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Climate change influences the ecological environment and affects the recruitment of plants, in addition to population dynamics, including Scots pine regeneration processes. Therefore, the impact of cover-dominant species extracts on the germination of pine seeds and morpho-physiological traits of seedling under different environmental conditions was evaluated. Increasing temperature reinforces the plant-donor allelochemical effect, reduces Scots pine seed germination, and inhibits seedling morpho-physiological parameters. Conditions unfavourable for the seed germination rate were observed in response to the effect of aqueous extracts of 2-year-old Vaccinium vitis-ideae and 1-year-old Calluna vulgaris under changing environmental conditions.&nbsp, The lowest radicle length and hypocotyl growth were observed in response to the effect of 1-year-old C. vulgaris and 2-year-old Rumex acetosella under increasing temperature (+4 °C) conditions. The chlorophyll a + b concentration in control seedlings strongly decreased from 0.76 to 0.66 mg g−1 (due to current environmental and&nbsp, changing environmental conditions). These factors may reduce the resistance of Scots pine to the effects of dominant species and affect the migration of Scots pine habitats to more favourable environmental conditions.

The recent decline of Lepidoptera species strongly correlates with the increasing intensification of agriculture in Western and Central Europe. However, the effects of changed host-plant quality through agricultural fertilization on this insect group remain largely unexplored. For this reason, we tested the response of six common butterfly and moth species to host-plant fertilization using fertilizer quantities usually applied in agriculture. The larvae of the study species Coenonympha pamphilus, Lycaena phlaeas, Lycaena tityrus, Pararge aegeria, Rivula sericealis and Timandra comae were distributed according to a split-brood design to three host-plant treatments comprising one control treatment without fertilization and two fertilization treatments with an input of 150 and 300 kg N ha−1 year−1, respectively. In L. tityrus, we used two additional fertilization treatments with an input of 30 and 90 kg N ha−1 year−1, respectively. Fertilization increased the nitrogen concentration of both host-plant species, Rumex acetosella and Poa pratensis, and decreased the survival of larvae in all six Lepidoptera species by at least one-third, without clear differences between sorrel- and grass-feeding species. The declining survival rate in all species contradicts the well-accepted nitrogen-limitation hypothesis, which predicts a positive response in species performance to dietary nitrogen content. In contrast, this study presents the first evidence that current fertilization quantities in agriculture exceed the physiological tolerance of common Lepidoptera species. Our results suggest that (1) the negative effect of plant fertilization on Lepidoptera has previously been underestimated and (2) that it contributes to the range-wide decline of Lepidoptera.

Plants were collected and prepared for chemical analysis, total phenolics, anthocyanins concentrations, and free radical scavenging activity. Results showed that, protein concentration of Malva parviflora (22.9%) was the highest among the plants. Ruta chalepensis had high levels of fat and carbohydrates (4.2% and 51.7%, respectively), but had the lowest level of ash (8.7%). Mineral concentrations varied and found to have appreciable amounts of Ca, Na, K, Cu, Fe, Mg, Mn, Zn and P. Total phenolic ranged from 163.1 (Tetragonolobus palaestinus) to 1328.8 mg GAE/100g (Ruta chalepensis). Anthocyanins ranged between 18.1 (Gundelia tournefortii) and 100.1 mg/100g (Rumex acetosella). These plants differed in free radical scavenging activity. It was concluded that these plants could be considered as natural sources for antioxidants and valuable natural resources as a new addition to the diet of inhabitants.

The present study was carried out to evaluate the response of microbial bioinoculants along with different organic manures (vermicompost and greencompost) on growth, yield and nutrient uptake of Rumex. Field experiments were carried out in 2010-2011 in randomized replicated block designs consisting of four replicates of each treatment. The experiment consisted of five different microbial bioinoculants combined with two organic manures. Various treatments given to Rumex were Frateuria aurentia (potassium mobilizer) Trichoderma viride (biocontrol agent), Azospirillium brasilense (Nitrogen source) and Pseudomonas fluorescens (plant growth promoting bacteria) significantly increased plant biomass, yield and nutrient content of Rumex. Results revealed that among the two organic manures vermi compost combined with bioinoculants significantly influenced the growth and nutrient uptake. Plants inoculated with vermicompost and Frateuria

Background and Aims Seed bank persistence plays a highly relevant role for population dynamics. The impact of interacting environmental factors on seed longevity has only scarcely been investigated. We aimed to analyse the effects of varied soil substrate type and moisture on soil seed survival.

Background There are no data on atmospheric pollen in Talca. In the present work, our aim is to describe the amount of pollen grain in the atmosphere of the city of Talca likely to cause pollinosis of its inhabitants. Methods A volumetric Hirst sampler (Burkard seven-day recording device) was used to study pollen levels. It was placed in the centre of Talca from May 2007 to April 2008. Results The highest airborne presence of pollen, as measured in weekly averages, was Platanus acerifolia with a maximum weekly daily average of 203 grains/m3 registered during September and October. The second highest was Acer pseudoplatanus with a maximum weekly daily average of 116 grains/m3. Populus spp. had a maximum weekly daily average 103 grains/m3. Olea europaea reached 19 grains/m3 in November. Grasses presented high levels of pollen counts with a maximum weekly daily average of 27 grains/m3 from the end of August until the end of January. Pollens of Plantago spp. Rumex acetosella and Chenopodium spp. had a similar distribution and were present from October to April with maximum weekly daily average of 7 grains/m3, 7 grains/m3 and 3 grains/m3 respectively. Significant concentrations of Ambrosia artemisiifolia were detected from February until April. Conclusion The population of Talca was exposed to high concentrations of allergenic pollen, such as P. acerifolia, A. pseudoplatanus, and grasses in the months of August through November. The detection of O. europaea and A. artemisiifolia is important as these are emergent pollens in the city of Talca. Aerobiological monitoring will provide the community with reliable information about the level of allergenic pollens, improving treatment and quality of life of patients with respiratory allergy.

