Quiescence, growth and senescence of Egeria densa in Lake Marion

Seasonal changes in biomass production and morphology of the submersed vascular plant Egeria densa Planchon (Brazilian elodea) were followed in Lake Marion, South Carolina, from march 1980 to May 1981. Biomass maxima occurred in late summer and late fall; these were followed by periods of senescence denoted by biomass loss through sloughing and decay of tips and branches. A period of quiescence was observed in the winter. Rootcrowns and stems containing double nodes were verified as the overwintering and propagative structures.     

Seed germination traits of Trapella sinensis (Trapellaceae), an endangered aquatic plant in Japan: Conservation implications

We investigated the effects of cold stratification, temperature, light, and oxygen conditions on seed germination of Trapella sinensis Oliver, an endangered aquatic plant in Japan. Seeds had physiological dormancy, and final germination rate increased with an increasing period of cold stratification. Seeds of T. sinensis had an almost absolute requirement for aerobic conditions to germinate. Also, alternating temperatures significantly promoted germination regardless of light conditions, although final germination percentage was twice to four times higher in light under constant temperature conditions. Suitable sites for germination of T. sinensis appear to be shallow water with alternating temperatures and sufficient oxygen and sediment anoxia, caused by eutrophication of water bodies, may have prevented recruitment of T. sinensis from seed.     

The life cycle of Anguina agrostis: Development in host plant

Bird A.F. and Stynes B.A. 1981. The life cycle of Anguina agrostis: Development in the host plant. Internationaljournal for Parasitology11: 431–440. The growth and development of the infective second stage “dauer” larvae (DL₂) of Anguina agrostis into adults have been followed under field conditions in rye grass (Lolium rigidum). Three moults were observed to occur during the parasitic phase of development. From the third (second parasitic) moult onwards, there was much more variability in the size of the female nematodes than in the males and sexual dimorphism became very pronounced. The transition from the DL₂ to the second stage parasitic larva (PL₂) is marked by the disappearance of the numerous lipid storage granules which are characteristic of the DL₂, and the development in the PL₂ of an intestine which becomes more pronounced in each succeeding stage, particularly in the adult female. Anguina agrostis is unusual among parasitic nematodes in that the DL₂ has the thickest cuticle of all stages, including adults. The L₄ and adult males have thicker cuticles than the females at the same stages of development. Moulting appears to involve resorption of the innermost basal zone of the shed cuticle as well as morphological and chemical changes to the epicuticle.     

Phytoaccumulation of zinc by the aquatic plant, Lemna gibba L.

The uptake of zinc (Zn) by the duckweed Lemna gibba L., native to the north-east region of Algeria, was investigated in quarter Coïc solutions enriched with 6.0, 10.0, 14.0 and 18.0 mg l⁻¹ of Zn supplied as zinc sulphate (ZnSO₄). Zinc concentrations were measured in the water daily and in duckweed biomass at the end of the experiments. These results showed that under experimental conditions (pH = 6.0 ± 0.1, T = 21 ± 1 °C, photoperiod = 12 h/j), L. gibba was able to accumulate in its biomass 4.23; 15.62; 23.88 and 25.81 mg g⁻¹ DM, respectively for the four initial concentrations selected. At these concentrations, the metal removed percentages were 61–71%. The mass balance performed on the system showed that about 49–68% of Zn (depending on the initial concentration in water) was removed by precipitation as zinc phosphate. The results showed that this aquatic plant can be successfully used for Zn removal.     

In vitro regeneration of an endangered medicinal plant Picrorhiza scrophulariiflora

A reproducible in vitro regeneration system for Nepalese kutki (Picrorhiza scrophulariiflora Pennell) was developed from in vitro leaf derived callus. Induction of more than seven shoot buds per explant was achieved on Woody plant medium (WPM) supplemented with 0.53 μM α-napthaleneacetic acid (NAA) and 0.23 μM kinetin (KIN). The shoots were elongated on WPM supplemented with 0.44 μM 6-benzylaminopurine (BAP) and rooted on WPM supplemented with 5.3 μM NAA within 2 weeks. The random amplified polymorphic DNA (RAPD) analysis indicated genetic uniformity of the micropropagated plants with its donor plants.     

Reproductive biology in an invasive plant Solidago canadensis

Solidago canadensis, a perennial Compositae plant originating from North America, was introduced into China as a horticultural plant in 1935. Under natural conditions, S. canadensis allocates large amounts of energy to sexual reproduction and produces many seeds, which reflects an r-strategy with high seed number and small seed size. In addition, naturalized populations have a great capacity to grow clonally with underground stems. S. canadensis has become an invasive weed in eastern China, and has caused serious damages to agricultural production and ecosystems in several provinces in China. In order to understand the reproductive characteristics of S. canadensis and effectively control its spread, we examined soil conditions, seed characteristics, seed germination and the capacity for asexual reproduction in different plant parts. We investigated the population dispersion of S. canadensis in fixed sites for three years, and analyzed the seasonal dynamics of the morphological parameters of the underground parts and the caloric values of different organs of S. canadensis. We also compared differences in the root systems of S. canadensis and composite exotic weeds. The following results were obtained:

