In the laboratory studies on allelopathy, phytotoxicity is defined as a negative impact of plant’s extracts or natural compounds derived from plants, on germination and/or growth of the tested ...(acceptor) plant. Glycoalkaloids are the main biologically active compounds of the potato and are involved in potato phytotoxicity (the correlation coefficient of the length of the test plant with the concentration of total glycoalkaloids present in the leaf extracts of forty potato genotypes was r = -0.41). The assessment of phytotoxic abilities of the potato is a two-step procedure which consists of determining glycoalkaloids in potato leaf extracts and analyzing the root and hypocotyl lengths of the test plant growing in potato leaf extracts.
From the first half of the XX century, the maritime Antarctic was a region with high regional warming rates. At the beginning of the XXI century, regional warming strongly slowed down, but during the ...next twenty years the near-surface temperatures and mean annual precipitation at the Antarctic Peninsula will most probably increase. Higher temperatures and precipitation make the conditions in the maritime Antarctic more favourable for plants, including invasive species. Moreover, the increasing number of Antarctic tourists unintentionally transport thousands of seeds to the Antarctic on their clothes and equipment. In such circumstances, it is important to evaluate possible defensive mechanisms of native plant species, including their allelopathic potential. The objective of this study was to evaluate the allelopathic potential and cytostatic activity of Sanionia georgicouncinata. This species is widespread in the maritime Antarctic and is one of the most abundant moss species on the Argentine Islands (Wilhelm Archipelago). Seeds of cucumber Cucumis sativus, radish Raphanus raphanistrum subsp. sativus, wheat Triticum vulgare, and amaranth Amaranthus paniculatus were used as bioassay species. Fresh green biomass of S. georgicouncinata was used to prepare aqueous extracts with 1 : 10, 1 : 50, and 1 : 100 plant to water ratios. The average root length of wheat sprouts and cucumber sprouts in distilled water did not differ significantly from those in plant extracts. The root length of radish sprouts in 1 : 50 plant extract was significantly shorter than in distilled water. Meanwhile, in 1 : 50 and 1 : 100 water extracts, roots of amaranth plants were significantly longer than in water. The number of lateral roots of cucumber sprouts in water and studied aqueous extracts varied from 1 to 6 with medians from 3 to 4. The medians of control (distilled water) and sample groups (aqueous extracts) did not differ significantly, but only 38.1 ± 6.1% of cucumber sprouts developed lateral roots in the 1 : 10 aqueous extract of S. georgicouncinata, and even less – 28.3 ± 7.5% in the 1 : 50 aqueous extract. The results of this study show that the allelopathic potential of S. georgicouncinata is low. However, a significant cytostatic activity of the studied extracts shows that this species may still affect other plants and animals. Further research is needed to evaluate the impact of the studied extracts on root growth and germination of the invasive plants, particularly Poa annua.
Saltcedars are woody plants in the genus
Tamarix
L. (Caryophyllales: Tamaricaceae) and are native to Eurasia and Africa. Several species have become invasive in the Americas, Australia and South ...Africa. In Argentina there are four species of
Tamarix
distributed in arid, semi-arid and coastal areas of most provinces. The taxonomic isolation of
Tamarix
spp. in Argentina, their widespread distribution, negative impact to natural areas and lack of impact from existing natural enemies all indicate that
Tamarix
is an ideal candidate for classical biological control in Argentina. Biological control of
Tamarix
spp. has been rapid and highly successful in the USA after the introduction of four
Diorhabda
spp. (Coleoptera: Chrysomelidae). Biological control of
Tamarix
spp. in Argentina could be implemented easily, rapidly, and at a low cost by utilizing the information developed in the USA.