There are two main methods for estimating seed density and species composition of soil seed banks: manual seed extraction and seedling emergence. These methods were used to determine and compare seed density and species composition in the soil of a natural grassland in Patagonia. Additionally, known amounts of seeds of different sizes from Patagonian grassland species were mixed with soil to evaluate the efficiency of the seed extraction method, and determine their recovery percentage. Seed density found in the grassland soil with the extraction method was four times higher than that found with the seedling emergence method. Through the use of these two methods, there was very little overlap found in species composition. Small seeds (< 1 mm) were only found with the seedling emergence method, whereas the seeds of species with specific germination requirements were found with the seed extraction method. Seed recovery of grassland species varied from 2.5% for smaller seeds (Erophila verna) to 100% for larger seeds (Rumex acetosella) with the seed extraction method. This method was more effective in detecting seeds of large-seeded species. Discrepancies in seed detection between both methods may be related to seed dormancy, specific germination requirements, seed size and mass. These two methods are necessary to describe seed density and seed bank composition. Fil: Gonzalez, Sofia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Ghermandi, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina

In this study we investigated the temporal variability of N-source utilization of pioneer plant species in different early successional stages of dry acidic grasslands. Current theory states that plant species occupy distinct ecological niches and that there are species-specific, temporal N-uptake patterns. We hypothesized that small-scale dynamics in the natural habitat may affect niche differentiation among plant species. We investigated N-uptake patterns of two co-occurring plant species from different functional groups (Corynephorus canescens, Rumex acetosella) under natural conditions using N-15-labeled nitrate and ammonium in three different early successional stages during early and late summer. We found (1) marked seasonal dynamics with respect to N-uptake and N-source partitioning, and (2) different uptake rates across successional stages but a similar N-form utilization of both species. Nitrate was the main N-source in the early and later successional stages, but a shift towards enhanced ammonium uptake occurred at the cryptogam stage in June. Both species increased N-uptake in the later successional stage in June, which was associated with increasing plant biomass in C. canescens, whereas R. acetosella showed no significant differences in plant biomass and root/shoot-ratio between successional stages. Ammonium uptake decreased in both species across all stages with increasing drought. Nevertheless, the peak time of N-uptake differed between the successional stages: in the early successional site, with the lowest soil N, plants were able to extend N-uptake into the drier season when uptake rates in the other successional stages had already declined markedly. Hence, we found a pronounced adjustment in the realized niches of co-occurring plant species with respect to N-uptake. Our results indicate that ecological niches can be highly dynamic and that niche sharing between plant species may occur instead of niche partitioning.

Fire affects grassland composition by selectively influencing recruitment. Some exotic species can increase their abundance as a consequence of fire-stimulated seed germination, but response may depend on seed age. Rumex acetosella L. (Polygonaceae, sheep’s sorrel) is a cosmopolitan herb that has invaded NW Patagonia’s grasslands. This species forms persistent soil seed banks and increases after disturbances, particularly fire. We studied how fire and seed longevity influence R. acetosella germination. In 2008, we conducted laboratory experiments where we exposed different-aged seeds (up to 19 years old) to heat, smoke, charcoal, ash and control treatments. Total percentage germination and mean germination time depended on both seed age and fire treatment. Germination of younger seeds decreased with increasing temperature. There was no general pattern in germination responses of different-aged seeds to smoke, charcoal and ash. While smoke improved the germination of fresh seeds, charcoal decreased germination. Germination of untreated seeds was negatively correlated with seed age, and mean germination time increased with seed age. In most treatments, fresh seeds had lower germination than 1–5-year-old seeds, indicating an after-ripening requirement. Smoke stimulates R. acetosella germination, causing successful recruitment during post-fire conditions. Fresh seeds are particularly responsive to fire factors, possibly because they have not experienced physical degradation and are more receptive to environmental stimuli. Knowing the colonisation potential from the soil seed bank of this species during post-fire conditions will allow us to predict their impact on native communities.

The antioxidative activity of the 80% ethanol extract obtained from eleven commonly consumed wild edible plants was determined according to the phosphomolybdenum method, reducing power, metal chelating, superoxide anion and free radical scavenging activity and compared to standard compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and trolox. Total phenolic compounds, flavonoids, and anthocyanins in the extracts were also measured. Trachystemon orientalis, Vaccinium mrytillus, Rumex acetosella Polygonum amphibium, Beta vulgaris, and Similax Excelsa had the highest antioxidant capacities. Overall results showed that these plants can serve as good sources of bioactive polyphenols in the human diet and can be regarded as good candidates for nutritional supplement formulations due to their high concentrations of total phenolic compounds, flavonoids and anthocyanins as well as their strong antioxidant activity.La actividad antioxidante de extractos etanólicos al 80%, obtenidos de once plantas salvajes comúnmente consumidas, fue determinada por el método del fosfomolibdeno, poder reductor, actividad quelatante de metales, actividad captadora de aniones superóxidos y actividad captadora de radicales libres, y comparada con compuestos patrones tales como el butil hidroxianisol (BHA), butil hidroxitolueno (BHT) y Trolox. El contenido de fenoles totales, flavonoides y antocianinas en el extracto fue también determinado. Trachystemon orientalis, Vaccinium mrytillus, Rumex acetosella Polygonum amphibium, Beta vulgaris, y Similax Excelsa tienen las capacidades antioxidantes más altas. En general, los resultados muestran que estas plantas pueden servir como una buena fuente de polifenoles bioactivos en la dieta humana, y pueden ser considerados como buenos candidatos para su uso como suplemento nutricional en formulaciones debido a su alta concentración en fenoles, flavonoides y antocinainas y a su fuerte actividad antioxidante.

Using a unique sterile design intended to eliminate outside seed contamination of horse feces, we investigated whether weed seeds germinate after digestion by horses. Feces were collected from selected National Parks and other locations in central and northern California. All potted fecal samples were irrigated and grown in an enclosed sterile nursery environment. Thirty-two plant spe- cies emerged from these fecal samples, 24 of which were not native to California. None of these were identified on the California Department of Agriculture's Noxious Weed List, which is used as a basis to certify equine feed as weed free. However, seven of the non-native species are identified as moderately invasive on the California Invasive Plant Council's (Cal-IPC) list. These species are: Hirschfeldia incana, Hordeum marinum, Lolium multiflorum, Mentha pulegium, Rumex acetosella, Trifolium hirtum, and Vulpia myuros. In addition, the following four non-native plants are listed at the limited invasiveness level on the Cal-IPC list: Hypochaeris glabra, Lythrum hyssopifolium, Medicago polymorpha, and Poa pratensis. Because we did not survey invasive plant cover in locations from which we sampled, we cannot guarantee that species identified in our samples would have also germinated in the field. Our results add to a growing body of literature documenting germination of seeds after passing through the digestive system of horses and suggest that conscientious horse owners should select feed sources that are free of weeds. We also find that the current list of noxious weeds used to certify weed-free feed for equines should be comprehensive.

