Leersia Oryzoides Research Articles

Cesium-137 partitioning to wetland sediments and uptake by plants

Studies were undertaken to develop a conceptual model for conducting ecological risk assessment at the R-Canal, located on the Savannah River Site, Aiken, South Carolina. Soil profiles collected from within the canals indicated that the maximum 137 Cs concentrations generally occurred at a depth between 2.5 and 7.5 cm. The original 137 Cs deposits, the result of accidental releases in the early 1960’s, were covered by newly formed organic and/or fluvial deposits. About 60% of the total 137 Cs inventory in each core existed at the organic matter/mineral interface. Based on sequential extraction tests, most of the Cs in this layer was held by either amorphous Fe-oxyhydroxides or organic matter. Sequential extraction tests also indicated that almost half of the Cs was weakly bound to the soil (either exchangeable or associated with amorphous Fe-oxides), a percentage that is five times greater than reported at the Hanford Site. 137 Cs distribution within the profile was controlled more when the 137 Cs was released than by the composition (organic matter concentrations, mineralogy, particle size distribution) of the soil. Netted chain fern had greater plant : soil concentration ratios in drier terrestrial environments than in wetland environments. The cause may be related to the Cs existing in a more bioavailable form or to the better overall health of the plants under drier soil conditions. The average concentration ratio was greater for the netted chain fern 2.78±2.96 than for rice cutgrass 0.18±0.13. The overall average plant : soil concentration ratio, 1.05±2.01, was large and points out, yet again, that Cs bioavailability is greater on the SRS than at most other sites.

Innovative uses of vegetated drainage ditches for reducing agricultural runoff

Vegetated agricultural ditches play an important role in mitigation of pesticides following irrigation and storm runoff events. In a simulated runoff event in the Mississippi (USA) Delta, the mitigation capacity of a drainage ditch using the pyrethroid esfenvalerate (Asana XL) was evaluated. The pesticide was amended to soil prior to the runoff event to simulate actual runoff, ensuring the presence of esfenvalerate in both water and suspended particulate phases. Water, sediment, and plant samples were collected temporally and spatially along the drainage ditch. Even with mixing of the pesticide with soil before application, approximately 99% of measured esfenvalerate was associated with ditch vegetation (Ludwigia peploides, Polygonum amphibium, and Leersia oryzoides) three hours following event initiation. This trend continued for the 112 d study duration. Simple modeling results also suggest that aqueous concentrations of esfenvalerate could be mitigated to 0.1% of the initial exposure concentration within 510 m of a vegetated ditch. Observed field half-lives in water, sediment, and plant were 0.12 d, 9 d, and 1.3 d, respectively. These results validate the role vegetation plays in the mitigation of pesticides, and that ditches are an indispensable component of the agricultural production landscape.

Seedling emergence from seed banks of tidal freshwater wetlands: response to inundation and sedimentation

Seed banks play a critical role in the maintenance of many wetland plant communities, and recruitment from the seed bank in response to environmental heterogeneity may influence species diversity and the spatial pattern seen in vegetation. Reduced recruitment in tidal freshwater wetlands in the Nanticoke River watershed (Maryland and Delaware, USA) may result from sediment input or sea level rise. An experimental test of the effects of inundation and sedimentation was conducted on seedling emergence from a pooled seed bank of tidal freshwater wetlands in a 2×5 factorial greenhouse experiment. Treatments were two levels of inundation (flooded and non-flooded) and five levels of sediment addition (0–2 cm depth). Twenty taxa emerged from the pooled wetland seed bank, with Leersia oryzoides and Typha species occurring the most frequently. A significant decrease was seen in seedling emergence due to flooding ( P=0.003), and the addition of sediment significantly decreased taxa density ( P=0.023) and seedling emergence ( P=0.0069). These findings suggest that the expression of species from the seed bank is largely controlled by sedimentation rates and hydrology, and that increases in sedimentation and relative sea level may reduce plant biodiversity of tidal freshwater wetlands.