Life cycle assessment of a pyrolysis/gasification plant for hazardous paint waste

Goal, Scope and Background Life Cycle Assessment (LCA) remains an important tool in Dutch waste management policies. In 2002 the new National Waste Management Plan 2002–2012 (NWMP) became effective. It was supported by some 150 LCA studies for more than 20 different waste streams. The LCA results provided a benchmark level for new waste management technologies. Although not new, operational techniques using combined pyrolysis/gasification are still fairly rare in Europe. The goal of this study is to determine the environmental performance of the only full scale pyrolysis/gasification plant in the Netherlands and to compare it with more conventional techniques such as incineration. The results of the study support the process of obtaining environmental permits. Methods In this study we used an impact assessment method based on the guidelines described by the Centre of Environmental Science (CML) of Leiden University. The functional unit is defined as treatment of 1 ton of collected hazardous waste (paint packaging waste). Similar to the NWMP, not only normalized scores are presented but also 7 aggegated scores. All interventions from the foreground process (land use, emissions, final waste) are derived directly from the site with the exception of emissions to soil which were calculated. Interventions are accounted to each of the different waste streams by physical relations. Data from background processes are taken from the IVAM LCA database 4.0 mostly originating from the Swiss ETH96 database and adapted to the Dutch situation. Allocation was avoided by using system enlargement. The study has been peer reviewed by an external expert. Results and Discussion It was possible to determine an environmental performance for the pyrolysis/ gasification of paint packaging waste. The Life Cycle Inventory was mainly hampered by the uncertainty occurred with estimated air emissions. Here several assumptions had to be made because several waste inputs and two waste treatment installations profit from one flue gas cleaning treatment thus making it difficult to allocate the emission values from the flue gasses. Compared to incineration in a rotary kiln, pyrolysis/gasification of hazardous waste showed better scores for most of the considered impact categories. Only for the impact categories biodiversity and life support the incineration option proved favorable due to a lower land use. Several impact categories had significant influence on the conclusions: acidification, global warming potential, human toxicity and terrestrial ecotoxicity. The first three are related to a better energy efficiency for pyrolysis/gasification leading to less fossil energy consumption. Terrestrial ecotoxicity in this case is related to specific emissions of mercury and chromium (III). A sensitivity analysis has been performed as well. It was found that the environmental performance of the gasification technique is sensitive to the energy efficiency that can be reached as well as the choice for the avoided fossil energy source. In this study a conservative choice for diesel oil was made whereas a choice for heavy or light fuel oil would further improve the environmental profile. Conclusions Gasification of hazardous waste has a better environmental performance compared to the traditional incineration in rotary kilns mainly due to the high energy efficiency. As was determined by sensitivity analysis the differences in environmental performance are significant. Improvement options for a better performance are a decrease of process emissions (especially mercury) and a further improvement of the energy balance by decreasing the electricity consumption for shredders and oxygen consumption or making more use of green electricity. Recommendations and Perspectives Although the life cycle inventory was sufficiently complete, still some assumptions had to be made in order to establish sound mass balances on the level of individual components and substances. The data on input of waste and output of emissions and final waste were not compatible. It was recommended that companies put more emphasis on data storage accounted to particular waste streams. This is even more relevant since more companies in the future are expected to include life cycle impacts in their environmental performance.     

Life cycle and matrix analyses for re-refined Oil in Japan

Unstable market systems and consumer preferences for virgin oil have inhibited the development of waste oil re-refining in Japan. In this papery comparative life cycle inventories were developed for re-refining waste oil and for the no-refining case in which the waste oil is incinerated and needs are supplied with virgin oil. Total energy, CO₂, NO_x, and SO₂ emissions were included during the re-refining and consumption (incineration) stages; all are lower in the case of re-refined fuel use. In addition, by using a streamlined LCA matrix, we demonstrate that re-refining waste oil can reduce environmental impacts compared with the case in which virgin oil is chosen.     

Jasmonic acid as modulator of lead toxicity in aquatic plant Wolffia arrhiza (Lemnaceae)

The present study was undertaken to test the influence of exogenously applied jasmonic acid (JA) upon the growth and metabolism of Wolffia arrhiza (Lemnaceae), the smallest vessel aquatic plant exposed to lead (Pb) stress. It was found, that JA acted in a concentration-dependent manner. Treatment with JA at the highest concentration 100 μM resulted in the enhancement of heavy metal toxicity leading to increase in metal biosorption and formation of lipid peroxides as well as decrease in fresh weight, chlorophyll a, carotenoid, monosaccharide and soluble protein content. In contrast, this phytohormone applied at 0.1 μM protected W. arrhiza fronds against Pb stress inhibiting heavy metal accumulation, restoring plant growth and primary metabolite level. Moreover, JA at 0.1 μM activated enzymatic (catalase, ascorbate peroxidase, NADH peroxidase) and non-enzymatic antioxidant (ascorbate, glutathione) system in W. arrhiza, and therefore, suppressed oxidative destruction of cellular components induced by heavy metal. The data suggest that JA plays an important role in the growth and metabolism of W. arrhiza exposed to abiotic stressor and its high adaptation ability to metal contamination of aquatic environment.     