Despite their great importance for the food industry, flavorings, in general, raise a number of questions regarding their cytotoxicity, mutagenicity and carcinogenicity, since, in the literature, ...there are few studies found evaluating the toxicity on the systemic and cellular level, of these chemical compounds. The root meristems of Allium cepa (onion) are widely used for the assessment of toxicity of chemical compounds of interest. Thus, this study aimed to evaluate, in A. cepa meristematic cells, individually and in combination at the cellular level, the toxicity of synthetic Cheese and Cheddar Cheese food flavorings, identical to the natural, at doses of 1.0 and 2.0 mL, at exposure times of 24 and 48 hours. In combination we used 0.5 mL of Cheese flavor associated with 0.5 mL of Cheddar flavor; and 1.0 mL of Cheese flavor associated with 1.0 mL of Cheddar flavor, at exposure times of 24 and 48 hours. For these evaluations, we used groups of five onion bulbs, which were first embedded in distilled water and then transferred to their respective doses. The root tips were collected and fixed in acetic acid (3:1) for 24 hours. The slides were prepared by crushing and were stained with 2% acetic orcein. Cells were analyzed throughout the cell cycle, totaling 5,000 for each control and exposure time. The mitotic indices calculated and cellular aberrations observed were subjected to statistical analysis using the chi-square test (p <0.05). No chromosomal abnormalities nor those of mitotic spindle were observed for the treatments performed. The results, both individually and in combination, showed that the flavorings under study significantly reduced the cell division rate of the test system cells used. Therefore, under the conditions studied, the two flavorings were cytotoxic.
In its modern era, the discipline of biological control can be perceived as being subject to a series of tensions due to differences in philosophy, different needs, and different practices; these ...include the view that biological control is environmentally friendly and desirable vs. the view that any organism alien to a particular habitat should be considered an undesirable invasive, the need to protect nontarget species vs. the need to introduce the most effective biological control agents and the need to know what an agent might attack under normal field conditions vs. the restrictive nature of current testing procedures. These tensions are particularly manifest in the area of host-specificity testing where researchers interact most directly with regulators and policy-makers and recent “incidents” of nontarget use by biological control agents in three regions have brought them to the fore. The empirical tension between needing more certainty about agent host-range in the real world and being obliged to test this primarily under highly restricted conditions is of most concern to researchers. This paper suggests ways to reduce this through improvements in (1) what plants are tested, (2) how the selected plants are tested, and (3) how the test data are interpreted and communicated to regulators. It is argued that the currently used centrifugal phylogenetic method for selecting test plant lists should be modernized to accommodate the many recent improvements in knowledge of plant phylogenetic relationships and insect host-choice evolution and behavior. The reliance on quarantine-based testing is briefly examined and low- and high-technology alternatives considered. Both these are rejected, at least in the short-term, as being impractical, and the use is proposed of comparative laboratory-based vs. open-field host tests against a few key nontarget species to proactively calibrate subsequent quarantine data and aid interpretation of results obtained under artificial conditions. While these improvements should help better translate host-test results to real-world outcomes, it is essential that there be increased transparency in the communication of these results to regulators, with discussions of different components of risk, such as localized vs. widespread and short-term collateral damage vs. long-term evolutionary impact. Harmonizing the tensions that currently impinge on biological control can only be achieved through improving the quality of information provided, which will help regulators make decisions that are based more on knowledge and less on the often ill-perceived fears of the public.
Herbicidas que apresentam atividade residual no solo podem se tornar problema para os cultivos agrícolas, pela possibilidade de intoxicar culturas sucessoras. No caso dos hormonais, há grande ...dificuldade na determinação de resíduos pela técnica do bioensaio, em função da variação na resposta em crescimento, apresentada pela espécie indicadora. Neste trabalho, objetivou-se determinar espécies e variáveis sensíveis aos herbicidas 2,4 D e picloram, para indicação de resíduos no solo. Para isso, realizaram-se dois bioensaios, sendo que cada um, constituiu-se de 60 tratamentos, em esquema fatorial, compostos pela combinação de três espécies vegetais (Lycopersicon esculentum, Cucumis sativus e Beta vulgaris), dois substratos (areia e amostra de solo) e dez subdoses do herbicida (0; 3; 6; 12; 22,5; 47; 94; 187,5; 375 e 750 g ha-1) e (0; 3; 6; 9; 18; 30; 60; 123; 246 e 501 g ha-1) para o 2,4-D e picloram, respectivamente. O delineamento experimental utilizado para ambos os ensaios foi em blocos casualizados, com quatro repetições. O aumento das doses dos herbicidas provocou reduções nas variáveis altura de planta, matéria seca e, aumento da intoxicação visual das espécies avaliadas. A intoxicação visual mostrou-se a variável mais adequada para determinação de baixos níveis de resíduos de 2,4 D e picloram no solo. B. vulgaris foi a espécie com maior sensibilidade ao 2,4 D enquanto que L. esculentum foi a espécie mais sensível ao picloram.