We evaluated the combined effects of fire after drought on the seed bank composition and its role in the postfire recovery of NW Patagonia grasslands. During three years, we monitored the seed bank and the aboveground vegetation. Species were arranged in functional groups and Detrended Correspondence Analysis was used to separate sites according to species and functional groups. Similarity between aboveground vegetation and seed bank was calculated with SOrensen Index. In the first year, the seed density was similar in the control and burned sites and was lower than following years in all the sites. The species that survived the high temperatures were all annuals with the exception of the perennial species Fabiana imbricata and Rumex acetosella. In the second postfire year, the diversity and seed density increased due to the contribution of fugitive species (rare in the community) and exotic annual species. Seed bank of perennial species was the most affected by fire and just recovered in the third year. Drought did not affect the similarity between the seed bank and vegetation. Fire had low impact on the total seed bank, probably due to the heat buffering nature of the soil, whereas drought reduced significantly seed bank size and richness. Seed bank contributes to grassland richness maintenance.

We used dual labelled stable isotope (13C and 15N) techniques to examine how grassland plant species with different growth strategies vary in their ability to compete with soil microbes for different chemical forms of nitrogen (N), both inorganic and organic. We also tested whether some plant species might avoid competition by preferentially using different chemical forms of N than microbes. This was tested in a pot experiment where monocultures of five co-existing grassland species, namely the grasses Agrostis capillaris, Anthoxanthum odoratum, Nardus stricta, Deschampsia flexuosa and the herb Rumex acetosella, were grown in field soil from an acid semi-natural temperate grassland. Our data show that grassland plant species with different growth strategies are able to compete effectively with soil microbes for most N forms presented to them, including inorganic N and amino acids of varying complexity. Contrary to what has been found in strongly N limited ecosystems, we did not detect any differential uptake of N on the basis of chemical form, other than that shoot tissue of fast-growing plant species was more enriched in 15N from ammonium-nitrate and glycine, than from more complex amino acids. Shoot tissue of slow-growing species was equally enriched in 15N from all these N forms. However, all species tested, least preferred the most complex amino acid phenylalanine, which was preferentially used by soil microbes. We also found that while fast-growing plants took up more of the added N forms than slow-growing species, this variation was not related to differences in the ability of plants to compete with microbes for N forms, as hypothesised. On the contrary, we detected no difference in microbial biomass or microbial uptake of 15N between fast and slow-growing plant species, suggesting that plant traits that regulate nutrient capture, as opposed to plant species-specific interactions with soil microbes, are the main factor controlling variation in uptake of N by grassland plant species. Overall, our data provide insights into the interactions between plants and soil microbes that influence plant nitrogen use in grassland ecosystems.

To date, the implications of the predicted greater intra-annual variability and extremes in precipitation on ecosystem functioning have received little attention. This study presents results on leaf-level physiological responses of five species covering the functional groups grasses, forbs, and legumes in the understorey of a Mediterranean oak woodland, with increasing precipitation variability, without altering total annual precipitation inputs. Although extending the dry period between precipitation events from 3 to 6 weeks led to increased soil moisture deficit, overall treatment effects on photosynthetic performance were not observed in the studied species. This resilience to prolonged water stress was explained by different physiological and morphological strategies to withstand periods below the wilting point, that is, isohydric behavior in Agrostis, Rumex, and Tuberaria, leaf succulence in Rumex, and taproots in Tolpis. In addition, quick recovery upon irrigation events and species-specific adaptations of water-use efficiency with longer dry periods and larger precipitation events contributed to the observed resilience in productivity of the annual plant community. Although none of the species exhibited a change in cover with increasing precipitation variability, leaf physiology of the legume Ornithopus exhibited signs of sensitivity to moisture deficit, which may have implications for the agricultural practice of seeding legume-rich mixtures in Mediterranean grassland-type systems. This highlights the need for long-term precipitation manipulation experiments to capture possible directional changes in species composition and seed bank development, which can subsequently affect ecosystem state and functioning info:eu-repo/semantics/publishedVersion

We investigated clonal traits in the dioecious herb Rumex acetosella to characterize sexual dimorphism in clonal forms and to correlate below-ground clonal patterns and above-ground ramet distributions. We recorded creeping root length, branching patterns, ramet and clump (caespitose ramets from the same position on the root) sprouting patterns, and biomass allocations in three females and males. We also estimated the patch size of flowering ramets within a quadrat. No sexual dimorphism was detected in the frequencies of branches and flowering ramets per root length. Male plants allocated proportionally more biomass to below-ground organs. Total root length did not differ between the sexes. Females sprouted more clumps with fewer flowering ramets per root length than males, which sprouted fewer clumps with more flowering ramets, which meant that clump sprouting patterns were phalanx-like in females and guerrilla-like in males. Flowering ramets were aggregately distributed in both females and males and patch sizes were similar between sexes, indicating that the spreader propagations were not found in the guerrilla-like males. We assumed that sexual dimorphism occurred in response to physiological integration for higher reproductive effort in females.