The effect of flow turbulence on plant growth and several growth regulators in Egeria densa Planchon

The effects of turbulence velocity on Egeria densa Planchon was studied for 12 weeks using mechanically oscillating grid-generated turbulence without mean flow. The root-mean-square of the turbulence velocity fluctuations (u′) ranged from 1.62 ± 0.44 to 2.86 ± 0.8 cm s⁻¹ (high turbulence), 1.36 ± 0.2 to 1.86 ± 0.78 cm s⁻¹ (medium turbulence) and 0.67 ± 0.12 to 0.81 ± 0.16 cm s⁻¹ (low turbulence). The control was subjected to gentle manual mixing once a day. Shoot elongation was significantly reduced with increasing turbulence intensity, and the endogenous indole acetic acid (IAA) concentration was significantly decreased with increasing turbulence intensity and exposure time. The plants exposed to high turbulence showed a 64.6% decrease in endogenous IAA concentration compared to the control, while it was decreased only 26.9% in plants exposed to low turbulence. IAA and cytokinin catabolism was increased, and there was an increase in the hydrogen peroxide concentration of the tissues, which triggered peroxidase activity. The total chlorophyll and chlorophyll a content decreased with the time of exposure. Although the flow turbulence negatively affected plant growth and metabolism, all of the plants survived for the experimental period.     

Life cycle of the aquatic firefly Luciola ficta (Coleoptera: Lampyridae)

This research is the first to record the complete life history of the aquatic firefly Luciola ficta (Olivier) using a unique individual rearing method. Transparent containers (250 ml; height: 6 cm; bottom diameter: 8 cm; mouth diameter: 9.5 cm) were used to rear individuals from egg to adult in the laboratory, so that they could be observed throughout the whole life cycle. Larvae were fed on the meat of the water snail Cipangopaludina chinensis (Gray). Temperature ranged from 18 °C to 30 °C, relative humidity (RH) was 80 ± 5%, and the light:dark (L:D) ratio was 10:14. Of 80 eggs, 35 individuals completed their life cycle under these laboratory conditions in Jiji, Nantou County, Taiwan. The external morphological characteristics of each growing stage were described. Egg hatching rate was 95%. On average, one generation spanned 388.2 ± 25.7 days. The durations of egg, larva, climbing larva, cocoon, and adult stages were 19.1 ± 1.5 days, 328.9 ± 33.2 days, 10.9 ± 7.8 days, 14.7 ± 5.3 days, and 15.7 ± 5.2 days, respectively. The number of larval instars ranged from five to seven, with a modal value of six instars for males and seven instars for females. Female larval duration averaged 337.1 ± 31.2 days, which was higher than the 307.6 ± 34.1 days of the males. From January to December 2002, adult emergence peaked twice, with the main high peak appearing in April and the second peak occurring in August. The results of indoor rearing and of field investigations in Jiji, Nantou County, suggested that L. ficta is univoltine. Adult body length is negatively correlated with larval duration (P < 0.01). The life history traits of L. ficta show plasticity in adult occurrence, egg size, egg duration, larval duration, larval instars, and adult body length. Some variations were discussed in the context of survivorship in field habitats.     

Diaspora, a large family of Ty3 - gypsy retrotransposons in Glycine max, is an envelope-less member of an endogenous plant retrovirus lineage

Background  

The chromosomes of higher plants are littered with retrotransposons that, in many cases, constitute as much as 80% of plant genomes. Long terminal repeat retrotransposons have been especially successful colonizers of the chromosomes of higher plants and examinations of their function, evolution, and dispersal are essential to understanding the evolution of eukaryotic genomes. In soybean, several families of retrotransposons have been identified, including at least two that, by virtue of the presence of an envelope-like gene, may constitute endogenous retroviruses. However, most elements are highly degenerate and are often sequestered in regions of the genome that sequencing projects initially shun. In addition, finding potentially functional copies from genomic DNA is rare. This study provides a mechanism to surmount these issues to generate a consensus sequence that can then be functionally and phylogenetically evaluated.     

In vitro tuberization and plant regeneration from multinodal segment culture of Habenaria bractescens Lindl., an Argentinean wetland orchid

Tuberization in many terrestrial orchids represents the most important physiological process for reproduction and survival. An in vitro controlled and reproducible tuberization and plant regeneration system was designed for Habenaria bractescens. Multinodal segments were incubated on Murashige and Skoog (MS) medium supplemented with different concentrations of N⁶-benzylaminopurine (BAP) and sucrose. After 45 days, the explants developed root tubers in vitro in 8 of the 12 media assayed. MS medium with 87.6 mM sucrose plus 4.4 μM BAP was one of the most effective for stimulating root tubers. Plants derived from in vitro root tubers were successfully transferred to the greenhouse without any acclimatization. The morphology and anatomy of the regenerated underground organs were examined to find identifying and distinguishing features. The protocol to regenerate root tubers of H. bractescens will be useful to study the basic aspects and control of tuberization and to carry out restoration programs.