Comparative ecophysiology of four wetland plant species along a continuum of invasiveness

We compared the ecophysiological performance of four dominant, perennial plant species of tidal marshes of northeastern North America (Phragmites australis, Typha angustifolia, Spartina alterniflora, and Leersia oryzoides), asking whether species that fall along a continuum of invasiveness vary consistently in terms of primary productivity, growth, biomass allocation, phenology, maximal photosynthetic rate, leaf turnover, tissue nutrient and chlorophyll content, and water use. During 1999, we examined plants growing at two brackish marshes and two freshwater tidal marshes in southern Connecticut, USA. Phragmites and Typha consistently exceeded the other two species in both marsh types in terms of ramet biomass, standing crop, length of the growing season, standing leaf area, leaf longevity, and total chlorophyll. Typha, Phrag- mites, and Spartina showed similar maximal photosynthetic rates across marsh types, significantly greater than the P max observed in Leersia. Foliar nitrogen was significantly greater in Phragmites than in all other species, suggesting that this species accrues nutrients more efficiently. Phragmites and Typha populations did not differ in a number of characters between freshwater and brackish marshes, indicating low sensitivity to exposure to moderate salinity levels. A principle components analysis placed Phragmites and Typha close to each other and more distant from Spartina and Leersia along axes describing components of competitive ability and photosynthetic performance. Thus, moderately and highly invasive species are distinct from less invasive species in terms of ecophysiology in both wetland types. As Phragmites australis and Typha an- gustifolia displace other plant species in marshes, they will likely influence the carbon- and nitrogen-cycling functions of wetlands, subject to the species' varying tolerances for salinity.

Chiral response of Oryzeae and Paniceae plants in alpha-methylbenzyl-3-p-tolyl urea agar medium.

The results presented here support the hypothesis that plants of the tribe Oryzeae respond enantioselectively and homogeneously to optically active 1-alpha-methylbenzyl-3-p-tolylurea (MBTU) in root growth inhibition, in contrast to Echinochloa species. The Oryzeae plants tested in this study belong to different genera (Oryza, Leersia, Chikusichloa and Zizania), to different species (O sativa, O glaberrima, O alta, O coarctata, O latifolia, O minuta, O rufipogon), to various ecospecies of Oryza (japonica, indica, japonica x indica, javanica) and to different levels of evolution [cultivated rice (O sativa and O glaberrima) and ancestral wild rice species]. In spite of their different phylogenic status and diverse sensitivity, the root growth of all members of the genus Oryza was inhibited more by R-MBTU than by S-MBTU. Zizania palustris, Z latifolia, Leersia oryzoides and Chikusichloa aquatica belonging to the tribe Oryzeae exhibited similar chiral recognition to the Oryza plants, suggesting that Oryzeae have a common chiral recognition mechanism in their response to optically active MBTUs. In contrast, Echinochloa plants (E crus-galli (L) Beauv var crus-galli and E colonum (L) Link), belonging into subfamily Panicoideae tribe Paniceae, responded in a different way, where their root growth was more sensitive to S-MBTU than to the antipodal R-MBTU. A reverse chiral response between the tribe Oryzeae and the genus Echinochloa was clearly indicated in this study. This diverse response may be relevant to Gramineae classification.

Pathogenicity, Mating Ability and DNA Restriction Fragment Length Polymorphisms of Pyricularia Populations Isolated from Gramineae, Bambusideae and Zingiberaceae Plants

