and possible applications of fructose in baits are discussed.

Leaf morphoanatomy of species tolerant to excess iron and evaluation of their phytoextraction potential

Setaria parviflora (Poir.) Kerguélen and Paspalum urvillei Steudel are grasses that grow naturally in a soil with high iron contents. This study aimed to characterize morphoanatomically and histochemically the iron phytotoxicity on leaves and evaluate the phytoextraction potential of these grasses. Saplings were cultivated in hydroponic solution with and without excess Fe-EDTA. Regarding measurements taken on leaves, reduction was observed among treatments of Fe-EDTA on height values of abaxial epidermis and bundle sheath in both species. As for iron histolocalization, stronger reaction was observed in leaves of S. parviflora, in comparison with P. urvillei. Anatomical damage, such as protoplast retraction, irregular xylem, changes in cell volume, and cell collapse, and visual symptoms, like leaf bronzing, chlorosis, and necrosis, were similar in both species when exposed to excess iron; however, P. urvillei showed more severe damage. This species accumulated more iron in shoots than S. parviflora and therefore is more favorable for use in phytoextraction. The root system of both species accumulated higher iron concentrations in relation to shoots.

Oviposition and larval development of a stem borer, Eoreuma loftini, on rice and non‐crop grass hosts

AbstractA greenhouse study compared oviposition preference and larval development duration of a stem borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), on rice, Oryza sativa L. cv Cocodrie (Poaceae), and four primary non‐crop hosts of Texas Gulf Coast rice agroecosystems. Rice and two perennials, johnsongrass, Sorghum halepense (L.) Pers., and vaseygrass, Paspalum urvillei Steud. (both Poaceae), were assessed at three phenological stages. Two spring annuals, brome, Bromus spec., and ryegrass, Lolium spec. (both Poaceae), were assessed at two phenological stages. Phenological stages represented the diversity of plant development stages E. loftini may encounter. Plant fresh biomass, dry biomass, and sum of tiller heights were used as measures of plant availability. Accounting for plant availability, rice was preferred over non‐crop hosts, and intermediate and older plants were preferred over young plants. Johnsongrass and vaseygrass were 32–60% as preferred as rice when considering the most preferred phenological stages of each host. Brome and ryegrass received few or no eggs, respectively. Eoreuma loftini larval development (in degree days above developmental threshold temperatures) was fastest on rice and slowest on johnsongrass and vaseygrass. Development duration was only retarded by plant stage on young rice plants. Foliar and stem free amino acid concentrations were determined to help provide insights on the mechanisms of E. loftini oviposition preference and developmental performance.

Feasibility of Using an Alternative Larval Host and Host Plants to Establish <I>Cotesia flavipes</I> (Hymenoptera: Braconidae) in the Temperate Louisiana Sugarcane Ecosystem

Attempts to establish Cotesia flavipes Cameron (Hymenoptera: Braconidae) in Louisiana sugarcane fields to control the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae) have been unsuccessful. Experiments were conducted to investigate the feasibility of using an alternative larval host and host plants to overcome barriers preventing establishment. In addition, we evaluated C. flavipes' ability to search for D. saccharalis in sugarcane without above-ground internodes. Diatraea evanescens Dyar (Lepidoptera: Crambidae) was investigated as an alternative host for C. flavipes. Cotesia flavipes was reared for five generations on D. evanescens without any indication of diminishing fitness as measured by days to parasite pupation and average cocoon mass weight. However, there was a significant reduction in percent parasitism, cocoon mass weight, and percent emergence when C. flavipes parasitized D. evanescens as compared with D. saccharalis, resulting in a 75% reduction in the gross reproductive rate (R(0)). Greenhouse studies indicated little difference in parasitism of D. saccharalis on the weed hosts johnsongrass, Sorghum halepense (L.), and vaseygrass, Paspalum urvillei Steud. However, when planted as refuge plots, we found it difficult to establish infestations of D. saccharalis in either of these hosts, or in two energy sugarcanes. After 3 yr of infesting host plants and releasing parasitoids only one parasitized D. saccharalis larvae was recovered within the johnsongrass refuge. Diatraea evanescens readily established in vaseygrass; however, these larvae appear inaccessible to C. flavipes. In contrast, parasitism of D. saccharalis by C. flavipes infesting young sugarcane was 30%.

Seasonal Infestations of Two Stem Borers (Lepidoptera: Crambidae) in Noncrop Grasses of Gulf Coast Rice Agroecosystems

Infestations of two stem borers, Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) (Lepidoptera: Crambidae), were compared in noncrop grasses adjacent to rice (Oryza sativa L.) fields. Three farms in the Texas rice Gulf Coast production area were surveyed every 6-8 wk between 2007 and 2009 using quadrat sampling along transects. Although D. saccharalis densities were relatively low, E. loftini average densities ranged from 0.3 to 5.7 immatures per m(2) throughout the 2-yr period. Early annual grasses including ryegrass, Lolium spp., and brome, Bromus spp., were infested during the spring, whereas the perennial johnsongrass, Sorghum halepense (L.) Pers., and Vasey's grass, Paspalum urvillei Steud., were infested throughout the year. Johnsongrass was the most prevalent host (41-78% relative abundance), but Vasey's grass (13-40% relative abundance) harbored as much as 62% of the recovered E. loftini immatures (during the winter). Young rice in newly planted fields did not host stem borers before June. April sampling in fallow rice fields showed that any available live grass material, volunteer rice or weed, can serve as a host during the spring. Our study suggests that noncrop grasses are year-round sources of E. loftini in Texas rice agroecosystems and may increase pest populations.

Heavy Metal Accumulation in Plant Species Indigenous to a Contaminated Portuguese Site: Prospects for Phytoremediation

Phytoremediation is a promising alternative to conventional soil clean-up methods; however, up to date, there is still not enough information on plant species suitable for application in this field of science. Therefore, plant screening on contaminated sites can lead to the identification of further species of interest. In the present study, pedological and botanical characteristics of an industrialised area known for its metal contamination, in special with Zn—Esteiro de Estarreja, in Portugal—were examined in a 1-year screening. Twenty-seven species were found, with a higher occurrence and variability in the summer/spring season. Zinc levels in the tissues of the collected plant samples ranged from 34 mg kg−1 in shoots to 2,440 mg kg−1 in roots of different species. Species as Verbascum virgatum, Hypochoeris radicata, Phalaris arundinacea, Conyza bilbaoana, Paspalum urvillei and Aster squamatus have shown high Zn shoot accumulation and bioconcentration factors (BCFshoots > 1) and high metal translocation factors (TF > 1). Others, namely Spergularia capillacea, excluded Zn from the shoot tissues and stored the metal at the root zone (BCFroots > 1), behaving as tolerant plants. Plants were also screened for arbuscular mycorrhizal fungi colonisation, and only few species showed mycorrhizal presence, namely C. bilbaoana, Hirschfeldia incana, Epilobium tetragonum, Conyza sumatrensis, Pteridium aquilinum, P. urvillei and A. squamatus. The present work showed important indigenous species that can cope with installed harsh conditions and with potential for utilisation in phytoremediation strategies, either through metal removal to aerial parts or through its immobilisation in the root zone.