This paper deals with the complex issue of reversing long-term improvements of fertility in soils derived from heathlands and acidic grasslands using sulfur-based amendments. The experiment was conducted on a former heathland and acid grassland in the U.K. that was heavily fertilized and limed with rock phosphate, chalk, and marl. The experimental work had three aims. First, to determine whether sulfurous soil amendments are able to lower pH to a level suitable for heathland and acidic grassland re-creation (approximately 3 pH units). Second, to determine what effect the soil amendments have on the available pool of some basic cations and some potentially toxic acidic cations that may affect the plant community. Third, to determine whether the addition of Fe to the soil system would sequester PO4− ions that might be liberated from rock phosphate by the experimental treatments. The application of S0 and Fe(II)SO4− to the soil was able to reduce pH. However, only the highest S0 treatment (2,000 kg/ha S) lowered pH sufficiently for heathland restoration purposes but effectively so. Where pH was lowered, basic cations were lost from the exchangeable pool and replaced by acidic cations. Where Fe was added to the soil, there was no evidence of PO4− sequestration from soil test data (Olsen P), but sequestration was apparent because of lower foliar P in the grass sward. The ability of the forb Rumex acetosella to apparently detoxify Al3+, prevalent in acidified soils, appeared to give it a competitive advantage over other less tolerant species. We would anticipate further changes in plant community structure through time, driven by Al3+ toxicity, leading to the competitive exclusion of less tolerant species. This, we suggest, is a key abiotic driver in the restoration of biotic (acidic plant) communities.

Green manuring of sunflower and dhaincha reduced plant population of Phalaris minor 100 per cent under lab and 42 per cent and 15 per cent, respectively, under field conditions, thus, indicating the inhibitory role of allelo-chemicals. Grain yield of wheat was significantly higher with the green manuring of sunflower and dhaincha before rice transplanting over summer fallow. The allelopathic potential of broad-leaved weeds of wheat in inhibiting germination of P. minor was in the order of Chenopodium album=Medicago denticulata=Melilotus indica=Convolvulus arvensis (100 per cent inhibition) > Vicia hirsuta (86 per cent) > Cirsium arvense (48 per cent) > Lathyrus aphaca (38 per cent) > Rumex acetosella (9 per cent). Exudates of rice cultivars HKR 126, IR 64, Jaya and Haryana Basmati-1 registered >50 per cent inhibition of germination of P. minor . As the extract was diluted, effect of non-scented cultivars considerably reduced in comparison to scented group. Out of 11 wheat varieties, WH533 provided the highest inhibition of germination (30 per cent) followed by WH542 (21 per cent).

Semiarid grasslands in NW Patagonia (Argentina) are dominated by Festuca pallescens and Pappostipa speciosa, two native tussock grasses that differ in water stress tolerance and in palatability to livestock. Both species regenerate in gap microsites invaded by the exotic herb Rumex acetosella. We performed a greenhouse experiment to study the effect of Rumex competition on early growth of the dominant tussock-grasses. In February 2008 we used about 4-month-old seedlings to establish competition treatments that simulated a dry or wet summer. Competition among grasses was also quantified to relativize the effect of Rumex competition on each grass species. Rumex seedlings had a negative impact on grass seedlings, but it was not greater than that produced by any co-dominant grass. Grass species did not differ in their sensitivity to competition by Rumex or to water stress. In dry conditions, there was an intense underground competition between grass species, but there was no evidence of underground competition from Rumex. The low competitive ability of Rumex under water stress may indicate that its invasive potential from a seedling stage would be limited by the aridity of the environment. Moreover, the high bud production of Rumex seedlings suggests an early contribution to the soil bud bank, a key eco-biologic trait of this invasive species. Therefore, the estimation of the bud bank abundance and the study of how vegetative regeneration may be interfering grass recruitment should be considered in future research. Fil: Franzese, Jorgelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina Fil: Ghermandi, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina

In acidic soils, monomeric aluminium (Al3+) can reach levels that are toxic to plants, thus preventing many species from growing there. Organic acids chelate Al and render it non-toxic. It has been shown that exudation of organic acids by Al-tolerant crops increases their tolerance to Al. We have extended this observation to wild plants by comparing the ability of ten herbs to exude organic acids in response to elevated Al levels. We hypothesized that exudation of organic acids was related to the ability of plants to grow on Al-rich soils. Two grasses were grown in rhizotrons in soils with 41 and 63 muM reactive Al. Organic acids were sampled from root tips connected to an intact plant-root system. Deschampsia flexuosa (L.) Trin. exuded more malic acid when grown in the soil with the highest Al content. Five forbs and five grasses were also exposed to three Al levels (0, 25 and 75 muM) in a hydroponic system. Rumex acetosella L, and Viscaria vulgaris Bernh. increased exudation of oxalic acid and Galium saxatile auct. non L. and Veronica officinalis L, increased exudation of citric acid in response to elevated Al. The distribution of the forbs in the field as described by soil pH was negatively related to the amount of organic acids exuded in response to Al. In contrast, none of the grasses exuded higher amounts of organic acids with increasing Al concentration in the hydroponic experiment. (C) 2001 Annals of Botany Company.

Recent findings have highlighted the possibility of increased fluoride (F) concentrations in herbage through F taken up from soil via the plant root. This paper aimed to assess the risk of F concentrations reaching phytotoxic or zootoxic concentrations in pasture plants. Five plant species commonly found in improved pastures in Australia, the sown species subterranean clover (Trifolium subterranean) and cocksfoot (Dactylis glomerata), and weeds barley grass (Hordeum leporinum), scotch thistle (Onopordum acanthium) and sorrel (Rumex acetosella) were grown in complete nutrient solutions with graded levels of added F to determine the effects of F− activity in solution on phytotoxicity and uptake of F by their roots. A model was developed using data from these solution culture experiments and data from the literature. The model assessed uptake of F by plants grown over a range of soil pH values and determined the risk of F taken up through the plant roots reaching phytotoxic concentrations, or concentrations potentially injurious to grazing animals, in the plant shoots. Modelling data suggested that the plants studied would not accumulate phytotoxic concentrations of F in shoots or concentrations of F deleterious to grazing animals through root uptake in neutral pH agricultural soils. The risks from F addition to soils in phosphatic fertilisers leading to reduction in pasture growth or animal health are therefore low. However, in highly F-polluted soil, as the soil becomes more acidic or alkaline, the risk of zootoxic concentrations of F in shoots of plants would increase.