Eighty-five Pyricularia isolates were collected from 29 host species of Gramineae, Bambusideae and Zingiberaceae plants sampled in Brazil, Uganda, Ivory Coast, India, Nepal, China, Indonesia and Japan. These isolates were compared on the basis of pathogenicity, mating ability and restriction fragment length polymorphisms with single-copy DNA probes. Based on the pathogenicity to eight differential gramineous plants, these isolates were classified into seven pathotypes: finger millet type, foxtail millet type, common millet type, rice type, crabgrass type, Italian ryegrass/ weeping lovegrass type, and non-cereal/grass type. Genetic variation among these isolates was assessed by RFLP analysis with two restriction enzymes and nine single-copy DNA probes isolated from a finger millet strain. An UPGMA dendrogram based on the RFLPs revealed that the 85 isolates could be classified into seven major groups. Isolates from cereal crops (finger millet, foxtail millet, common millet, wheat and rice) and a grass, Brachiaria plantaginea, were clustered into a single group. They were further divided into six subgroups corresponding to the pathotypes. Among cereal crop isolates only an isolate from pearl millet was located into a different group. The remaining isolates were clustered into five groups designated as the crabgrass group, the buffelgrass and jungle rice group, the rice cutgrass, knotroot bristlegrass and Setaria tomentosa group, the bamboo and bamboo grass group and the Zingiber mioga group. The isolates from cereal crops were generally capable of mating with finger millet strains and constituted a closed mating compatibility group. These results suggested that the isolates from cereal crops form a single group with a common ancestor although they are pathogenic to taxonomically diverse plants. A combined analysis of the pathogenicity and genetic similarity suggested that the transmission of M. grisea isolates occurs in natural agroecosystems between finger millet and Eleusine africana, goosegrass or Bambusa arundinacea, between foxtail millet and green bristlegrass, and between rice and tall fescue, Italian ryegrass, sweet vernalgrass, reed canarygrass or Oryza longistaminata.

Reserves of buried seeds in beaver ponds

Reserves of buried seeds are known to have an important role in the dynamics of plant communities. This is particularly so in wetlands, where periodic low water events are essential for plants to re-establish from seeds. In spite of the growing literature on reserves of buried seeds, little is known about this resource in beaver ponds. This study was designed to 1) document species found in beaver pond seed banks, 2) estimate their relative abundance, and 3) test whether the abundance and richness of seeds differ between young and old beaver ponds. Soil samples were collected from 14 beaver ponds in Gatineau Park (Quebec) in May 1995. Samples were spread out in plastic trays containing a sand and peat substrate and were placed in a growth chamber with fluctuating light and temperature regimes to stimulate germination. More than 2000 seedlings representing 42 species germinated from the various soil samples, yielding an estimated density of 2300 seedlings/m2.Juncus effusus (426 seeds/m2),Leersia oryzoides (390 seeds/m2),Scirpus cyperinus (246 seeds/m2),Juncus brevicaudatus (170 seeds/m2), andLudwiga palustris (98 seeds/m2) were the 5 most abundant species. The abundance and richness of germinating seeds did not differ significantly between young and old beaver ponds.

Recovery of freshwater marsh vegetation after a saltwater intrusion event.

Greenhouse mesocosms of freshwater marsh vegetation were exposed to a simulated saltwater intrusion event followed by a recovery period during which water levels and interstitial water salinity were adjusted over a range of conditions. Virtually all above-ground vegetation, including the three dominant species, Sagittaria lancifolia L., Leersia oryzoides (L.) Swartz, and Panicum hemitomon Schultes, was killed by the initial saltwater intrusion event. P. hemitomon did not recover, but S. lancifolia and L. oryzoides, as well as many of the other species initially present, exhibited some ability to recover depending on post-saltwater intrusion conditions. Increasingly harsh recovery conditions (for freshwater marsh vegetation), including more reduced soil conditions, higher interstitial salinities, and higher interstitial sulfide concentrations were associated with decreased live above-ground biomass and species richness. The effect of elevated salinity on vegetative recovery became more pronounced under flooded conditions. This experiment illustrates that the response of a freshwater marsh community to the long-term disturbance effect of a transient saltwater intrusion event will be strongly influenced by post-intrusion salinity and water levels.

Effects of prescribed fire on moist-soil vegetation and soil macronutrients

Plant succession and various environmental conditions can decrease productivity of wetlands managed intensively for wildlife. Although prescribed fire frequently is used to alter plant composition and structure in semipermanent wetlands, the impacts of fire on species composition and production of seed in moist-soil impoundments have not been quantified. Therefore, I compared species composition, seed production, and soil macronutrient concentrations at the end of the growing season on unburned control sites (n=3) and sites burned in spring (n=3) and summer (n=3) in southeast Missouri. Sites burned in spring contained a greater (P≤0.05) percent cover of beggarticks (Bidens spp. [31.4±4.7%]) and ricecut grass (Leersia oryzoides [50.3±7.0%]) than control and summer-burned sites. The percent cover of marsh elder (Iva ciliata) was reduced (P 0.05) among control sites and sites burned in spring and summer. In general, burning in spring improved habitat and food conditions for waterfowl, whereas burning in summer reduced the prevalence of both desirable and undesirable vegetation and created habitat conditions that favored shorebirds.