Purpose: to assess the fertilizing value of sewage sludge. Materials and methods. The material used for research was sewage sludge from municipal wastewater treatment plants in Novocherkassk with a ...three-year stay period on the sludge map. The research was carried out as a part of a vegetation experiment on soils selected from agricultural lands in Aksai district Rostov region. According to the analysis, the soils are non-degraded, non-saline with a low humus content and an average nutrient content. The granulometric composition of soils is dominated by coarse silt fractions. Sewage sludge, on the contrary, is characterized by a high content of organic matter and nutrients; sand fractions predominate in the granulometric composition. Radish and watercress were used as test plants as they were the most sensitive to the presence of contaminants. Soil bioproductivity was assessed by seed germination, total biomass, and average biomass per plant. Results and discussions. The best germination of plant seeds was noted in variants with the application of sewage sludge to soils in comparison with both the control and the variant of using fertilizers in similar doses of the active substance. Under the influence of sewage sludge, changes in the qualitative composition of soils were noted: the amount of nitrates, phosphates, calcium ions and sulfates increased, and the content of organic matter increased. Conclusions. The positive effect of sewage sludge on plants has been determined: the radish yield increased by 55 % with the use of sewage sludge, and by only 10 % with the use of azofoska (nitrogen-phosphorus potassium fertilizer); the watercress yield increased by 29 % against the background of the use of sewage sludge and by 2 % against the background of the use of azofoska. In variants with the application of sewage sludge, an increase in the content of organic matter by an average of 30 % is observed. In soil samples with sewage sludge, an increase in the nitrogen content by 30–59 %, phosphorus by 67–78 % compared to the control was noted, and when azofoska was added, in comparison with control samples, the amount of nitrogen increased by 5–23 %, and phosphorus by on average by 50 %.
In order to evaluate performance of a bogie more accurately in its planning stage, a rapid prototype bogie has been developed on which performance tests can be conducted on a rolling stock test plant ...without having to manufacture vital test components. The tests were executed by installing several actuators which were controlled to emulate the desired test dampers or rubber bushes. This paper describes the rapid prototype bogie and the results from actuator control tests on damper test equipment and from emulated running tests on the rolling stock test plant.
The paper describes an automated measuring system of a plant, which is designed for the investigation of the mechanical properties of structural materials in a temperature range of 4.2–300 K under ...the action of current pulses.
Over the past 30 years, protocols for the selection of test plants used to determine the host range of candidate biological control agents have remained largely unchanged. Using the case of the ...root-feeding flea beetle,
Longitarsus sp., a candidate agent for biological control of
Heliotropium amplexicaule in Australia, this paper describes a “modernized” protocol, based more strongly on phylogeny, and refined by ecological and biogeographic similarities. Taxonomic nomenclature is de-emphasized in favour of strict phylogenetic relationships and the use of so-called “safeguard species” is abandoned. This is the first time that a biological control agent has been tested for host-specificity and application made for release, based solely on the new protocol, and the changes were acceptable to the regulatory organisations in Australia. The testing showed that adult feeding extended to plant species with up to five degrees of phylogenetic separation from
H. amplexicaule, indicating that there would be a moderate risk that more distantly related plants suffer some feeding damage by adult
Longitarsus sp. when they co-occur with infestations of the target weed that have large flea-beetle populations. Such damage would not have severe consequences for survival and reproduction of the plants. However,
Longitarsus sp. was able to complete its life-cycle on plants related to the target weed by two degrees of phylogenetic separation or less, leaving indigenous
Heliotropium and
Tournefortia species at some risk of colonisation. While these species had different life-histories and/or only slightly overlapped with the actual and potential range of the target weed, a minority of reviewers were concerned that insufficient information was available on the dispersal abilities of
Longitarsus sp. to dismiss this risk. Release was therefore not approved. While disappointing for the biological control project, the outcome was not unexpected, as the assessment was based on factors that modified the effects of host range alone. The new protocols highlighted some problems in the review process concerning an overreliance on taxonomic nomenclature as opposed to actual genetic relationships and an inadequate understanding of the nature of risk. However, they also directed attention to knowledge gaps in biogeography and agent biology that might refine the assessed risk. As such, this process can be considered an improvement in methodology. Moreover, rejection of the application to release
Longitarsus sp. demonstrated that fears expressed by some researchers/regulators that the removal of “safeguard” species would somehow weaken the data and allow unsafe agents to be released were unwarranted.
PDF