Growth of Rumex acetosella, a root sprouting plant, was studied in a pot experiment. Each plant of R. acetosella consisted of two ramets which were interconnected by a root about 9 cm long. One of the ramets was placed in a compartment with nutrient-rich soil, the other with nutrient-poor soil. The root connection between the ramets either remained intact or was severed at the nutrient interface after planting. Growth of new roots was prevented at the nutrient interface. The presence of a connection between the ramets did not affect biomass or shoot production in either soil compartment, indicating a poor integration of the interconnected plant systems. In the nutrient-rich environment, two to four times more shoots and biomass were produced than in the low nutrient regime. A large proportion of buds initiated on roots remained dormant, forming a bud bank. When the number of shoots or buds was expressed per g of root dry weight or per m of root length, the nutrient response was no longer evident or, in a few cases, a significant effect in the opposite direction was obtained. These results show that the greater production of buds and shoots in the nutrient-rich environment reflected an allometric relationship between root biomass and the number of buds and shoots initiated on the roots.

Animal wastes from intensive farming are generally collected for field fertilisation. They may contain drugs that can become soil pollutants. The effect of such contamination on terrestrial biota has been demonstrated in laboratory tests on different plant species, using a common antimicrobial, sulphadimethoxine. In the near future, the monitoring of antimicrobial contamination in arable lands and their crops will be of importance for the protection of natural ecosystems and consumers. A possible tool for this monitoring is the use of weeds that can constitute a ‘mesh’ from which antimicrobial contamination can be detected. In laboratory tests, some direct effects of sulphadimethoxine contamination were demonstrated on normal development and growth of three cosmopolitan weed species, Amaranthus retroflexus L., Plantago major L. and Rumex acetosella L. These effects depended on the very high accumulation rates in plants (thousand μg g−1). P. major accumulated the highest amount of drug followed by A. retroflexus and R. acetosella. These data further highlight the environmental risk of sludge application on soils and the possible contamination of food nets; but also give a potential tool for the monitoring of antimicrobial soil contamination.

Rumex palustris is a flooding-resistant amphibious species from frequently flooded riversides, whereas Rumex acetosella is flooding-sensitive and grows on dry sandy soils. Upon complete submergence, both species accumulate ethylene to similar levels. After more than four days, however, the ethylene concentration in R. acetosella plants strongly rises to an extremely high level, whereas it remains much lower in R. palustris plants. This latter species responds to ethylene with enhanced leaf elongation, whereas elongation in R. acetosella is insensitive to ethylene. Elongation rates of leaves were measured continuously during the first 8 h of submergence. A comparison of the elongation rates of R. palustris, R. acetosella and silver-treated R. palustris plants demonstrated that R. palustris plants responded to ethylene within 1 h of submergence. In R. acetosella, clear symptoms of senescence and decay were observed within two weeks of submergence. In R. palustris plants, only the oldest leaf was senescent. To investigate the role of ethylene in the senescence process, the effects of silver ions on submerged plants, and the effects of prolonged exposure to an extremely high ethylene level on drained plants were studied in both Rumex species. The results demonstrated that although ethylene accelerated senescence of submerged R. acetosella plants, the process may have been caused by other factors. The slower senescence of R. palustris plants could not be explained by their lower ethylene concentration. Rather, it was caused by a much lower sensitivity of the senescence process to ethylene. Moreover, other factors may be less unfavourable in R. palustris than in R. acetosella plants under submerged conditions.

Rosettes of flooding-resistant Rumex palustris plants show a submergence-induced stimulation of elongation, which is confined to the petioles of young leaves. This response increases the probability of survival. It is induced by ethylene that accumulates in submerged tissues. Flooding-intolerant Rumex acetosella plants do not show this response. We investigated whether differences in shoot elongation between the species, between old and young leaves and between the petiole and leaf blade of a R. palustris plant result from differences in internal ethylene concentration or in sensitivity to the gas. Concentrations of free and conjugated ACC in petioles and leaf blades of R. palustris indicated that ethylene is synthesized throughout the submerged shoot, although production rates varied locally. Nevertheless, no differences in ethylene concentration were found between submerged leaves of various ages. In contrast, dose-response curves showed that only elongation of young petioles of R. palustris was sensitive to ethylene. In R. acetosella, elongation of all leaves was insensitive to ethylene. We conclude that variation in ethylene sensitivity rather than content explains the differences in submergence-induced shoot elongation between the two Rumex species and between leaves of R. palustris.

A model is presented of the regulation of ethylene biosynthesis in relation to submergence and flooding resistance. It is based on time-course measurements of ethylene production, ethylene accumulation, and concentrations of free and conjugated 1-aminocyclo-propane-1-carboxylic acid (ACC) in submerged and drained flooding-resistant Rumex palustris Sm. and flooding-sensitive Rumex acetosella L. plants. From these data, in vivo reaction rates of the final steps in the ethylene biosynthetic pathway were calculated. According to our model, submergence stimulates ACC formation and inhibits conversion of ACC to ethylene in both Rumex species, and as a result, ACC accumulates. This may explain the stimulated ACC conjugation observed in submerged plants. Although submergence inhibited ethylene production, physical entrapment increased endogenous ethylene concentrations in both flooding-resistant R. palustris and flooding-sensitive R. acetosella plants. However, R. palustris plants controlled their internal ethylene levels in the long term by a negative regulation of ACC synthase induced by ethylene. In flooding-sensitive R. acetosella plants, absence of negative regulation increased internal ethylene levels to more than 20 [mu]L L-1 after 6 d of submergence. This may accelerate the process of senescence and contribute to their low level of flooding resistance.

The role of ecological factors in the invasion of fescue tussock grassland by Hieracium species was investigated in a box experiment. Soil fertility and cutting frequency effects on interference between the introduced flat weeds Hieracium pilosella, H. praealtum, and Rumex acetosella and the native bunch grass Festuca novae‐zelandiae established on a denuded soil were examined using a model and technique involving stress and disturbance gradients. The weed species showed marked biomass and phenological responses to increased availability of mineral nutrients compared to F. novae‐zelandiae, which had reduced yield at the highest level of soil fertility. At high soil fertility, R. acetosella suppressed both Hieracium species and F. novae‐zelandiae, probably because it competed more effectively for light. Cutting frequency also influenced the pattern of interference between the species by effects on competition for light, vegetative spread, and partitioning of biomass to parts of the plants above an...