Plant Litter Decomposition in Wetlands Receiving Acid Mine Drainage

AbstractThe impact of acid mine drainage on the decomposition of wetland plant species of northern West Virginia was studied to determine if the potential exists for nutrient cycling to be altered in systems used to treat this drainage. There were two objectives of this study. First, decomposition of aboveground plant material was measured to determine species decomposition patterns as a function of pH. Second, decomposition of litter from various pH environments was compared to assess whether litter origin affects decomposition rates. Species differences were detected throughout the study. Decomposition rates of woolgrass [Scirpus cyperinus (L.) Kunth] and common rush (Juncus effusus L.) were significantly lower than those of calamus (Acorus calamus L.) and rice cutgrass (Leersia oryzoides L.). Differences among species explained a large proportion of the variation in percentage of biomass remaining. Thus, differences in litter quality among species was important in determining the rate of decomposition. In general, significantly more decomposition occurred for all species in high pH environments, indicating impeded decomposition at low pH. While decomposition of some species litter differed depending on its origin, other species showed no effect. Cattail (Typha latifolia L.), in particular, was found to have lower decomposition rates occurring with material grown at low pH. Lower decomposition rates could result in lower nutrient availability leading to further reduction of productivity under low pH conditions.

Reforestation of Drained Beaver Impoundments

Abstract Performance of 1-0 bareroot green ash (Fraxinus pennsylvanica Marsh.), sycamore (Platanus occidentalis L), and baldcypress (Taxodium distichum L., Rich.) planted on drained beaver (Castor canadensis) impoundments in southwest Tennessee was promising at the end of three growing season.First-year survival was significantly increased in plots where swamp cut grass (Leersia oryzoides) was controlled; however, effective grass control opened the site to aggressive invasion by broadleaf herbaceous vegetation. No treatment effect was noted for survival or growth of seedlings by the end of the third year. Containerized seedlings of swamp white oak (Quercus michauxii Nutt.) and willow oak (Quercus phellos L) failed due to poorly developed planting stock. Natural regeneration 3 years after drainage was poor, averaging 333 boxelder (Acer negundo L.), 42 black willow(Salix nigra Marsh), and 21 cherrybark oak (Quercus falcata var. pagodaefolia Ell.) stems/ac. Continued beaver control was necessary to prevent recolonization of plantation sites. South. J. Appl. For. 16(3):151-155.

Some effects of acidic growing conditions on three emergent macrophytes: Zizania aquatica, Leersia oryzoides and Peltandra virginica

Transplants of Zizania aquatica L., Leersia oryzoides (L.) Shwartz, and Peltandra virginica (L.) Schott and Endl. were grown for ten weeks in simulated marsh conditions under acidic (pH 3·0, pH 4·0) treatment regimes and compared with controls (pH 5·6). Mortality was low in all treatments and nearly all plants of Z. aquatica and L. oryzoides flowered. Under acidic conditions, transplant height and root biomass of Z. aquatica were significantly reduced, with greater culm numbers and total lenghts of inflorescences per flowering plant compared to controls. Shoot biomass of L. oryzoides transplants was significantly greater in the most acidic treatment (pH 3·0). Transplants of P. virginica grew slowly and did not flower during the experiment; heights and shoot biomass of P. virginica were significantly reduced with increased leaf chlorosis in acidic conditions.

Food Use by Migratory Female Mallards in Northwest Missouri

We studied foods of migratory female mallards (Anas platyrhynchos) relative to habitat and molt during fall 1984 and 1985 in northwest Missouri. Females consumed primarily plant foods in moist-soil, arrowhead (Sagittaria latifolia), and mixed habitats (mixtures of moist-soil and arrowhead plants), but the importance of individual foods varied among habitats. Seeds of wild millet (Echinochloa spp.) and nodding smartweed (Polygonum lapathifolium) accounted for 85% of the mallard diet in moist-soil habitat, whereas seeds and tubers of arrowhead comprised >40% of the diet in arrowhead habitats. These foods and rice-cutgrass (Leersia oryzoides) seeds were important in mixed habitats. Invertebrates comprised 1.6, 6.3, and 17.1% of the diet by mass for females from moist-soil, mixed and arrowhead habitats, respectively. Invertebrate consumption was not correlated with intensity of molt and did not vary with molt completion. Diets of female mallards collected at roosts during fall and spring consisted of primarily agricultural foods

Response of a freshwater marsh plant community to increased salinity and increased water level

Field and greenhouse experiments in which salinity and elevation were manipulated demonstrated that the response of freshwater marshes to saltwater intrusion may be variable and dependent upon a number of factors including: species composition; level, duration, and abruptness of exposure to saline water; flooding depth; a source of propagules of more salt-tolerant species. In the field, saltwater intrusion was simulated by transplanting swards of a freshwater marsh to a higher salinity area. The three dominant species, Panicum hemitomon Schultes, Leersia oryzoides (L.) Swartz, and Sagittaria lancifolia L., succumbed to the sudden increase in salinity to 15%. However, the denuded plots were rapidly invaded by more salt-tolerant species that were present in the higher salinity marsh. Although growth was reduced, Panicum hemitomon and Leersia oryzoides were relatively tolerant of salinities up to 9.4% for at least 1 month in the greenhouse. Sagittaria lancifolia was less tolerant of salinity increases and showed symptoms of tissue damage at 4.8%. A decrease in elevation, which resulted in an increase in mean water level and a more reduced soil environment, caused a significant decrease in live above-ground biomass and stem density in the experimental field plots.

Extraction, Fecundity, and Hosts of Criconemella Rustica

The centrifugal flotation method, using a 200-mesh (75 μm opening) or finer sieve, a sugar flotation medium (sp. gr. 1.18) and a horizontal rotor, produced maximum extraction of ring nematode, Criconemella rustica (Micoletzky), from soil. Females of C. rustica deposited up to 18 eggs, and hatch occurred in 14-21 days. Rice cutgrass, orchard-grass and bottle-brush grass were the best of 39 hosts of M. rustica.

Asiatic Clam (Corbicula manilensis) and Other Foods Used by Waterfowl in the James River, Virginia

Corbicula manilensis was found in the gizzards of 24 ducks of 5 species taken from the James River, Virginia, between 1973 and 1976. Percent average volume in these species ranged from trace to 6%. This is the first known occurrence of this exotic clam in the food of duck in Chesapeake Bay. A total of 135 other food items was identified from the 116 gizzards of 9 species that were examined. Food that predominated includedCyperus spp.,Leersia oryzoides, Polygonum spp., andZea mays. The great diversity of food consumed in this fresh tidal section of the James River indicates the high value of these wetlands to waterfowl. *** DIRECT SUPPORT *** A01BY015 00008

Leersia oryzoides, a Natural Host and Winter Reservoir of the Rice "Giallume" Strain of Barley Yellow Dwarf Virus1)

Leersia oryzoides, a Natural Host and Winter Reservoir of the Rice "Giallume" Strain of Barley Yellow Dwarf Virus1)

Observations on the Phloem Ultrastructures of Some Gramineae

SUMMARYIn the phloem plastids of sectioned Hordeum vulgare and Leersia oryzoides, crystalloids with parallel subunits, similar to the ones already observed in Oryza sativa and Zea mays, are described. In L. oryzoides a type of plastid resembling the kind described in Chenopodiaceae and Aizoaceae was also observed.The occurrence of P-protein in sectioned sieve tubes of Holcus lanatus and L. oryzoides, is reported.

サヤヌカグサ除去による常発地でのイネ白葉枯病の防除効果

サヤヌカグサ除去による常発地でのイネ白葉枯病の防除効果

Waterfowl Populations and the Changing Environment of the Illinois River Valley

Waterfowl Populations and the Changing Environment of the Illinois River Valley