Summary Electrophoretic examination of the hexaploid Rumex acetosella L. revealed a substantial amount of genetic variation. Both the genotype frequencies and the distribution of genotypes varied greatly between populations. The North American populations of ssp. angiocarpus possessed less genetic variation than did the European populations of ssp. acetosella or angiocarpus, which may be due to the history of the species. The European populations of ssp. acetosella and angiocarpus appeared to be genetically more similar than the angiocarpus populations from different continents. It is likely that these two subspecies do hybridize when their populations are sympatric. The results do not confirm the presence of an association between morphometric and allozyme variation in R. acetosella.

In this study morphological variation and the potential for competition to affect biomass and seedling selection of the families of five populations of Rumex acetosella L. sampled along a successional old-field gradient have been investigated. Seeds from 25 families were submitted to four competitive regimes: no competition (one plant per pot), medium competition (two plants/ pot taking plants from the same population), high within-population competition (four individuals from the same population in a pot) and high between-population competition (four individuals from two different populations in a pot). Eight traits were analysed after 3 months of growth for variation among families within populations. A significant difference among families within the two older populations was recorded for sexual biomass and related components. High sensitivity of these traits to density was observed in all populations except the youngest, suggesting specialization to particular environmental conditions in late successional populations, and a good adaptive capacity to buffer environmental variation in the pioneer population. Little significant interaction between competitive regimes and families within populations was found, i.e. genotypes within each population showed little variation in their response to environmental variation. Genotypic variance decreased with increasing competitive conditions for the majority of the traits. However, the percentage of variance in sexual reproduction explained by family was stable among treatments. Tradeoffs between vegetative reproduction and sexual reproduction were recorded at the population level along the successional gradient, with increasing competitive conditions. As succession proceeds, we observed a decrease in sexual reproduction and an increase in vegetative reproduction. At the family level, correlation among traits were similar when plants were grown in the absence of competition and at high density, with a significant negative correlation between sexual reproduction and vegetative reproduction. For both sprout number and sexual biomass, the performance of families grown under all the treatments was positively correlated. Together these results indicate allocational constraints on the reproductive biology of R. acetosella that may be favoured by natural selection and have influenced population differentiation along the successional gradient. However, they also revealed that the potential exists for evolutionary specialization through plasticity, in response to variation in environmental conditions.

Patterns in flowering and biomass allocation in seedlings of Rumex acetosella L. collected from five successional old fields, from 1 year old to 15 years old, have been examined in experimental pots varying in density (1, 2, and 4 plants/pot) and neighbor relatedness (sib, nonsib, other population) to determine the effects of successional habitat variation on patterns of resource allocation. The flowering of seedlings from the successionally young populations was not affected by density, whereas for seedlings from the older populations, increased density was correlated with increased variation in flower and seed production both within and between populations. At high density, seedlings from the successionally youngest population showed the greatest allocation of resources to flowering. As a result, differentiation along the successional gradient was such that the younger populations invested a greater proportion of resources to aerial biomass, while the older populations allocated relatively more resources to vegetative propagation. These trends were maintained at high density. The results of the sibling competition treatment showed no consistent trend related to the age of the populations but were density dependent. At high density, sexual biomass was higher between nonsibs than between sibs of the same population, suggesting greater competition among related plants. Finally, the sexual biomass of individual plants was less in competition with seedlings from a different population than with seedlings from the same population. Sprout biomass showed the reverse trend. The observed differentiation between successionally different populations in resource allocation irrespective of density may account for these results. Overall, our results provide evidence for biotic specialization of R. acetosella in relation to successional habitat change. Key words: density, sibling competition, succession, trade-off, Rumex acetosella, resource allocation.

Vegetative growth patterns ofRumex acetosella L. were investigated both in experimental conditions and in the field. Plants originating from geographically and ecologically contrasting areas expressed significant differentiation in height, weight, and leaf production, even at early stages. The plants belonging to subsp.angiocarpus grew thaller than other plants. The differences among populations grown in a uniform environment provide evidence for genetic differentiation in morphology. Plants in natural populations were considerably lighter than experimental plants, which intensively produced a large number of rosette leaves. These differences can be attributed to substantial phenotypic plasticity. When the correlation structure among the growth traits was analyzed, seed weight and early plant size appeared to influence future plant size.

SUMMARY The effects of water stress and rewatering on the water relations and biomass of male and female plants of the dioecious herb, Rumex acetosella L., have been examined. Plants were collected from two fields, 2 and 15 yr old respectively, and submitted to different water regimes. Male plants from both populations showed a similar response to water deficit, having a low transpiration rate and low consumption of soil water, whilst maintaining a high green leaf area. Females from the two populations differed from each other more than males, both in terms of their response to drought and survival capacity. Females from the young population, which had a small greenleaf area and a small root biomass, had progressively lower water potentials and maintained higher levels of transpiration at the onset of the first drought period, indicating a progressive acclimation to water stress. They also recovered more rapidly and to a greater extent than all the others upon rewatering. Females from the old population, with a high root/shoot ratio, transpired the most prior to the onset of water stress. They maintained a high water potential throughout the stress period, having high stomatal resistances and removing more water as soil moisture declined. This is indicative of drought avoidance. Root development was, however, limited in the shallow pots, hence the water resource was depleted rapidly and mortality occurred to a greater extent in these oldfield females. These characteristics may be adaptative, given the selection pressures which operate on water balance characters along a successional gradient and the spatial segregation of sexes that has been previously observed in this dioecious species in the same old-field succession, with the sex ratio becoming progressively malebiased with time.

The effects of seed size on growth, biomass allocation and competitive ability of Rumex acetosella plants grown either individually or in competition were studied in two populations (6 months and 15 years old respectively) sampled from a postcultivation successional gradient. For plants grown individually there were highly significant effects of seed weight on growth after 43 days, with a higher relative growth rate (RGR) observed for plants raised from heavier seeds. However at the end of the experiment, seedlings developed from lighter seeds had a RGR 2 times greater than those from heavier seeds. Final biomass of the two types was not significantly different after 73 days of growth. When plants were grown individually, there were only slight differences between populations, but when grown in monocultures of 4 plants per pot, plants from the old population had higher root and leaf biomass per pot whereas those from the young population had a higher reproductive effort per pot. This suggests that a trade-off between allocation to sexual and vegetative reproduction occurs over successional time. In mixtures of light and heavy seeds, plants from light seeds were shorter, had fewer leaves and lower biomass than plants from heavy seeds, which were also taller and produced more dry matter than plants grown from heavy seeds in monoculture. The significant effects of seed weight and population on biomass parameters persisted unit the end of the experiment. Seedlings from heavy seeds were strong competitors: those from the young population grew better in the presence of neighbors than in monoculture and those from the late successional population suppressed the more the growth of their partners. Seedlings from light seeds were subordinate competitors. These results suggest that seedlings from seeds of different sizes benefit from contrasting ecological conditions and that selection acts on reproductive output along successional gradients.

Two sets of plants of Rumex acetosella L. of known sex (males and females in the same proportions), belonging to populations from two fields that were abandoned 2 and 15 years ago, were grown on soil regularly watered to field capacity or to half of field capacity. Four harvests of six plants for each sex, population and treatment were performed to follow the changes in biomass allocation to aerial and subterranean organs as related to plant water potential. In well-watered plants, the old population had a higher rate of water use than the young one because of rapid leaf surface area development and a higher root/shoot biomass ratio, which should make it more competitive in situations of strong interspecific competition, such as the late stages of succession. When plants were subjected to water stress (half of field capacity), clear-cut differences appeared between males and females at the vegetative stage. Female plants showed a good regulation of water balance and reached higher biomass values than male plants. However, flowering and fruiting induced a decrease in the root/shoot biomass ratio and in the transpiration rate of female plants, which would tend to exclude them with time. These results may explain the fact the the oldest Rumex acetosella communities consist predominantly of males.

The effects of time since abandonment and date of flowering on the number and biomass of seeds of Rumex acetosella were studied at monthly intervals over a single growing season in a successional series of abandoned fields at two sites near Paris, France. Overall, a decrease in filled-seed production per plant was observed with increasing successional age, but only for the early summer period. A similar trend was observed for reproductive effort, i.e. filled-seed production per unit of vegetative biomass (...)

SUMMARY (1) This paper examines seed input, germination and early growth of species found during the succession from heather moorland to mature birch woodland. (2) Numbers of seeds of Calluna vulgaris in the seed rain decreased rapidly with increasing age of birch stands. Large numbers of Calluna seeds were found, however, in soil beneath all ages of birch as well as the open moor, illustrating the longevity of seeds of this species. (3) Large numbers of Deschampsia flexuosa seeds arrived in the seed rain but very few germinated from the soil, indicating dependence on immediate seed regeneration, unlike Agrostis capillaris which had large, persistent soil seed stores. (4) The presence of seeds of Anthoxanthum odoratum, Agrostis capillaris and Rumex acetosella in seed rain and soil seed stores showed that the absence of these species from open moorland and young birch was not due to unavailability of propagules. (5) Germination of the species studied was apparently not affected by stand age, with the exception of Agrostis capillaris and Cerastium holosteoides which showed reduced germination on the open moor. Early growth of most species was faster, however, beneath the birch than on the open moor and improved beneath increasing ages of birch. (6) The natural regrowth of vegetation in the cleared plots was faster beneath the older birch than the young birch or the open moor. (7) The implications of differences in seed availability, germination and early growth are discussed in relation to observations and experiments on species changes beneath developing birch reported in the first two papers of this series.

Germination of Rumex acetosella L. was studied under a variety of experimental conditions to determine whether populations from old fields of different ages (fallow for 6 months to 15 years) differed in seed weight and germination rate and in plant biomass and flowering rate of the resulting plants. Fresh seeds collected from these natural populations showed differences in germination that varied with the date of harvest and the number of years since the field was last cultivated: seeds of the youngest population harvested in July germinated the best and were lighter than those of the other populations. Different fertilizer levels applied during the growth of the mother plants from seeds collected in the original old fields affected the mean weight and the germination rate of the resulting seeds, regardless of the density of cultivation of the mother plant. However, the effect of different fertilizer levels on mean seed weight varied with the origin of each population. Heavy seeds (mean weight > 0.6 mg) of mother plants from the populations of fields abandoned over 2 years ago germinated better than light seeds (mean weight

Callus cultures were established from dioecious plant species Rumex acetosella and R. acetosa, using cotyledons, hypocotyls and stem tips of aseptically germinated seedlings as primary explants. Cultures were also established from male and female R. acetosella adult plants, starting from vegetative lateral buds. Cell division was induced using a high 2,4-D concentration, while bud induction and multiplication were stimulated on a medium with high BAP/IAA ratio. Cotyledon fragments of both species produced only rhizogenic calli. Hypocotyl-derived calli of R. acetosella produced buds, while those of R. acetosa showed no bud forming response under these conditions. Bud multiplication occurred in stem tip cultures of both species and in lateral bud cultures of R. acetosella. Calli derived from male plants produced more buds than those from female. Shoots were easily rooted using IBA, and plantlets were effectively transferred to soil. Flowering was not induced in culture. The sex of regenerated male and female plants was not altered by the culture conditions.

Summary Measurements were made of the yield and habit of two lowland populations and one mid-altitude population of R. acetosella grown in soil in tins at sites near sea level, 1,900 ft, and 4,200 ft in Canterbury. Soil from each site was transported between sites in an attempt to separate climatic and edaphic effects on yield and habit. Correlations between plant height and yield were calculated. Altitudinal change of climate was the major determinant of yield and habit. Soil responses indicated the tolerance of the species to acid, base-deficient soils. The greater yield of the two lowland populations relative to the mid-altitude population diminished markedly with increasing altitude. Evidence is presented of soil adaptation to the site of origin and of plant population adaptation to soil. It is concluded that the successful colonisation of tussock grasslands by R. acetosella can be partly related to its phenotypic plasticity associated with the natural selection of habits facilitating survival in this...

Severe attacks by Ditylenchus destructor on potatoes in the south of Sweden appeared to have arisen from cultivation in infested soil. The principle risk of using slightly infected seed tubers, which in a field experiment gave a far less damaged crop than more severely injured ones, seems to be the possibility of spreading the nematode to new locations. For the occurrence of soil infestation, in some places very heavy, weed hosts were of major importance. Important weed hosts were Mentha arvensis, Stachys palustris, Potentilla anserina and Rumex acetosella, of which the last two have not before been reported as hosts. Underground decaying remains of potato plants infected by D. destructor may in autumn contain nematodes of some stage or stages which over-winter without the necessity for living plant tissue. Nevertheless, damage in potatoes seemed to become slighter after continuous cultivation of this crop.

Summary Records of time of flowering obtained from herbarium specimens of Rumex acetosella L. indicated seasonal delays and a shorter period of flowering with increasing latitude and altitude, while earlier flowering was indicated in regions of Mediterranean climate. Observations on the time of flowering in a uniform environment of populations spanning 50° of latitude showed correlations with latitude, and deviations from this trend could be attributed to adaptation to montane, continental, or Mediterranean climates. Experiments showed that the species required long days for floral induction in the seedling year, the populations varying in the length of day required, with populations from high latitudes not flowering in the prevailing daylengths at Christchurch (43° 30′S). In the second year of growth all populations flowered in the prevailing daylength at Christchurch, although long days and high temperatures hastened the maturation of flowers and the populations varied in time of flowering. Population d...

Summary Angiocarpic seeds occur in diploid, tetraploid and hexaploid populations of Rumex acetosella s.l.- gymnocarpic seeds occur in tetraploids and hexaploids only, and among the hexaploids in populations from northern and central Europe. Cell and organ sizes do not rigorously correspond with the various levels of ploidy, and the overlap in range and frequency results in monomodal distributions. All New Zealand populations are hexaploid and angiocarpic and are unlikely to have been introduced from northern and central Europe.

Particle concentrations derived from operation of a rotobar sampler at a midwestern location during 1965 to 1968 have confirmed the regular and substantial occurrence of Rumex pollen; field studies have implicated Rumex acetosella (sheep sorrel) as the primary source. Comparisons of rotobar and gravity slide data suggest that purely aerodynamic factors may decrease the recovery of Rumex pollen by the Durham sampler by as much as 50 per cent relative to grass pollen. A high frequency of positive skin reactivity to Rumex pollen extract was noted among 367 persons demonstrating some wheal and flare reactions on skin testing with extracts of common inhalant allergens. More than half of a group of positive skin reactors to Rumex extract also demonstrated positive nasal provocative tests with this material. Most, but not all, positive nasal reactors to Rumex had experienced pollinosis during the common period of Rumex and grass pollen prevalence, and at least some of these manifested negative responses on mucosal testing with grass pollen extracts. The combined aerobiological and clinical data suggest that specific sensitivity to Rumex pollen may contribute significantly to the severity of pollinosis in selected patients.

Male and female plants of Rumex acetosella were grown on a moisture gradient to measure possible differences in the drought tolerance of the sexes. The growth of both sexes declined under water stress but males were significantly more drought tolerant. This could not be explained by greater water use efficiency in the male plants; measured rates of both photosynthesis and leaf conductance did not differ significantly between the sexes. Multiple discriminant analysis showed that the sexes differed at all moisture regimes in their overall patterns of biomass allocation. Males had proportionately greater investment in root and leaf tissue which could explain their growth advantage over females under water stress. Despite essentially equal water use efficiencies, on a per plant basis males, with more leaf and root biomass, could fix more carbon and more rapidly exploit the local water resource than females. Thus the pattern of biomass allocation rather than intrinsic physiological differences appears to explain the greater drought tolerance of male plants of Rumex acetosella.

Patterns of resource allocation in the dioecious Rumex acetosa and R. acetosella were investigated. Males were found to allocate more to reproduction during flower production than females, whereas females invested considerably more in reproduction during seed production. Altogether, females allocated both a higher total amount and a higher proportion of energy to reproduction than did males. By regression analysis, the influence of plant size on reproductive effort was examined separately for males and females. The results indicated that while reproductive effort is sometimes lower for tall plants than for small plants, size-independent effects have a greater influence on reproductive effort than size distribution. An analysis of variance was conducted to investigate the effects of population, season, sex and their interactions on plant size, and an analysis of covariance was used to study differences in resource allocation patterns. Different interaction effects were found to be most important in the two species of Rumex.

While the author (Gaertner 1962) has previously reported on the freezing, preservation and preparation of native wild plants of Ontario for culinary purposes, this communication concerns itself primarily with three common weeds: sow thistle (Sonchus spp.), evening primrose (Oenothera biennis L.) and sheep sorrel (Rumex acetosella L.), which might add to our winter diet. Two of the three plants are European introductions, usually considered extremely troublesome when present in the field; the third is a native biennial. In addition, the use of the unopened male cones of pine (Pinus spp.) and spruce (Picea spp.) are described.

An experiment was conducted to determine if leaves of Rumex acetosella changed size or shape when under drought stress, and if leaves of plants taken from a xeric environment responded differently to drought stress than leaves of plants from a mesic environment. Mean leaf areas were significantly larger in plants from xeric populations in both dry and control treatments. The five largest leaves of each control individual were significantly larger on xeric plants and on those plants whose clone had survived the low moisture stress. Multivariate analyses indicated no leaf shape differences between moisture treatments or between habitat of origin. The results suggest a physiological rather than a morphological basis for drought tolerance in R. acetosella.

(1) Nitrogen fixation rates associated with various plant species growing on china clay waste materials were estimated using the acetylene reduction technique. (2) Rates associated with leguminous species (Lupinus arboreus, Ulex europaeus, Trifolium repens) were at least ten times greater than those of non-leguminous species. (3) Of the swards comprising non-leguminous species, only those with Rumex acetosella or Festuca rubra and Agrostis tennis fixed significant amounts of nitrogen, presumably in their rhizospheres. Low rates were detected in some other species. The estimated rate of atmospheric input of combined nitrogen was greater than the input from any of the non-leguminous species. (4) There was no detectable fixation by free-living micro-organisms, except with an added carbon source. (5) All rates were low, probably because of an exceptionally dry summer. (6) Legumes are therefore recommended as the most valuable method of promoting nitrogen accumulation. Nevertheless up to 50 Kg N ha-' could be applied as fertilizer to Trifolium repens without affecting its fixation rate.